Submarine geology and geophysics

OLR (1990) 37 (7)

within the company structure often plays a majorrole in the success of the project. Some operatorslocate their corrosion departments in the offshore/onshore operations and others in the designgroup. This location often has a bearing on the

60S

financial and operational approach to the project. Asuccessful CP survey is both achievable and exciting,with experienced preplanning and selection of thecorrect equipment. Oceans Tech., Inc. 3836 SpencerSt., Harvey, LA 70058, USA.

D. SUBMARINE GEOLOGY AND GEOPHYSICS

DIO. Apparatus and methods

90:3892Aitchison, John (comment) and D.P . Watson

(reply), 1990. (Discussion ol] 'Measures of variability for geological data,' by D.F. Watson andG.M. Philip. Mathl Geol., 22(2):223-231.

90:3893Bardossy, A., 1. Bogardi and W.E. Kelly , 1990.

Kriging with imprecise (fuzzy) variograms. I.Theory. Mathl Geol., 22(1):63-79. Inst. forHydro!. and Water Resour. , Univ. of Karlsruhe,Kaiserstr. 12, D-7500 Karlsruhe, FRO.

90:3894Bardossy, A., I. Bogardi and W.E. Kelly, 1990.

Kriging with Imprecise (fuzzy) variograms. n.Application. Mathl Geol; 22(1):81-94. Inst. forHyro!. and Water Resour., Univ. of Karlsruhe,Kaiserstr. 12, D-7500, Karlsruhe, FRO.

90:3895Bosence, Dan and Dave Waltham, 1990. Computer

modeling the internal architecture of carbonateplatfonns. Geology, geol. Soc. Am., 18(1):26-30.

A numerical computer model is presented whichgenerates cross-sections of surfaces developed on acarbonate platform at -IOO-yr intervals undervarying values of carbonate production, subaerialand submarine erosion, sediment redeposition, andsea-level changes; results are displayed in 10 kaincrements . The program produces prograding anddown lapping platform geometries in associationwith stillstand and transgressive sea levels, lagoondevelopment with transgressive sea levels, anddownlapping clinoforms and erosional upper surfaces with regressive sea levels. Dept, of Geol ., RoyalHolloway and Bedford New Coli., Univ. of London ,Egham, Surrey TW20 OEX, UK. (hbf)

90:3896Cedhagen, Tomas, 1989. A method for disaggregating

clay concretions and eliminating formalin smell inthe processing of sediment samples. Sarsia,74(3):22]-222 . Dept. of Zoo1., Univ. of Goteborg, P.O. Box 25059, 8-400 31 Ooteborg,Sweden.

90:3897Cox, N.J., 1990. A note on John Playfair and the

statistics of directional data. Mathl Geol; 22(2):211-212.

It was John Playfair who, in 1802, first recognizedthat the average of any set of bearings was meaningless if it was taken to be their arithmetic mean.(The arithmetic mean of headings of I D and 359°,each just shy of due north, is 180°, due south.)Instead, it must be the arctangent of the ratio of thesum of the sines and the sum of the cosines of thebearings. (Playfair's brother Will iam invented thebar chart, the pie chart and the circle graph.) Dept.of Geogr., Univ. of Durham, DHI 3LE, UK. (fcs)

90:3898Dunstan, S.P. and A.J.B. Mill, 1989. Spatial indexing

of geological models using linear ectrees. Computers, Geosciences, 15(8);1291-1301.

Recent developments in the field of solid modeling,most notably that of octree encoding, offer greatpotential for computer-aided design applications ingeological modeling. The ability of the octreeencoding technique to index spatially attributabledata as blocks of variable levels of resolutionenhances the manipulative properties of a geologicaldatabase and reduces computational overheads. Inaddition , variable-sized blocks are better suited tothe representation of complex geological structuresand boundary features. This paper outlines thefundamentals of oetree encoding and presents two

606 D. Submarine Geology and Geophysics OLR (1990)37 (7)

algorithms for the compression and performance ofBoolean operations on linear octrees. C.A.D. Res.Group, Dept. of Mineral Resour. Engng, ImperialCollege, London SW7 2BP, UK.

90:3899Friedl, M.A., K.C. McGwire and J.L. Star, 1989.

MAPWD: an interactive mapping tool for accessing goo-referenced data sets. Computers, Geosciences, 15(8):1203-1219.

MAPWD is a graphical tool which allows the user topoint to areas of interest using an electronic map,instead of manually entering coordinate values. Theuser is able to identify regions of interest using mapswith comparable detail at a wide range of spatialscales. Remote Sensing Res. Unit, Univ. of California, Santa Barbara, CA 93106, USA.

90:3900Hunter, J.A. and S.E. Pullan, 1990. A vertical array

method for shallow seismic refraction surveying ofthe sea floor. Geophysics, 55(1):92-96. Geo!.Survey of Canada, 601 Booth St., Ottawa, ONKIA OE8, Canada.

90:3901Larsen, J.c., 1989. [Magnetotelluric) Transfer func

tions: smooth robust estimates by least-squaresand remote reference methods. Geophys. J. int;99(3):645-663. PMEL, NOAA, 7600 Sand PointWay NE, Seattle WA 98115-0070, USA.

90:3902Malinverno, Alberto, M.H. Edwards and W.B.F.

Ryan, 1990. Processing of SeaMARC swathsonar data. IEEE JI ocean. Engng, 15(1):14-23.

This paper describes the acquisition and processingof data collected by the SeaMARC swath mappingsonars. The system has two basic configurations:deep-towed, which acquires' high-resolution backscatter imagery at slow survey speeds, and shallowtowed, which simultaneously acquires lower resolution backscatter and bathymetric information athigher speeds. Processing techniques applied to thedata include: compaction of the original data bydecimation, radiometric corrections, derivation andmerging of vehicle navigation with the sonar data,integration of backscatter and bathymetric information, and geometric corrections for plotting datain geographic coordinates. Lamont-Doherty Geol.Observ. of Columbia Univ., Palisades, NY 10964,USA.

90:3903Mitterer, R.M. and Nivat Kriausakul, 1989. Cal

culation of amino acid racemization ages based on

apparent parabolic kinetics. Quat. Sci. Revs,8(4):353-357.

Instead of applying reversible first-order kinetics, theracemization and epimerization reactions can bemodeled in terms of apparent parabolic kinetics, aprocedure that generates a linear relationship between square root of age of samples and D/L values.Data from a variety of specimens show that therelationship between square root of age and D/Lamino acid is linear to a D/L value of about 1.0.This approach provides a simple expression forcalculating ages of fossils over a greater portion ofthe racemization and epimerization reaction range.Dept. of Geosci., Univ. of Texas, P.O. Box 830688,Richardson, TX 75083-0688, USA.

90:3904Ozdemir, Huseyin and Ruhi Saatcilar, 1990. Tuto

rial. Efficient multichannel filtering of seismicdata. Geophys. Prospect; 38(1): 1-22. Schlumberger Middle East SA., P.O. Box 21, AbuDhabi, United Arab Emirates.

90:3905Randall, G.E., 1989. Efficient calculation of differ

ential seismograms for lithospheric receiver functions. Geophys, J. int; 99(3):469-48 I. Seismol.Lab., MacKay School of Mines, Univ. ofNevada, Reno, NV 89557, USA.

90:3906Sheng, Ping, Benjamin White and Balan Nair, 1989.

Lithological correlations and seismic wave localisation in the Earth's subsurface. Inverse Problems, 5(6):L57-L63.

An examination of sonic well log data from a varietyof geophysical environments reveals that the elasticproperty of strata exhibits a 'well-defined exponential correlation with correlation length of the orderof 2-15 m.' Numerical simulation experimentsindicate good agreement with localization theorypredictions on both frequency dependence of localization length (15-30 km at 20 Hz and 1.5-5 km at100Hz) and the character of the backscatteredspectrum. Exxon Res. and Engng. Co., Rte. 22 East,Clinton Township, Annandale, NJ 08801, USA.(hbf)

90:3907Strobel, John et aI., 1989. Interactive (SEDPAK)

simulation of clastic and carbonate sediments inshelf to basin settings. Computers, Geosciences,15(8):1279·1290.

SEDPAK is an interactive computer simulationwhich erects models of sedimentary geometries by

OLR (1990) 37 (7) D. Submarine Geology and Geophysics 607

infilling a basin from both sides with a combinationof clastic sediment or in-situ and transportedcarbonate sediments. The modeled geometries ofclastic and carbonate sediments evolve through timeand respond to depositional processes that includetectonic movement, eustasy, and sedimentation.Clastic modeling includes sedimentary bypass, erosion, and sedimentation; carbonate modeling includes progradation, hard grounds, downslopeaprons, keep up, catch up, back step and drownedreef facies as well as lagoonal and epeiric facies. Alsoincluded in the model are extensional verticalfaulting of the basin, sediment compaction, andisostatic response to sediment loading. Dept. ofGeo\. Sci., Univ. of South Carolina, Columbia, SC29268, USA.

90:3908Walden, A.T., 1990. Improved low-frequency decay

estimation using the rnultipaper spectral analysismethod. Geophys. Prospect; 38(1):61-86. BPExploration Co. Ltd, Geophys. R&T Serv.,Britannic House, Moor Ln., London EC2Y9BU, UK.

90:3909Wapenaar, C.PA and a.c. Haime, 1990. Elastic

extrapolation of primary seismic P- and S- waves.Geophys. Prospect; 38(1):23-60. Lab. of Seis. andAcoust., Delft Univ. of Tech., P.O. Box 5046,2600 GA Delft, Netherlands.

90:3910Ware, Colin, 1989. Fast hill shading with cast

shadows. Computers, Geosciences, 15(8):13271334. School of Computer Sci., Univ. of NewBrunswick, Box 4400, Fredericton, NB E3BSA3, Canada.

90:3911Williams, J.J., P.D. Thorne and A.D. Heathershaw,

1989. Comparisons between acoustic measurements and predictions of the bedload transport ofmarine gravels. Sedimentology, 36(6):973-979.Proudman Oceanogr. Lab., Bidston Observ.,Merseyside L43 7RA, UK.

D40. Area studies, surveys, bathymetry

90:3912Collot, J.-Y. et al., 1989. First results of dives during

the SUBPSO I cruise in the collision zonebetween tbe d'Entrecasteaux ridges and the NewHebrides Island Arc. C. r. Acad. Sci; Paris, (Ser,II)309(19):1947-1954. (In French, English summary.)

Geological cross-sections constructed from observations and samples collected by submersible revealthat the inner wall of the New Hebrides Trench infront of the North d'Entrecasteaux Ridge andBougainville guyot is composed of volcanic andvolcaniclastic rocks, most likely shed from the arc.The bedding of the arc-slope rocks, which slopetrenchward in the collision zone, dips steeplyarcward near the contact between colliding features.With the exception of the rocks on the ridge east ofthe Bougainville guyot, the arc-slope rocks arehighly fractured, sheared, deeply incised by channels, and show numerous fresh slump scars. Noevidence for fluid venting was observed. ORSTOM,B.P. AS, Noumea, New Caledonia.

90:3913Monzier, Michel et al., 1989. First results of

SUBPSO I dives in the collision zone 'lAyaltyIslands Ridge/New Hebrides Island Arc' (southwest Pacific). C. r. Acad. Sci; Paris, (Ser.II)309(20):2069-2076. (In French, English summary.)

Four dives were conducted over the collision zone ofthe Loyalty Ridge/New Hebrides Arc. Basaltic andrhyolitic breccias overlain by reef limestones wereobserved on the Loyalty Ridge. An andesitic volcaniclastic sequence outcrops on the west flank ofthe New Hebrides Arc. Near the trench, the LoyaltyRidge has been cut by normal faults along whichreef limestones have collapsed for at least 4000 m.The observations confirm the unusual presence ofSW verging anticlines on the outer wall, 1000 mabove the trench; these folds affect rocks on thelower ridge flank. ORSTOM, B.P. A5, NoumeaCedex, New Caledonia.

D50. Subsurface structure

90:3914Henry, W.J. et al., 1990.A seismic investigation of the

Kenya Rift Valley. Geophys. J. int; 100(1):107130.

The Kenya Rift International Seismic Project(KRISP85), which consisted of two seismic linesalong and across the southern rift, provided profilesthat suggest a 1.5 to 6 km of rift infill resting on aPrecambrian metamorphic basement. A localizedhigh-velocity body east of Nakuru may indicate thepresence of a basic intrusive. Changes in P-wavevelocity at -12.5 km below sea level are inferred torepresent the brittle-ductile transition zone. A highP-wave velocity layer at -22 km below sea levelmay be the top of a sill-like intrusive, and a still

608 D. Submarine Geology and Geophysics OLR (1990) 37 (7)

higher velocity at ~34.0 km is identified as uppermantle material. The data imply only moderatecrustal thinning beneath this section of the rift. EssoExpro UK Ltd., Biwater House, Portsmouth Rd.,Esther, Surrey, UK. (hbf)

D60. Geomorphology (fans, canyons, etc.)

90:3915Prior, D.B. and B.D. Bornhold, 1989. Submarine

sedimentation on a developing Holocene fan delta[British Columbia). Sedimentology, 36(6);10531076.

The submarine morphology, sediments and 3-Dgeometry of a developing fan delta in a fjord (waterdepth 410 m) supplied with coarse-grained sedimentsfrom a fjord-side river are described. Fan construction began about 10-12,000 yrBP and is ongoing.Initially, acoustically chaotic sediment wedges wereemplaced over fjord-bottom glaciomarine deposits.Subsequent aggradation/progradation resulted inmoderately dipping sequences interrupted by localchaotic units. The present fan surface is divided intosix zones arranged concentrically from the fan apex,on the basis of form, sediment and process interpretations. Continued growth results from settling ofriver-derived sediments from suspension and downslope sediment dispersal by episodic gravity flows,apparently fed by underflows from the river. Geol.Survey of Canada, Atlantic Geosci. Ctr., Dartmouth,NS B2Y 4A2, Canada.

90:3916Weimer, Paul, 1989. Sequence stratigraphy of the

MississippiFan (Plio-Pleistocene), GuH of Mexico. Geo-Marine Letts, 9(4):185-272.

Analysis of 19,000 km of multifo1d seismic datacollected along a regularly spaced, dense grid defines17 seismic sequences within the Plio-Pleistocenesediments of the Mississippi Fan in the northernGulf of Mexico. The data set allows a modernsubmarine fan to be studied in far greater detail thanhas been possible previously and illustrates a widevariation of distribution of facies and sedimentswithin different parts of the fan. Mobil Res. andDevelop., 13777 Midway Rd., Dallas, TX 75244,USA.

D70. Coasts, beaches, marshes

90:3917Ball, M.M. (comment), H.T. Mullins and A.C. Hine

(reply), 1990. IDiscussion of) 'Scalloped bank

margins: beginning of the end for carbonateplatforms?' Geology, geol. Soc. Am., 18(1):95-96.

90:3918Brush, G.S., 1989. Rates and patterns of estuarine

sediment accumulation. Limnol. Oceanogr;34(7):1235-1246.

Estuarine sedimentation rates are estimated forvertical increments of sediment cores by adjustingaverage rates between dated horizons with the ratioof pollen concentration to concentration of sediment. Comparisons of detailed, pollen-derived sedimentation rates with historical records of climaticand anthropogenic events in upper Chesapeake Bayshow that highest rates of sediment accumulationoccur in upper and middle stretches of tidaltributaries and coincide with major storms andperiods of intensive land clearance when >20% oftotal land area in a given watershed is deforested andunder cultivation. Dept. of Geogr. and Environ.Engng, The Johns Hopkins Univ., Baltimore, MD21218, USA.

90:3919Chauhan, O.S. and A.K. Chaubey, 1989. Compar

ative studies of moment, graphic and phi measureson the sands of the east coast beaches, India.Sedim. Geoi; 65(1-2);183-189. Natl. Inst. ofOceanogr., Dona Paula, Goa 403 004, India.

90:3920Davis, R.A. Jr., Margaret Andronaco and J.C.

Gibeaut, 1989. Formation and development of atidal inlet from a washover fan, west-centralFlorida coast, USA. Sedim. Geol; 65(1-2):87-94.Dept. of Geol., Univ, of South Florida, Tampa,FL 33620, USA.

90:3921Galli, Gianni, 1989. Is Holocene storm-generated

stratification in Florida Bay a reflection of solarstorm cycles? Palaeogeogr. Palaeoclimatol.Palaeoecol; 76(1-2):169-185.

A descriptive analysis of surficial sediments of CraneKey showed that the sediments consist of stormlayers and algal laminated sediments. Storm layersare riddled with gas escape vugs, dissolution vugs,burrows, rootholes and cryptalga1 vugs, Periodograms of sea-level variations match the frequencydistribution of strong intensity storms which occurred in south Florida since the beginning of thiscentury. The calculated recurrence time of strongstorms (l0±3 yr) and the time interval of formationof the sequence (lOO±25 yr) are probably a responseof climatic parameters to short-period (ll-yr) andlonger-period (90-110 yr) cycles of solar activity.


Comparison with the ancient record shows analogous sequences probably linked to solar cycles and1(}2 yr sea-level rises. Via Samacchini 5, 40141Bologna, Italy.

90:3922Harris, PT., 1989. Sandwave movement under tidal

and wind-driven currents in a shallow marineenvironment: Adolphus Channel, northeasternAustralia. Continent . Shelf Res; 9(11):98I-1002.

The sandwaves average 3.9 m in height , 102 m inwavelength and are composed of up to 96% carbonate, consisting primarily of intact and fragmented calcareous alga Halimeda, benthic foraminifers, bryozoans and molluscs. Current speeds measured I m above the bed averaged 0.42 m- I andreached a peak of 1.36 m- I • Surveys carried out inSeptember and February show that the sandwavesreversed their asymmetric orientation over this timeinterval, attributed to a change in the direction of thewind-driven currents during the monsoon. Thereversal of asymmetry was accompanied by astatistically significant change in the degree ofsandwave asymmetry whereas no change in meanwavelength was detected. Ocean Sci. Inst. , Univ. ofSydney, NSW 2006, Australia.

90:3923Hickin, RJ., 1989. Contemporary Squamish River

sediment nux to Howe Sound, British Columbia.Can. J. Earth Sci., 26(10):1953-1963. Dept. ofGeogr., Simon Fraser Univ., Burnaby, BC V5A186, Canada.

90:3924Smith, N.D., A.C. Phillips and R.D. Powell, 1990.

Tidal drawdown: a mechanism for producingcyclic sediment laminations in glaciomarinedeltas. Geology, geol. Soc. Am., 18(1):10-13.Dept. of Geo!. Sci., Univ. of Illinois, Box 4348,Chicago, IL 60680, USA.

90:3925Stearley, R.F. and A.A. Ekdale, 1989. Modern

marine bioerosion by macroinvertebrates, northern GnU of California. Palaios; 4(5) :453-467.Dept. of Geol. and Mus. of Paleontol., Univ. ofMichigan, Ann Arbor, MI 49109, USA.

90:3926Williams, H.F.L. and M.e. Roberts, 1989. Holocene

sea-level change and delta growth: Fraser Riverdelta, British Columbia. Can. J. Earth Sci.,26(9):1657-1666. Dept. of Geogr. and Anthropol., North Texas State Univ ., Denton, TX76203, USA.

D80. Reefs and atolls

90:3927Acker, K.L. and C.W. Stearn, 1990. Carbonate

siliciclastic facies transition and reef growth onthe northeast coast of Barbados, West Indies. .T.sedim. Petrology, 60(1):18-25. 4306-16A St. SW,Calgary, AB TIT 4L5, Canada.

90:3928Siegrist, H.G. Jr. and R.H. Randall, 1989. Sampling

implications of stable isotope variation in Holocene reef corals from the Mariana Islands.Micronesica, 22(2):173-189.

The aim of this report is to point out sources, levels,and relative magnitudes of stable isotope variation incoral populations which can be expected whensampling emergent Holocene carbonate rocks. Atthe 'whole rock' level, both 813C and 8180 appear tofollow unimodal distributions among 8 genera acrossGuam and Pagan, but the curves are skewed towardmore negative values (apparently due to conversionto low Mg-calcite of a small portion of the specimens). There is a persistent increase in the experimental error introduced as the comparison levelchanges from between samples within the samecolony to between samples of different genera fromdifferent localities. This translates to a paraIlelincrease in the minimum difference between stableisotope values that could be detected at any specificprobability level. Dept. of Geol., Vniv. of Maryland,College Park, MD 20742, USA.

90:3929Woodroffe, Colin et al., 1990. Sea level and coral

atolls: Late Holocene emergence In the IndianOcean. Geology, geol. Soc. Am., 18(1):62-66.

A reexamination of coral conglomerates on theCocos (Keeling) Islands, which were first describedby Darwin, indicates that the islands have undergone at least 0.5 m of emergence over the last 3000yr. Radiocarbon ages on corals, the first radiometricHolocene dates obtained for islands in the easternand central Indian Ocean, combined with thepresence of elevated beachrock, coral fossils foundin microatolls above their upper growth limits, andmorphological evidence support this interpretation.Dept. of Geogr., Univ, of Wollongong, NSW,Australia. (hbf)

DllO. Erosion

90:3930Moore, J.G. et aI., 1989. Prodigious submarine

landslides on the Hawaiian Ridge. J. geophys.Res., 94(BI2):17,465-17,484.

610 D. Submarine Geology and Geoph ysics OLR (1990)31 (7)

Systematic mapping of the Hawaiian ExclusiveEconomic Zone, using side-looking sonar systemGLORIA within the extensive area covered by majorsubmarine mass wasting deposits on or near theHawaiian Ridge, shows that slumps and debrisavalanche deposits are exposed over 100,000 km2

and identifies 17 well-defined major landslides andremnants of several others. The report documentsthe characteristics of these landslides, examines theirmorphologic variations, and attempts to relate themto processes that built and modified the volcanicsystems of the Hawaiian Ridge. USGS, 345 Middlefield Rd. , MS 999, Menlo Park, CA 94025, USA.

D120. Sedimentary processes (deposition,diagenesis, etc.)

90:3931Behrmann, Gerhard, RUdiger Stein and J.-c.

Faugeres, 1989. Authigenic zeolites and theirrelation to silica diagenesis in ODP Site 661sediments (Leg 108, eastern equatorial Atlantic).Geologische Rdsch., 78(3):779-792 .

Based on chemical data, crystal size and shape andtheir intergrowth with associated mineral phases,two types of clinoptilolite occur representing different diagenetic conditions under which the formation of zeolites took place. Clinoptilolite type Awas found in a sediment section that comprisesnumerous hiatuses and stratigraphically condensedsediments and could have been formed during earlydiagenesis. In contrast, clinoptiloIite type B wasprecipitated in Campanian sediments during laterdiagenesis, after the transformation from opal-A toopal-CT had taken place. The silica source for theauthigenesis of both clinoptilolite types is biogenicopal. Alfred Wegener Inst. fur Polar- und Meeresfors., Columbusstr, 0-2850 Bremerhaven, FRO.

90:3932Gardner, W.D., 1989. Periodic resuspension in

Baltimore Canyon by focusing of internal waves.J . geophys. s«; 94(CI2):18,185-18,194.

In Baltimore submarine canyon, elevated concentrations that result from periodic resuspension eventsare often associated with a borelike intrusion of coldwater moving upslope near the canyon head. Bottomstresses generated in the canyon are sufficient toresuspend sediment along the axis between 200 and800 m. During resuspension events , the sedimentladen water is forced upcanyon, then sloshes backdown the canyon until it reaches a layer of

higher-density water, detaches from the canyonfloor, and moves seaward, trans ferring sediment andassociated pollutants to deeper water across theshelf-slope front. Dept. of Oceanogr., Texas A&MUniv., College Station, TX 77843, USA.

90:3933Hobert, L.A. and Andreas Wetzel, 1989. On the

relationship between silica and carbonate diagenesis in deep-sea sediments, GeologischeRdsch., 78(3):765-778.

Silica diagenesis and carbonate diagenesis arcinterrelated. Carbonate sediments con taining cherttend to be more indurated and display moreadvanced diagenetic alterations, regardless of subbottom depth; and microfossil components are morestrongly affected , while the amount of micriticparticles and larger, euhedral calcite crystals isgreater. In addition, mass physical properties, porosity in particular, vary more widely in sedimentsections containing chert. One possible mechanisminvolved is thc production of 'surplus' dissolvedcarbonate created by the replacement of carbonatematerial by silica during the process of cher tformation and silicification. The extra carbonate isthen available for precipitation as overgrowths andcement outside the chert nodules and silicified zones.13 Edgewood Ave., Albany, NY 12203, USA.

90:3934Muck, M.T. and M.B. Underwood, 1990. Upslope

flow of turbidity currents: a comparison amongfield observations, theory, and laboratory models.Geology, geol. Soc. Am ., 18(1):54-57.

The extent of upslope deposition by turbiditycurrents is related to flow thickness, tilt of thecross-flow surface slope, and a vertical shift in theflow's center of gravity. Field observations, numerical analysis, and laboratory experiments indicatethat the maximum run-up elevation is -1.53 timesflow thickness. Board of Earth ScL, Univ, ofCalifornia, Santa Cruz , CA 95064, USA. (bbf)

90:3935Ten Haven, R .L., J. Rullkotter and D.H. Welte,

1989. Steroid biological marker hydrocarbons asindicators of organic matter diagenesis in DeepSea [Drilling Project] sediments: geochemicalreactions and influence of different beat flowregimes. Geologische Rdsch.; 78(3): 841-850. Inst.fur Erdol und Organ. Oeochem., Kernforschung. lulich GmbH (KFA), Postfach 1913,D-5170 Julich , FRG.

OLR ( 1990) 37 (7) D. Submarine Geology and Geophy sics 611

D130. Sediments (rocks, formations, type,composition, etc.)

90:3936Bayer, Ulf and Andreas Wetzel, 1989. Compactional

behavior of fine-grained sediments- examplesfrom Deep Sea Drilling Project cores. Geologische Rdsch., 78(3):807-819.

Laboratory experiments, statistical analysis of fielddata and theoretical models are combined in theattempt to derive standard compaction curves forvarious deep-sea sediments which are in compactionequilibrium with the overburden. A revised andgeneralized version of Athy's law together withlaboratory experiments allows classification of sediments in terms of the amount of porewater structurally bound to the paricles' surfaces. Suctionpressure experiments, especially, are useful in quantifying the forces that bind water on particlesurfaces . The methods and equations required toderive the relevant parameters are given for downhole poros ity/density measurements and laboratoryexperiments. Inst. fur Erdol und organ. Geochem.,Kernforschung. Julich GmbH, Postfach 1913, D5170 Julich, FRG.

90:3937Beiersdorf, Helmut, 1989. Provenance and accumu

lation rates of Pliocene and Quaternary sedimentsfrom the western Coral Sea. Geologlsche Rdsch.,78(3):987-998.

Seven sediment cores were investigated from areas inthe western Coral Sea where Pliocene or Pleistocenestrata were reached at shallow depths. Calcareousbiological primary production is indicated since thePliocene . Younger Quaternary sections in two coresshow an abundance of siliceous microfossils resulting from influx of silica-rich water from the easternCoral Sea. The sediments have received terrigenouscomponents from mainland New Guinea and frommainland Australia, and the frequent fine-grainedvolcanic glass probably derived from volcaniceruptions in the southwest Pacific region . Bundesanstalt fur Geowissenschaften und Rohstoffe, Stilleweg2, 3000 Hannover 51, FRO.

90:3938Diester-Haass, Liselotte and Detmar Schnitker,

1989. Plio-Pleistocene sedimentation regimesleading to chalk-marl cycles in the North Atlantic(DSDP Site 552-Hole 552A). GeologischeRdsch., 78(3):959-985.

Pliocene sediments from the Rockall Plateau olderthan the onset of Northern Hemisphere glaciat ion

consist of calcareous oozes; younger Plio-Pleistocene sediments consist of ooze-marl cycles. Themarls are formed by addition of ice-raf ted detritus tomarine carbonates. Carbonate dissolution is tied tothe introduction of organic matter from surfacewater productivity, and dissolution cycles are outof-phase with peak occurrences of Antarc tic BottomWater which reflects bottom water circulation. Darkvolcanics are present in all glacial sediments. Lightash occurs in some interglacial and preglacialsediments; eolian transport is suggested for such ash.Univ. des Saarlandes, Fachrichtung Geogr., D-6600Saarbrucken, FRG.

90:3939Einsele, Gerhard, 1989. In-situ water contents, liquid

limits, -and submarine mass flows due to a highliquefaction potential of slope sediment (resultsfrom DSDP and subaerial counterparts). Geologische Rdsch., 78(3):821-840.

Water content-depth curves and Atterberg liquidlimits support the concept that many fine-grained,but low-cohesive thick slope sediments are susceptible to liquefaction, and therefore, as a result ofdynamic loading, can be transformed into mud flowswithout the uptake of additional water . This situation is particularly common in regions of highsedimentation rates, causing underconsolidation, aswell as in sediments rich in silt-size biogen icparticles . The examples presented are based onDSDP results and laboratory studies. Geo!. Inst.,Univ. of Tubingen, Sigwartstr. 10, D-7400 Tubingen,FRG.

90:3940Glass, B.P., 1989. North American tektite debris and

impact ejecta from DSDP Site 612 loff NewJersey). Meteoritics, 24(4):209-218.

A layer of tektite glass and shock-metamorphosedgrains found in upper Eocene sediments may belongto the North American tektite strewn field. However,the glasses generally have higher Kp and lowerNa20 contents for a given Si02 content and differentSr and Nd isotopic compositions. Tektite fragmentsare in an 8 ern thick layer; microtektites areconcentrated in the upper 4 ern, while microkrystitesare concentrated in the lower half of the layer. Rockand mineral grains showing evidence of shockmetamorphism are abundant in the upper half of thetektite-bearing layer. The size and abundance of thetektite glass and the abundance of shocked debrisindicate that Site 612 is relatively close to the sourcecrater, which may be to the north on the coastalplain or adjacent shelf. Dept. of Geol., Univ. ofDelaware, Newark, DE 19716, USA.


90:3941Minai, Y. and T. Tominaga, 1989. Neutron activation

analysis of rare earth elements in deep seasediments from tbe Pacific Ocean and the JapanSea. J. radioanalyt. nucl. Chem., (Letts)137(5):351-363. Dept. of Chern., Univ. of Tokyo,Hongo, Tokyo 113, Japan.

90:3942Nier, x.o, D.l. Schlutter and D.E. Brownlee, 1990.

Helium and neon isotopes in deep Pacific Oceansediments. Geochim. cosmochim, Acta, 54(1):173-182.

Magnetic particles collected in the deep Pacific arebelieved to be of extraterrestrial origin. Analyseswere made for samples consisting of composites ofmany extremely fine particles and for severalindividual particles large enough to contain sufficient gas for analysis but small enough to escapemelting in their passage through the atmosphere.Cosmic-ray spallation products or solar-wind heliumand neon, if present, were not abundant enough toaccount for the isotopic compositions measured. Thelow temperature extractions provided elemental andisotopic ratios in the general range found for theprimordial gas in carbonaceous chondrites andgas-rich meteorites; isotopic ratios found in the hightemperature extractions suggest the presence ofsolar-flare helium and neon. School of Phys. andAstron., Univ, of Minnesota, Minneapolis, MN55455, USA.

90:3943Rothe, Peter, 1989. Mineral composition of sedi

mentary formations in the North Atlantic Ocean.Geologische Rdsch., 78(3):903-942.

More than a thousand samples from the eastern andwestern North Atlantic were studied for theirmineral composition using x-ray powder diffraction.Specific mineral spectra were found for most of theformations. Changes in mineral composition alongformation boundaries are sharp in most cases, butalong some boundaries the change is transitional.Seismically mappable reflectors, calibrated at thesediment sequence of the drill sites, are in most casesrelated to lithological changes and mineral compositions which are often coincident with formationboundaries. Lehrstuhl fur Geol., Univ. Mannheim,Postfach 10 34 62, D-6800 Mannheim, FRG.

90:3944Wiesner, M.G., H.K. Wong and E.T. Degens, 1989.

Provenance and diagenesis of organic matter inLate Cretaceous and Tertiary sediments from thesouthern Black Sea margin. Geologische Rdsch.,78(3):793-806.

Organic matter in the Late Cretaceous-Tertiarysediments from the southern Black Sea margin isassigned to the terrestrial-marine/terrestrial range oforganic facies. Within this range, the stratigraphicsection yields different organic facies types inresponse to different accumulation and preservationcontrolling processes. The Late Cretaceous to Pliocene sediments are thermally immature. GeoLPalaontol, Inst. and Mus., Univ. Hamburg,Bundesstr. 55, n-zoco Hamburg 13, FRG.

90:3945Williams, A.T. and M.e. Thomas, 1989. S.E.M.

(scanning electron Dncroscopel analysis of quartzsand grains from selected Hong Kong andChinese littoral environments. Acta oceano!. sin.(English version), 8(3):409-422. Dept. of Sci. andChern. Engng, Polytech. of Wales, Pontypridd,Mid Glamorgan, CF37 lOL, UK.

90:3946Youn, J.-S., S.-B. Kim and G.-W. Koh, 1989.

Sedimentological characteristics of surface sediments in the southwestern sea off Cheju Island,Korea. J. oceanol. Soc. Korea, 24(3):132-147. (InKorean, English abstract.) Dept. of Oceanogr.,Cheju Natl. Univ., Cheju, Korea.

D140. Submarine hydrology (springs, hydrothermal deposits, etc.)

90:3947Auzende, l.-M. et al., 1989. Geological setting of an

active hydrothermal site: preliminary results ofthe STARMER 1 cruise of the submersibleNautiJe in the North Fiji Basin. C. r, Acad. Sci;Paris, (SeT. II)309(l8):1787-1795. (In French,English summary.)

Exploration of two areas of the active North FijiBasin axis near the 16040'S triple junction hasrevealed an active site, the White Lady, on the northend of the N 15° ridge, characterized by an activeanhydrite chimney, low chlorinity, 285°C temperature fluids, and colonies of gastropods, cirripeds,and mussels. At a second site within the graben atthe west end of the North Fiji fracture zone, there isevidence of former volcanic activity and activefissures. The northern wall of the graben displays acontinuous section of upper oceanic crust composedof massive flows, dike complex, and pillows.IFREMER-Brest, BoP. 70, 29263 Plouzane, France.

90:3948Erzinger, Jorg, 1989. Chemical alteration of tbe

oceanic crust. Geologische Rdsch., 78(3):731-740.


The uppermost basement is influenced by oxidativeseawater-basalt alteration at low temperatures andhigh water/rock ratios. With increasing crustal depthor even in a single pillow the temperatures rise, thewater/rock ratios become lower, the redox and pHvalues normally decrease, and the oxidative zone isfollowed by a non-oxidative one. Below these zonesthe basement has suffered high-temperature alteration under reducing and acidic conditions. Thisresults in chemical modifications of the rocks by theaddition or leaching of certain elements, and alsohas consequences for the composition of seawater.Inst. fur Geowiss. und Lithospharenforschung derJustus Liebig Univ., Senckenbergstr. 3, D-63ooGiessen, FRG.

90:3949Jean-Baptiste, P. et al., 1990.3He and methane in the

Gulf of Aden. Geochim. cosmochim. Acta, 54(1):111-116.

Significant 83He anomalies (up to 49%) exist over theWest Sheba Ridge. We conclude that the origin ofthis signal is independent from the well-knownhydrothermal 3He of Red Sea brines. Thus, activehydrothermalism occurs in this extensional basinassociated with spreading along an incipient midocean ridge. The 3He input from the Gulf of Adenaccounts for the S-N positive gradient in 3Heconcentration observed in the western part of theIndian Ocean. Methane anomalies are also present,but the CH4 and 3He signals are not systematicallycorrelated, suggesting complex production andconsumption mechanisms of methane in these areas.Lab. de Geochim. Isotopique, 91191 Gif-sur-Yvette,France.

D170. Historical geology, stratigraphy

90:3950Abbott, Dallas and William Menke, 1990. Length of

the global plate boundary at 2.4 Ga. Geology, geol.Soc. Am., 18(1):58-61. Lamont-Doherty GeoI.Observ., Palisades, NY 10964, USA.

90:3951Anderson, D.M. et al., 1989.Estimates of sea surface

temperature in the Coral Sea at the last glacialmaximum. Paleoceanography, 4(6):615-627.

CLIMAP (1981) reconstruction of the Coral Seafound little cooling (2 CO) in low latitudes, butwarming off Australia at _25°S. New core sites,oxygen isotope stratigraphy, and SST estimates usingthe modern analog technique confirm the CLIMAPconclusion that little or no temperature change

occurred in this tropical region at the last glacialmaximum, but in the 25°S region, two cores indicatetemperatures 3-4 Co colder than modern SST andremove the warm anomaly along the eastern coast ofAustralia. Dept. of Geol. Sci., Brown Univ., Providence, RI, USA.

90:3952Bloemendal, Jan and Peter deMenocal, 1989. Evi

dence for a change in the periodicity of tropicalclimate cycles at 2.4 Myr from whole-coremagnetic susceptibility measurements. Nature,Lond; 342(6252):897-900.

We show, from spectral analyses of the two susceptibility time series spanning the past 3.2-3.5 Myr,that the records are driven' strongly by orbitalforcing. Before 2.4 Myr before present, both recordsare strongly influenced by the 23- and 19-kyrperiodicities; after 2.4 Myr, both are significantlyinfluenced by the 41-kyr periodicity. This shiftcoincides with the beginning of major NorthernHemisphere glaciation, which indicates, for theIndian Ocean site, that the supply of terrigenoussediment has responded to the rapid increase in icecover at this time. We cannot, however, excludepossible effects of changes in bottom-water circulation on the susceptibility record of the Atlanticsite. Grad. School of Oceanogr., URI, Narragansett,Rl 02882, USA.

90:3953Brandon, M.T., 1989. Origin of igneous rocks

associated with melanges of the Pacific RimComplex, western Vancouver Island, Canada.Tectonics, 8(6):1115-1136. Dept. of GeoI. andGeophys., Yale Univ., New Haven, CT, USA.

90:3954Eyles, Nicholas and A.M. McCabe, 1989. The Late

Devensian «22,000 UP) Irish Sea Basin: thesedimentary record of a collapsed ice sheetmargin. Quat. Sci. Revs, 8(4):307-351. Dept. ofGeol., Univ. of Toronto, Scarborough, ON MIClA4, Canada.

90:3955Fallick, A.E. and PJ. Hamilton, 1989. The isotopic

geochemistry of ocean waters through time.Trans. R. Soc. Edinb., 80(3-4):177-181.

There is a general consensus that the global chemistry of ocean water has not changed markedlyduring the Phanerozoic. Nevertheless, significantchanges have occurred in the geochemical cycles ofsome elements and patterns of change have beenreconstructed through consideration of the isotoperatios I3C/12C, 34S/32S, 87Sr/86Sr, 14JNd/'44Nd,

614 D. Submarine Geology and G eophysics OLR (1990) 37 (7)

180 / 160 , and through measurements of D/H. Dissolved constituents in seawater display secularchanges in isotopic composition as a consequence ofquite different driving mechanisms. /lDC and 834Svariations are broadly correlated and linked bycarbon and sulphur exogenic cycle interactionthrough redox. reactions. The 87Sr /8GSr trend isdetermined by the balance among different Sr inputsto the oceanic pool; changes in 143Nd/ I44Nd areinfluenced by local erosion products from continental landmasses and can therefore be different forcoexisting palaeocean basins . Isotope Geol. Unit,Scottish Univ. Res. and Reactor Ctr., East Kilbride,Glasgow G75 OQU, Scotland, UK.

90:3956Haak, A.B. and Wolfgang Schlager, 1989. Compo

sitional variations in calciturbidites due to sealevel rJuctuations, Late Quaternary, Bahamas.Geologlsche Rdsch., 78(2):477-486 . Inst. of Earthsei, Free Univ., P.O. Box. 7161, 1007 MCAmsterdam, Netherlands.

90:3957Hequette, Arnaud and P.R. Hill, 1989. Late Qua

ternary seismic stratigraphy of the inner shelfseaward of the Tuktoyaktuk Peninsula, CanadianBeaufort Sea. Can. J. Earth Sci., 26(10): 19902002. Geol. Survey of Canada, Bedford Inst, ofOceanogr., P.O. Box 1006, Dartmouth, NS B2Y4A2, Canada.

90:3958Hess, Jennifer et al., 1989. The Oligocene marine

microfossil record: age assessments using stron tium isotopes. Paleoceanography, 4(6):655-679.

A strontium isotope record for the latest Eoceneearliest Miocene has been produced for Atlanticdeep-sea sequences from DSDP Atlantic sites 516F,563, and 529 and Pacific sites 77B, 292, and 593. Thecomposite 87Sr/86Sr age records of sites 516F and563, which have magnetostratigraphic age control,form a comprehensive, composite standard for theOligocene. Although some datum levels appear to besynchronous between the Atlantic and Pacific,results show that others are diachronous alonglongitudinal gradients. Grad. School of Oceanogr.,Univ . of Rhode Island, Narragansett, Rl 02882,USA.

90:3959Heusser, C.J., 1989. Climate and chronology of

Antarctica and adjacent South America over thepast 30,000 yr. Palaeogeogr, Palaeoclimatol .Palaeoecol; 76(1-2):31-37.

Close-interval dating of a pollen record at Harberton

in southern Tierra del Fuego indicates a climaticparallel with isotope temperature/climate da ta developed from Antarctic ice cores. Over the time spanof -30,000 yr since before the full glacial, coldestconditions both in Antarctica and South Americaappear centered at 20,000 yrBP. Warming of climateoccurred ill the late glacial after 15,000 yrBP,interrupted by a cold episode between about 13,000and 10,500 yrBP, with maximum warmth at 9000yrBP in the Early Holocene, after which temperatures were lower, varying only moderately until thepresent. Dept. of Biol., New York Univ., 1009 MainBldg., New York, NY 10003, NY, USA.

90:3960Hiscott, R.N. et al., 1990. Comparative stratigraphy

and subsidence history of Mesozoic rift basins ofNorth Atlantic. Am. Ass. Petrol. Geol. Bull;74(1):60-76.

Mesozoic rift basins around the North Atlanticpossess many common Upper Jurassic-Lower Cretaceous stratigraphic elements, as well as localfeatures . Decompaction and backstripping of sediments from well and outcrop sections in six basinsalso reveal broad similarities in trends of basementsubsidence rates. Relatively high subsidence ratescharacterize onset of rift phases in the Triassic andKimmeridgian. A third phase of rapid subsidence inthe Cantabrian and Aquitaine basins may be due totranstensional stresses or gravi ty-driven partialcollapse of the new continental margin. The basinsshare a common origin controlled by intracontinental rifting and the subsequent separation ofEurope and North America. Superimposed on theirrecord of pulses of extension are the effects ofeustatic sea level variations. Dept. of Earth Sci.,Memorial Univ. of Newfoundland, St. John's, NFALB 3X5, Canada.

90:3961Hudson, J.D. and T.F. Anderson, 1989. Ocean

temperatures and isotopic compositions throughtime. Trans. R. Soc. Edinb., 80(3-4):183-192.

Fossil assemblages can give quantitative estimates ofpalaeotemperatures, by comparison with modernbiota, only in the recent geological pas t. Oxygenisotopic palaeotemperatures on calcareous or phosphatic fossils are potentially available for the wholePhanerozoic. Their reliability is limited by physiological effects , preservation, and by uncertainty inthe isotopic composition of ancient seawater. In theMesozoic, reasonable assumptions about oceanisotopic composition lead to palaeotemperatureestimates that suggest generally higher temperaturesthan at present, part icularly for mid- to highlatitudes. This agrees with estimates based on biotic

OLR (1990)37(1) D. Submarine Geology and Geophysics 615

distributions. Late Palaeozoic glaciation is reflectedin variable isotopic compositions in high palaeolatitude areas. In the earlier Palaeozoic, wellpreserved fossils indicate either oceans enriched in160 compared to today's or generally higher temperatures; controversy continues about the relativeimportance of the two effects. Dept. of Geol., Univ.of Leicester, LEI 7RH, UK.

90:3962Isla, F.L, 1989. Holocene sea-level fluctuation in the

Southern Hemisphere. Quat. Sci. Revs, 8(4):359368.

If rising sea levels dominate the Northern Hemisphere, falling or fluctuating sea levels predominatein the Southern Hemisphere. Evidence from SouthAmerica, Africa, Antarctica, Australia and thePacific and Indian oceans suggest that the Holocenetransgression rose above the present MSL in higherlatitudes before it rose in the tropics . Climate couldbe the only factor responsible for this hemisphere wide behavior of MSL. It has been suggested thatthe climate of the SH precedes that of the NH by3000 years. The climatic optimum, or maximumwarmth, occurred predominantly about 6000 BP inthe NH, but about 10-9000 BP in the SH. Short-termclimatic effects on the sea level should havesignificant occurrences during the past in thewindiest oceanic hemisphere. This latitudinal trendin former MSL should be considered when usingshorelines as reference points for measuring verticalcrustal movements. CONICET, Ctr . de Geol. deCostas c.c. 722, 7600 Mar del Plata, Argentina.

90:3963Koeberl , Christian, 1990. Kara and Ust-Kara impact

structures (USSR) and their relevance to the KITboundary event. Geology, geol. Soc. Am., 18(1):50·53.

New 4OArP9Ar and K-Ar dating of the Kara andUst-Kara impact structures place the impact eventat slightly more than 70 Ma, roughly coincident withthe Campanian/Maastrictian boundary and olderthan the 66 Ma K/T boundary. It is suggested thatthe twin craters , with estimated maximum diametersof 60 km and 70 km, represent a substantial impactevent that could have initiated an in terval of majordegradation of the biosphere. Lunar and PlanetaryInst., 3303 NASA Rd. One, Houston, TX 77058,USA.

90:3964Kuijpers, Antoon, 1989. Southern Ocean circulation

and global climate in the Middle Pleistocene(Early Brunhes). Palaeogeogr. Palaeoclimatol.Palaeoecol., 76(1-2):67-83.

Compilation of published data has enabled reconstruction of the Middle Pleistocene (0.7-0.4 myBP)Southern Ocean circulat ion regime; possible linkswith Northern Hemisphere climate are indicated. Inthe Southern Ocean, a stronger Circumpolar Currentand enhanced Antarctic Bottom Water formationare indicative of low pycnocline stability. EnhancedSouthern Ocean convection is assumed to have beenlinked to a change of North Atlantic Deep WaterT/S signatures. A large Antarctic ice volume,ascribed to increased precipitation, would explainlower interglacial sea level stands, and larger floatingice shelves would favor Antarctic Bottom Waterformation, Ministry of the Environ., Dept. of Mar.Resour., Nat! Forest and Nature Agcy., Slotsmarken13, DK 2970 Horsholm, Denmark.

90:3965Kyte, F.T., D .M. Triplehorn (comments) and Birger

Schmitz (replies), 1990. [Discussion of) 'Origin ofmicrolayering in worldwide distributed Ir-riehmarine Cretaceous/Tertiary boundary clays.'Geology, geol. Soc. Am., 18(1) :87-94.

90:3966Labracherie, Monique et al., 1989. The last degla

ciation in the Southern Ocean. Paleoceanography,4(6): 629-638.

The isotopic and micropaleontological deglacialrecords of three deep-sea cores from 44°8 to 55°Shave been dated by accelerator mass spectrometry.By 13,000 yrBP SSTs reached values similar topresent values. A cool oscillation abruptly interrupted this warm phase between 12,000 and 11,000yrBP. Initiation of this cooling therefore precededthe Northern Hemisphere Younger Dryas by-wooyr. Complete warming was reached by 10,000 yrBP,more or less synchronous with the northeast AtlanticOcean. Dept. de Geol. et Oceanogr., Univ. deBordeaux 1, Talence, France.

90:3967Meng, Guanglan, Yousong Han and Shaoqing

Wang, 1989. Late Quaternary sporopoUen assemblages and their geological significance in tbeCbangjiang River mouth area of the East ChinaSea. Mar. Geol. Quat. Geol., 9(2): 13-26. (InChinese, English abstract.) Inst. of Oceanol.,Acad, Sinica, Qingdao, People's Republic ofChina,

90:3968Partridge, T.C. and R.R. Maud, 1989. The end

Cretaceous event: new evidence from the Southern Hemisphere. S. Afr. J. sa, 85(7) :428-430.

Mass extinctions, coupled with the appearance of


many new species and a variety of physical phenomena, are associated with the KIT boundary inthe Northern Hemisphere. In the Southern Hemisphere in Australia and southern Africa, a regionallyextensive silcrete duricrust overlying a deeply weathered profile appears to be coeval with K/T boundaryphenomena. It is suggested that the deeply kaolinized soil profiles developed under the Late Cretaceous humid, tropical climate, and that extraterrestrial impact or volcanism at the K/T boundaryfavored further lowering of pH and uptake of silica.A subsequent prolonged desiccation would thenha.ve produced extensive silcrete precipitation. Theevidence from the Southern Hemisphere implieschanges of a sustained nature, more likely associatedwith volcanism than with a series of impacts. Dept.of Palaeontol. and Palaeoenviron. Studies, TransvaalMus., P.O. Box 413, Pretoria 0001, South Africa.(hbf)

90:3969Petit, J.R. et al., 1990. Palaeoclimatological and

chronological implications of the Vostok core dustrecord. Nature, Lond; 343(6253):56-58.

Here we present and discuss the dust recordo~tained down to 2,202 m, the final depth to whichthis core was extended in 1986. Major changes inaeolian deposits, as recorded in the Vostok coreappear to be of global significance and confirm theexistence of a link between high-latitude aeoliandeposits and the Earth's orbital parameters. Atmospheric dust is proposed as a stratigraphic marker tocompare timing with other records of paleoclimate;the magnetic-susceptibility profile measured alongthe RCIJ-120 Indian Ocean core is used for thispurpose, assuming that major dust events corre~po~d to common aeolian inputs. This approachindicates that the Vostok and marine records wereroughly in phase at the p.revious glacial-interglacialt~ansltJon. Lab. de Glaciol, et Geophys. de l'Environ., BP 96, 38402 St. Martin d'Heres, Cedex,France.

90:3970Stein, R., J. Rullkotter and D.H. Welte, 1989.

Changes in paieeenvironmeuts in the AtlanticOcean during Cretaceous times: results fromblack shales studies. Geologische Rdsch., 78(3):883-901.

Calculations of accumulation rates of marine andterrigenous organic carbon, organic carbon-sedimentation rate relationships, and estimates of paleoproductivity show that both the amount and typeof organic matter in Atlantic black shales changed~arkedly with location and age, indicating thatdifferent factors-terrigenous organic matter supply,

increased oceanic productivity, increased preservation. i~ anoxic environments, and rapid burial byturbldlte~ cause~ the accumulation of these organiccarbon-rich sediments, Inst. fur Geowissenschaftenund Lithospharenforschung, Univ, Giessen,Senckenbergstr, 3, 6300 Giessen, FRO.

90:3971Trego, K.D., 1989. Multiple impacts in the Earth's

cratering history. Earth, Moon, Planets, 46(3):201-205.

Increased impact fluxes on Earth may be associatedwith the orbital decay of captured Apollo objects.!h~ two Messier impact~tructures on the Moon mayindicate that the breaking up of a large object isresponsible for multiple impacts on Earth at theCretaceous/Tertiary boundary. Planetol. Res. Inst.,Palto Alto, CA, USA. (fcs)

90:3972Vermeij, G.J., 1989. Geographical restriction as a

guide to the causes of extinction: the case of thecold northern oceans during the Neogene. Paleobiology, 15(4):335-356.

This ~aper represents an attempt to analyze thepervasrve phenomenon of background extinctionwhich until recently has been largely ignored i~favor of the great mass extinctions. A synthesis ofdata on the geographical and stratigraphical distributions of cool-water molluscs of the NorthPacific and North Atlantic oceans during the LateNeogene reveals four patterns of geographicalrestriction, at least two of which imply that climaticcooling was not the only cause of extinction duringthe last several million years. The patterns provideadditional support to previous inferences that reductions in primary productivity have played asi~icant role in marine extinctions. Dept. of Geol.,Univ. of California, Davis, CA 95616, USA.

90:3973Wittbrodt, P.R., D.B. Stone and D.L. Turner, 1989.

Paleomagnetism and geochronology of St. Matthew Island, Bering Sea. Can. J. Earth Sci;26(10):2116-2129. Geophys, Inst., Univ, of Alaska, Fairbanks, AK 99775-0800, USA.

90:3974Wright, H.E. r-, 1989. The amphi-Atlantic distri

bution of the Younger Dryas paleoclimatic oscillation. Quat. Sci. Revs, 8(4);295-306.

The Allerod/Younger Dryas event is well established in western Europe. In North America recentpollen and lithostratigraphic investigations in theCanadian Maritime Provinces and in the till plains


of west central Ohio indicate that the event also lefta record in eastern North America. A leadinghypothesis for the cause of Younger Dryas coolingappeals to the influx of tabular icebergs releasedfrom wasting Scandinavian and Siberian ice sheetsduring Allerod warming. In North America theYounger Dryas is associated with a major diversionof drainage. The interval was terminated when, withthe final retreat of the ice, drainage again went to theeast, and warming was renewed. Limno!. Res. Ctr.,Univ. of Minnesota, Minneapolis, MN 55455, USA.

D180. Paleontology (see also E-BIOLOGICAL

OCEANOGRAPHY)

90:3975Berggren, W.A. and K.G. Miller, 1989. Cenozoic

bathyal and abyssal calcareous benthic foraminiferal zonation. Micropaleontology, 35(4):308320.

Dur ing the past ten years, study of deep-sea benthicForaminifera has provided an improved taxonomicbase and empirical observations of age--depth distributions. Building on this data base, we establish 14bathyal and 12 abyssal zones for the Cenozoic deepsea. Biostratigraphic resolution is higher in theabyssal realm during the Paleogene and higher in thebathyal realm during the Neogene. During periodsof accelerated taxonomic turnover deep-sea benthicForaminifera yield fairly refined zonations; incontrast, slow taxonomic turnover occurred duringthe Paleocene in the bathyal and abyssal realms andin the Late Neogene in the abyssal realm, yieldingfew biostratigraphic subdivisions. WHOI, WoodsHole, MA 02543, USA.

90:3976Blanc-Vernet, L. and F. Sgarrella, 1989. Planktonic

foraminiferal assemblages in the Tyrrhenian Seaand the Adriatic Sea during the last 130,000years. Paleoecological implication. Palaeogeogr.Palaeoclimatol. Palaeoecol; 76(1-2):107-124.

Planktonic foraminiferal assemblages in three Tyrrhenian Sea cores and in one Adriatic Sea coreprovide a climatic sequence from the last interglacialto the Holocene. The data have been treated by theCorrespondence Factor Analysis method. Alternation of Atlantic subtropical species with an Atlantictemperate form is interpreted as reflecting circulation changes in tbe Atlantic. In the TyrrhenianSea, the postglacial planktonic microfauna is homogeneous, but during stage 5 there are differencesbetween southern and northern assemblages, suggesting that circulation was different during these

two warm periods. In the Adriatic, a hydrologicalshift at ~25,OOO yrBP is indicated. Ctr. d'Oceano\.de Marseille, Fac, des Sci. de Luminy, 13288Marseille Cedex 9, France.

90:3977Bleil, Ulrich and Gunilla Gard, 1989. Chronology

and correlation of Quaternary magnetostratIgraphy and nannofossil biostratigraphy in Norwegian-Greenland Sea sediments. GeologischeRdsch ., 78(3): I173-1187.

Paleomagnetic analyses document the existence ofseven short-lived geomagnetic events during the last-500 kyr. Calcareous nannofossil biostratigraphy,correlated to oxygen isotope chronostratigraphy,provides a time framework to infer age and durationof these periods of extreme divergence of the earth'smagnetic paleofield from the regular normal polarityconfiguration of the Brunhes Chron. FachbereichGeowiss., Univ. Bremen, Postfach 330 440, D-2800Bremen 33, FRG.

90:3978Brunner, C.A. and M.T. Ledbetter, 1989. Late

Quaternary quantitative planktonic foraminiferalbiostratigraphy in turbidite sequences of thecentral California continental margin. Micropaleontology, 35(4):321-336.

A latest Pleistocene-Holocene biostratigraphy isconstructed in seven cores from Monterey andOelgada fans. Q-mode cluster analysis clusteredsamples into four groups of planktonic foraminiferswhich were used to define three assemblage zones.After exclusion of samples with mud turbiditecomponents, the sediment sequences exhibit apattern of assemblage succession that is coherentbetween the two fans. A brief cooling within thedeglaciation interval may be the correlative of theYounger Dryas event of the North Atlantic Basinand northern Europe. Dept. of Geol, Sci., CaliforniaState Univ., Hayward, CA 94542, USA.

90:3979Clarkson, E.N.K., G.B. Curry and W.O.I. Rolfe

(organizers), 1989. Environments and physiologyof fossil organisms. Symposium proceedings, TheRoyal Society of Edinburgh, 28-30 September1988. Trans. R. Soc. Edinb.; 80(3-4): 167-329; 17papers.

The reports presented relate either to the evolutionof the Earth's environment through time or tophysiological responses of organisms to environmental change. The section on the changing environment considers the isotopic geochemistry of theoceans, ocean temperatures, biomineralization, and

618 D. Submarine Geology and Geophysics OLR ( 1990) 37 (7)

comparative physiology as a tool for understandingthe evolution of land animals. The section onphysiological adaptations considers evidence fromthe prokaryotes, agnathans, brachiopods, crustaceans , Chelicerata, vertebrates, and land plants , aswell as general physiological constraints on marineorganisms, the concept of a brackish-water fauna ,adaptations to extreme pressures, and the significance of Burgess Shale-type faunas. (hbf)

90:3980Delaney, M.L. et al., 1989. Lithium-to-calcium ratios

in modem, Cenozoic, and Paleozoic articulatebrachiopod sheDs. Paleoceanography, 4(6):681691.

Li/Ca ratios in modem brachiopod shells generallycorrelate inversely with growth temperature rangingfrom ~20 to -50 p.mollmo1. Cenozoic ratiosaverage -30 p.mollmol, similar to the averageobserved in modern brachiopods. Relatively conslant LiICa ratios for Eocene to Pleistocene nonluminescent brachiopod shells support the conclusion of little variation in Cenozoic seawater Li/Ca,Nonluminescent Permian and Carboniferous brachiopods have Li/Ca ratios substantially lower thanmodem, Cenozoic, or Devonian samples. Low Liconcentrations in Permo-Carboniferous seawatercould be the result of a lower flux of dissolved Lifrom the continents andlor a higher flux fromseawater to clastic marine sediments. lnst. of Mar.Sci., Univ. of California, Santa Cruz, CA, USA.

90:3981Denne, R.A. and B.K. Sen Gupta , 1989. Effects of

taphonomy and habitat on the record of benthicForaminifera in modem sediments. Palaios, 4(5):414-423.

Analysis of the distribution of foraminifers in tencores from the northwestern Gulf of Mexico indicatethat reported differences in the distribution ofmodem benthic species can be explained by differences in sampling interval (l em versus 2-5 cm).Further, the data do not support the commonassumption that the distribution of species is homogeneous within the bioturbated zone. It is suggested that modem distribution patterns, as observed within 5-10 em-thick surface sediment layers,provide a better comparative basis for studies ofbenthic foraminiferal paleoecology. Dept. of Oeol.and Geophys., Louisiana State Univ., Baton Rouge,LA 70803, USA. (hbf)

90:3982Haake, F.-W. and Uwe Pflaumann, 1989. Late

Pleistocene foraminiferal stratigraphy on theVmng Plateau, Norwegian Sea. Boreas, 18(4):

343-356. Geol. Palaont. lust. der Univ, Kiel,Olshausenstr. 40-60, D-23oo Kiel, FRG .

90:3983Hald, Morten, T.K. Danielsen and Stein Lorentzen,

1989. Late Pleistocene-Holocene benthic foraminiferal distribution in the southwestern BarentsSea: paleoenvironmental implications. Boreas,18(4):367-388. Univ. of Trornso, Inst. of BioI.and Geol., N-900l Tromso, Norway.

90:3984Holman, E.W., 1989. Some evolutionary correlates of

higher taxa. Paleobiology, 15(4):357-363.

Nonparametric randomization tests were used todetermine whether fossilmarine families classified indifferent higher taxa are significantly different intheir durations, their rates of origination andextinction, and their proportion of originations. Foreach of these properties, significant differencesamong orders and classes were found that could notbe explained by differences at other taxonomicranks, but no such differences were found amongphyla. Thus, orders and classes appear to possess anevolutionary coherence that phyla lack. Dept. ofPsychol ., Univ. of California, Los Angeles, CA90024, USA.

90:3985Jasper, J.P. and R.B. Gagosian, 1989. Alkenone

molecular stratigraphy in an oceanic environmentaffected by glacial freshwater events. Paleoceanography, 4(6):603-614.

The sedimentary record of a ratio (UK37) of longchain (Cn) unsaturated alkenones is a useful indicator of glacial-interglacial climatic change in theLate Quaternary northern Gulf of Mexico where aplanktonic foraminiferal isotopic record is complicated by meltwater and fluvial events. Application ofa laboratory temperature calibration of the UK37ratio to a core record suggested that the minimumglacial surface mixed layer (SML) temperature was80 ± 1DC colder than the Holocene high SMLtemperature of 25.6° ±O.5°C, significantly largerthan the differences predicted by either the foraminiferal 8180 or foraminiferal assemblage temperature methods. This large difference may be causedby a combination of local Prymnesiophyte assemblage changes in response to climatically inducedhydrographic changes and depth of alkenone biosynthesis. Dept. of Chern. and Geol. , Indiana Univ.,Bloomington, IN, USA.

90:3986Jones, I .R., Barry Cameron and H.B. Rollins, 1989.

Paleoecological implications of cohort survivorship for Mya arenar;a in Massachusetts estuarine


waters. Palaios, 4(5):468-474. Dept. of Geo!.,Acadia Univ., Wolfville, NS BOP IXO, Canada.

90:3987Kuhnt, Wolfgang, M.A. Kaminski and Michel

Moullade, 1989. Late Cretaceous deep-wateragglutinated foraminiferal assemblages from theNorth Atlantic aod its marginal seas. GeologischeRdsch., 78(3): 1121-1140. Geo!. Inst. der Univ .Tubingen, Sigwartstr. 10, D-7400 Tubingen,FRG.

90:3988Locker, S. and E. Martini, 1989. Phytoliths at DSDP

Site 591 in the southwest Pacific and thearidification of Australia. Geologlsche Rdsch.;78(3):1165-1172. Geo!.-PalaontoL Inst. derUniv., Olshausenstr. 40/60, D-2300 Kiel, FRG.

90:3989Morris, S.C., 1989. The persistence of Burgess

Shale-type faunas: implications for the evolutionof deeper-water faunas. Trans . R. Soc. Edinb.,80(3-4):271-283.

Discoveries in >30 Lower and Middle Cambrianhorizons with soft-bodied fossils have shown thatforty-one of the genera occur also in the BurgessShale. Significantly, they tend to have lengthystratigraphic durations (from early Lower Cambrianto end of the Middle Cambrian) ; at least somegenera also have wide geographical ranges. A fewgenera may have been pelagic, but these distributions are mostly explained in terms of a deeperwater biota with an evolutionarily conservativeaspect. Both the origins and further recruitment tothis biota may have been from shallower water, withmore limited in-situ diversification. It is speculatedthat this distinctive Cambrian biota was graduallydriven to extinction with the arrival of Ordoviciancompetitors, although some relics may have surviveduntil at least the Devonian. This history hasimplications for our understanding of deeper-waterfaun as throughout the Phanerozoic, and supports thenotion that archaic forms may take refuge in thisenvironment. Dept. of Earth Sci., Univ. of Cambridge, Downing St., Cambridge CB2 3EQ, UK.

90:3990Riegraf, Wolfgang, 1989. [Benthic shelf Foraminifera

of the Valanginium-Hauterivium (Lower Cretaceous) of the Indian Ocean southwest of Madagascar (Deep Sea Drilling Project Leg 25, Site249).' Geologische Rdsch., 78(3):1047-1061. (InGerman, English abstract.) Hollandtstr. 55,D-4400 Munster I, FRO.

90:3991Riegraf, Wolfgang and Hanspeter Luterbacher,

1989. [Benthic Foraminifera of the Lower Cretaceous: Deep Sea Drilling Project (Leg 1-79).1Geologische Rdsch; 78(3) :1063-1120. (In German, English abstract.) Inst. fur Geol, undPalaontol. der Univ. Tubingen, Sigwartstr. 10,D-4700 Tubingen 1, FRO.


1989. Jurassic and Cretaceous rhyncholites (cephalopod jaws) from the North Atlantic Ocean(Deep Sea Drilllng Project Leg 1-79) and theirEuropean counterparts. Evidence for the uniformity of the western Tethys. GeologischeRdsch; 78(3):1141-1163. Hollandstr. 55, D 4400Munster, FRO.


1989. [Upper Jurassic Foraminifera of the Northand South Atlantic (Deep Sea Drilling ProjectLeg 1-79).1 Geologische Rdsch., 78(3):999-1045.(In German, English abstract.) Hollandstr. 55, D4400, Munster, FRO.

90:3994Sims, P.A., G.A. Fryxell and J.G. Baldauf, 1989.

Critical examination of the diatom genusAzpeitia: species useful as stratigraphic markersfor the Oligocene and Miocene epochs. Micropaleontology , 35(4):293-307. Dept. of Bot., British Mus . (Nat. Hist.), Cromwell Rd., LondonSW7 5BD, UK.

90:3995Spero, H.I. and D.F. Williams, 1989. Opening the

carbon isotope 'vital effect' black box. 1. Seasonaltemperatures in the euphotic zone. Paleoceanography, 4(6):593-601.

Reconstruction of seasonal temperatures using 8180

and c'j13C data from individual Holocene Orbulinauniversa from western equatorial Pacific Oceanboxcore ERDC-83 yields ranges of 23.5-29.9°C and20.l-24.5°C for the shallow and deep euphotic zonerespectively , in excellent agreement with recenttemperature measurements. Analyses of individual,late glacial (R:: 12,000-13,000 yrBP) O. universa fromthis site suggest the seasonal upper euphotic zonetemperature range was ~2.5 CO lower than today, afunction of cooler summers. Mar. Sci. Inst., Univ. ofCalifornia, Santa Barbara, CA, USA.

620 D. Submarine Geology and Geophys ics OLR {I 990)37 (7)

0200. Gravity, geodesy, magnetism

90:3996Arkani-Hamed, Jafar, 1989. Tbennoviscous rema

nent magnetization of oceanic Iithospbere inferredfrom its thermal evolution. J. geophys. Res;94(B12):17,421-17,436.

Magnetization models of oceanic lithosphere aredeveloped using both thermal remanent magnetizat ion and viscous remanent magnetization contributions (Arkani-Hamed, (988), both of which areassumed to be dependent on temperature. Themodels are then evaluated by comparing the skewness of their magnetic anomalies to those observedat sea level and satellite altitudes. The resultantremanent magnetization patterns of the oceaniclithosphere give rise to anomalies similar to thoseobserved by Magsat over the Cretaceous quiet zonesof the Atlantic and by marine magnetic surveys overanomaly 33. Dept. of Geo!. Sci., McGill Univ.,Montreal, PQ H3A 2A7, Canada.

90:3997Bloxham, J., D. Gubbins and A. Jackson, 1989.

Geomagnetic secular variation. Phil. Trans. R.Soc; (A)329(1606):415-502.

Maps of the core-mantle boundary at ~60-yr

intervals for the 1700s and 1800s and at lO-yrintervals during the 1900s (based on 175,000 magnetic observations) show that secular variations tendto be low beneath the Pacific and rapid beneathsouthern Africa and the South Atlantic. The morphology of the static field supports a model of asimple dynamo with two ma in high-latitude concentrations of flux in each hemisphere. Some of theevidence throws into question the validity of flowmaps . Chapters cover the data and method used,results, the core field and its changes , the frozen-fluxhypothesis, core motions, diffusion, the dynamo,interaction with the lower mantle, and generalconclusions. Dept. of Earth and Planet. Sci., Harvard Univ., 20 Oxford St., Cambridge, MA 02138,USA. (hbf)

90:3998Caress, D.W. and R.L. Parker, 1989. Spectral

interpolation and downward continuation of marine magnetic anomaly data. J. geophys, Res.,94(B12):17,393-17,407.

An algorithm for interpolation and downwardcontinuation of magnetic anomaly data works withina statistical framework. We assume that the magnetic anomaly is a realization of a random stationaryfield whose power spec tral density (PSD) we canestimate; by using the PSD the algorithm produces

an array incorporating as much of the informationcontained in the data as possible while avoiding theintroduction of unnecessary complexity. The algorithm has the added advantage of estimating theuncertainty of every interpolated value. Downwardcontinuation is a natural extension of the statisticalalgorithm. Scripps lost. of Oceanogr., La Jolla, CA92093, USA.

90:3999Geiss, E., N. Petersen and U. Bleil, 1989. Amplitude

variation of marine magnetic anomalies. Geologische Rdsch; 78(3):741-752.

Eight profiles across the Mid-Atlantic Ridge, fiveacross the East Pacific Rise, and three across theIndian Ocean were analyzed to determine thelarge-scale amplitude variation of marine magneticanomalies. Model calculations support a three-layermodel for the sources of marine magnetic anomalies:an uppermost layer of 1000 m basalt with agedependent magnetization and two layers, corresponding to seismic layers 3A and 3B, with ageindependent magnetization . The most likely causefor age-dependency of magnetization of the uppermost layer of oceanic basalts is gradual lowtemperature oxidation of the magnetic mineralscontained in the rocks. Dt. Geodat. Forschungs.,Abt. 1. Theoret. Geod., Marstallp1atz 8, D-8000Munchen 22, FRG.

90:4000Hildebrand, J.A., 1989. The paleomagnetism of

eastern Nazca Plate seamounts. Tectonophysics,170(3-4):279-287_

Magnetic and bathymetric surveys of two seamountsin the Chile Basin are used to calculate paleomagnetic poles with uniform and nonuniform magneticmodeling. The paleopole for Piquero-2 seamount iscoincident with the earth's pole, suggesting a youngseamount. The paleopole for Piquero-I seamountindicates that the Nazca Plate moved 23° northwardduring 0-50 Ma, considerably more motion thanpredicted. Inst. of Mar. Resour., A-005, Scripps lost.of Oceanogr., La Jolla, CA 92095, USA.

90:4001Matsushirna, Masaki and Yoshimori Honkura, 1989.

Large-scale Duid motion in the Earth's outer coreestimated from non-dipole magnetic field data. J.Geomagn. Geoelect; 41(1l) :963-IOOO. Dept. ofAppl. Phys., Tokyo Inst, of Tech., Tokyo 152,Japan.

90:4002Pozzi, l.-P. and Tahar Alfa, 1989. Effects of exper

imental deformation on the remanent magnetl-


zation of sediments. Phys. Earth planet. Interiors,58(2-3):255-266.

Changes in direction and in intensity of the remanent magnetization of sediments were studied duringexperimental deformation leading to an axial shortening of 20--30%. The results show that the directionof magnetization is stable during the deformationwithin the experimental precision. The intensity ofmagnetization decreases during shortening by anamount which depends on the type of rock: about30% for sandstones and about 5% for marls andvolcanic sediments. An interpretation is given after adiscussion of the results obtained by other authorswith plasticine and artificial clays. The amplitude ofthe decrease and of the rotation of the remanentmagnetization could be a function of the size of themagnetic grains compared with the scale of fracturing during non-homogeneous processes of deformation. Ecole Normale Superieure, Dept. deGeol., 24 Rue Lhomond, 75231 Paris Cedex 05,France. .

90:4003Raju, K.AK. and T. Ramprasad, 1989. Magnetic

lineations in the central Indian Basin for theperiod A24-A21: a study in relation to the IndianOcean triple junction trace. Earth planet. Sci.Letts, 95(3-4):395-402.

A detailed study of magnetics and bathymetry wascarried out between 90S and 16°30'S and 73°E and79°30'E. Observed east-west trending magneticanomalies are identified as anomalies 21 to 25. Themagnetic lineation pattern revealed a new fracturezone at 75°45'E trending N12°E which runs parallelto the 86c E fracture zone and appears to changedirection south of 200S. Differential offsets observedin identified magnetic anomalies across the newfracture zone are explained in terms of evolution ofthe triple junction. The study also confirms the strikeof the 79°E fracture zone and its southern extensionthrough the study area. Natl. Inst. of Oceanogr.,Dona Paula, Goa 403 004, India

90:4004Rapp, R.H., 1989. The decay of the spectrum of the

gravitational potential and the topography for theEarth. Geophys, J. int; 99(3):449-455.

The spectrum of the Earth's gravitational potentialand topography, as represented by spherical harmonic expansions to 180°, have been computed.Modeling the decay in the form of AI-Il values of Aand f3 for several degree (I) ranges were computed.The values imply that potential decays faster athigher I values. Values of f3 for topography werefairly uniform around 2, which agrees with a

suggestion of Vening-Meinesz (1951), and the f3value for the Earth's potential agrees well with thevalue implied by topography with Airy isostaticcompensation at a depth of 30 km, However, themagnitude of the power implied by the topographic/isostatic potential was -113 of observed potential. Dept. of Geodetic Sci. and Surveying, OhioState Univ., Columbus, OH 43210, USA.

90:4005Sempere, J.-C. et al., 1989. Three-dimensional inver

sion of the magnetic field over the Easter-Nazcapropagating rift near 25°8, llr2S'W. J. geophys, Res., 94(B12):17,409-17,420.

The Easter microplate boundary configuration isbeing reorganized by rift propagation. A 3-Dinversion of the magnetic field over the propagatingrift tip area suggests that the western and easternpsuedofaults strike 14° and 338° respectively, andconverge near the rift tip at a spreading rate ratio of1.5, consistent with a propagation rate of 120mm/yr. The magnetization distribution exhibits ahigh at the propagating rift tip. Preliminary rockmagnetic measurements of basalts recovered nearthe rift confirm the presence of highly magnetizedbasalts but suggest that the relationship betweenhigh magnetization intensities and high Fe content isnot straightforward. School of Oceanogr., WB-IO,Univ. of Washington, Seattle, WA 98195, USA.

90:4006Small, Christopher and D.T. Sandwell, 1989. An

abrupt change in ridge axis gravity with spreadingrate. J. geophys, Res., 94(BI2):17,383-17,392.

An analysis of 44 Geosat vertical deflection profilesover ridges with spreading rates of 14 to 155 mm/yrfinds that slow spreading ridges usually have highamplitude gravity troughs (40-100 j.trad = 40-100mGal), whereas fast spreading ridges are characterized by low-amplitude ridge axis highs (-15p.rad). The transition from axial trough to axial highoccurs abruptly at a spreading rate of 60-70 mm/yr,The transition of the gravity signature appears to bemore abrupt than the transition of the topographicsignature. Published models of ridge axis dynamicsdo not explain this sharp transition. Geol. Res. Div.,Scripps Inst. of Oceanogr., La Jolla, CA 92093, USA.

90:4007Storetvedt, K.M. et al., 1989. Magnetic structure and

evolution of the Island of Santa Maria, Azores.Phys, Earth planet. Interiors, 58(2-3):228-238.

A palaeomagnetic study reveals dominantly reversecharacteristic magnetizations. Sporadically occurringnormal polarity remanences are interpreted as an


overprinted component imposed by the island'sterminal volcanic phase. Combined with availableradiometric age estimates and local magnetic fieldinformation, an integrated interpretation indicatesthat the volcanic sequences covering the major partof the island Were laid down at around the Miocene/Pliocene boundary, immediately succeedingthe local Messinian sedimentary horizon. The question of a realistic lower age assessment for the older(pre-Messinian) volcanic complex remains undecided. Geofysisk Inst., Univ. of Bergen, N-5007 Bergen,Norway.

90:4008Vali, H. et al., 1989.Biogenic and lithogenic magnetic

minerals in Atlantic and Pacific deep sea sediments and their paleomagnetic significance. Geologische Rdsch., 78(3):753-764.

The carrier of the natural magnetization of deep-seasediments was characterized by mineralogical, electron microscopic, and rock magnetic investigations.The magnetic coarse fraction consists of lithogenicmagnetite and titanomagnetite; the fine fractionconsists of these plus biogenic magnetite. A graphical method is described which allows classificationand characterization of the magnetic fine fraction.Lehrstuhl fur Angewandte Mineral. und Geochem.,Tech. Univ. Munchen, Lichtenbergstr. 4, D-8046Garching, FRG.

90:4009Zhou, Moqing and Xu Li, 1989. Yellow Sea's

Holocene geomagnetic pole drifts and theirgeological significance. Mar. Geo!. Quat. Geol;9(2):35-40. (In Chinese, English abstract.)

Geomagnetic analysis of Core QC2 from the YellowSea reveals three polarity reversals. A sample fromthe deepest reversed section is dated by 14C at9910± 100 BP, the equivalent of the Gethornburgevent. Calculated sedimentation rates place the othertwo reversals at ages of 2600--3100 and 6000-MOOyrBP, approximately coincident with recognizedboundaries between palynological zones, thus suggesting a relationship between geomagnetism andclimate. lnst. of Mar. Geol., Ministry of Geo1. &Mineral Resour., Qingdao, People's Republic ofChina. (hbf)

D210. Heat flow

90:4010Speer, K.G., 1989. The Stommel and Arons model

and geothermal heating in the South Pacific.Earth planet. Sci. Letts, 95(3-4):359-366.

Joyce and Speer's (1987) model for the large-scaleinfluence of a geothermal heat source in an oceanbasin is applied to the South Pacific, taking intoaccount observed isopycnal depth variations andtracer distributions. These observations are usedwith the model to estimate the required geothermalheating and strength of the background Stommeland Arons flow. Both heating and background floware necessary in the model for agreement withobservations. IFREMER DERO/EO, B.P. 70, 29263Plouzane, France.

D240. Local or regional tectonics

90:4011Charvis, Philippe and Bernard Pelletier, 1989. The

northern New Hebrides back-arc troughs: historyand relation with the North Fiji Basin. Tectonophysics, 170(3-4):259-277.

A detailed bathymetric and magnetic survey over thenorthern back-arc troughs is used to propose a newmodel for their origin. Geometrical and structuralrelationships between the back-arc troughs and theHazel Holme fracture zone suggest that both theseextensional features are recent, still active, and resultfrom NE-SW extensional tectonics. Because othertectonic features throughout the basin are related tothe same stress field, it is inferred that NE-SWextension could be a large-scale deformation affecting the North Fiji Basin. These recent extensional processes could result from a major reorganization in the spreading process of the North FijiBasin and might be as young as 0.6-0.7 Ma,ORSTOM, Lab. de Geodynam. sous-mar., BP48,06230 Villefranche-sur-mer, France.

90:4012Hill, M.L., 1990.Transverse ranges and neotectonics

of southern California. Geology, geol. Soc. Am.,18(1):23-25. 14067E. Summit Dr., Whittier, CA90602, USA.

90:4013Hinz, K. et aI., 1989. Thrust tectonics along the

northwestern continental margin of Sabah/Borneo. Geologische Rdsch., 78(3):705-730.

Widely accepted plate tectonic models suggest thatan inactive subduction zone lies along the northwestcontinental margin of Sabah. In contrast, reflectionseismic data show an autochthonous continentalterrane comprising an Oligocene to Early Miocenecarbonate platform being progressively overthrust byan allochthonous rock complex. Progressive compression resulted in the development of four struc-

OLR (1990)37 (7) D. SubmarineGeologyand Geophysics 623

tural zones: imbricated thrust sheets; two thrustsheet systems one on top of the other ; a complexzone with multiphase deformation ; and piercementridges. Bundesanstalt fur Geowiss. und Robstoffe,Stilleweg 2, D-3000 Hannover 51, FRG.

90:4014Honza, Eiichi and J.-M. Auzende (and the Kaiyo 88

shipboard party), 1989. Geology of the riftsystem in the North Fiji Basin: results ofJapan-France cooperative research on boardKaiyo 88. Mer, Tokyo, 27(1-2):53-61. (In Japanese, English abstract.)

An initial report on geological observations madeduring a 1988cruise in the North Fiji Basin providesa description of the multiple rift systems within thebasin. Magnetic anomalies indicate that the centralN-S rift system, still in its initial stage, is at least 3m.y. old. An older northern rift, where hydrothermalactivity was observed, is in a later stage of development. (hbf)

90:4015Levchenko,O.V., 1989.Tectonic aspects of intraplate

seismicity in the northeastern Indian Ocean.Tectonophysics, 170(1-2): 125-139.

During the Late Cenozoic the northeastern IndianOcean region has been characterized by tectonicactivity that is unusual for a mid-plate setting andmore typical of plate boundaries. I t is suggested thatthe intraplate deformation in this region is episodic.A previous pulse of deformation occurred in theLate Miocene and modern tectonic activity, in thefonn of high seismicity, is related to a new pulse ofintraplate deformation. Seismic data analysis suggests a near-latitudinal equatorial seismic zone,comprising the northern Nin etyeast Ridge andnorthern central Indian and Cocos basins. Southward migration of the Himalaya subduction zonemay cause this high intraplate seismicity, and theepisodic intraplate deformation in this region mayherald a subduction zone along the southern marginof the Indian subcontinent. P.P. Shirshov Inst. ofOceanol., Moscow 117218, USSR.

90:4016Mackie, D.J. et al., 1989. The Queen Charlotte

Islands refraction project. Part II. Structuralmodel for transition from Pacific Plate to NorthAmerican Plate . Can. J. Earth Sci; 26(9):17131725.

The ocean-eontinental boundary west of the QueenCharlotte Islands is marked by the active QueenCharlotte Fault Zone . A 330-km offshore-onshoreseismic refraction profile was recorded to investigate

the structure of the fault zone and associatedocean-eontinental boundary and the lithosphericstructure bene ath the islands and Hecate Strait. Thederived velocity structure reveals some well-constrained features, but the data could not unambiguously define the mode of deformation. Two different tectonic models for the transition are discussed. In the most plausible model, oblique subduction is the principal characteristic; in the other,oceanic lithosphere is juxtaposed against continentallithosphere across a narrow boundary zone whereonly transcurrent motion occurs. Explor. Dept., ShellCanada Ltd ., P.O. Box 100, Calgary , AB T2P 2H5,Canada.

90:4017Martin, Laure and Jean Mascle, 1989. Structure and

recent evolution of the Aegean Sea: the CretanSea. C. r, Acad. Sci; Paris, (Ser, II)309(20):2061-2067. (In French, English summary.)

Seismic reflection data analysis reveals the shallowstructure of the southern Aegean Sea. Three mainstructural domains cut by a pattern of similarlytrending normal faults are recognized; however, thedominance of the individual fault system varies withthe area. The central Cretan Sea appears to resu ltfrom the interaction of two recent extensionssuperimposed on previous normal structures thatwere initiated at the beginning of Hellenic subduction. Lab. de Geodynam. sous-marine, B.P. 48,06230 Villefranche sur Mer, France.

90:4018May,D.J., 1989. Late Cretaceous intra-arc thrusting

in southern California. Tectonics, 8(6): 1159-1173.Dept. of Geol., Victoria Univ ., Wellington, NewZealand.

90:4019Schlich, Roland et at, 1989. Preliminary results of

Marion-Dufresne 61cruise on the Central IndianRidge between 21"8 and 25°3O'S. C. r. Acad.sa; Paris, (Ser. 11)309(18):1765-1772. (InFrench, English summary.)

The limits of the Rodriguez Triple Junction on theIndian-Australian Plate can be traced for a distanceof 230 km, Geophysical data over this area favor theunstable ridge- ridge- fracture zone proposed fortriple junction evolution between 5.9 Ma and thepresent ; however, between 7.2 and 5.9 Ma, theevolution of the triple junction followed a stableridge-ridge-ridge model. Location of the fracturezones and identification of magnetic linea tionsassociated with the Central Indian Ridge south of21'S suggest a new structural model. lnst. de Phys.


du Globe, Lab. de Geophys, Mar ., 5 rue ReneDescartes, 67084 Strasbourg Cedex, France.

90:4020TuIloch, A.J. and D.L. Kimbrough, 1989. The

Paparoa metamorphic core complex, New Zealand: Cretaceous extension associated with fragmentation of the Pacific margin of Gondwana.Tectonics, 8(6):1217-1234. New Zealand Geol.Survey, Lower Hutt, New Zealand.

90:4021Williamson, P.E. et al., 1990. Two-stage Early

Cretaceous rifting of the Otway Basin margin ofsoutheastern Australia: implications for rifting ofthe Australian southern margin. Geology, geol.Soc. Am., 18(1):75-78.

Analysis of a data base consisting of 3700 km ofmultichannel seismic reflection data and 12,000 kmof petroleum industry seismic data, integrated withwell data, indicates that rifting between the OtwayBasin off southeastern Australia and Antarcticaoccurred in two stages. Between 140 Ma and -110Ma, EW and ENE rift faults developed withinbasement. Then at 95 Ma, a set of ESE and SE faultsdeveloped over a less extensive area just prior to theonset of seafloor spreading. First stage trendspersisted during the second stage. Australian Bur. ofMineral Resour., P.O. Box 378, Canberra, ACT2601, Australia. (hbf)

90:4022Yoshioka, Shoichi and Manabu Hashimoto, 1989. A

quantitative interpretation on possible correlations between intraplate seismic activity andiuterplate great earthquakes along the NankaiTrough. Phys. Earth planet . Interiors, 58(23):173-191.

To investigate the possible relationship between the1944Tonankai earthquake along the Nankai Troughand the 1946 Nankaido earthquakes which occurredadjacent to the source region of the Tonankai event,calculated stress changes due to the Tonankaiearthquake were obtained using a 3-D finite elementmethod and then compared with post-seismic activity. Agreement between the two appears quite goodat a depth of ~ 10 km, indicating that E-W stressrelease associated with the Tonankai event may havereduced seismic activity inland. The calculatedresults show that post-seismic shear stress increasedand normal stress decreased near the hypocenterarea of the Nankaido earthquakes, while shear stressdecreased and normal stress increased in the surrounding area on the fault, facilitating rupture forthe Nankaido earthquake. This triggering mechanism may explain the pattern of historical great

interplate earthquakes along the Nankai Trough.Disaster Prevention Res. Inst., Kyoto Univ., Uji,Kyoto 611, Japan.

D250. Plate and global tectonics

90:4023Bott, M.H.P., G.D. Waghorn and A. Whittaker,

1989. Plate boundary forces at subduction zonesand trencb-arc compression. Tectonophysics,170(1-2): 1-15.

Viscoelastic finite element modelling has been usedto study stress in overriding and subducting platesmeeting at a subduction zone. It is demonstratedthat substantial horizontal deviatoric compressivestress occurs in the trench-arc region as a result ofdownpull 01 the dense slab and the associatedsurface dep~~ssion. The lack of significant shearingstress along an unlocked subduction fault in thepresence of this compressive stress gives rise to slabpull and trench suction plate boundary forces. Whenthe slab dips beneath the arc-backarc region ,horizontal deviatoric compression can occur in thisregion contemporaneous with plate in terior tensionproduced by trench suction. Successive locking andunlocking of the subduction fault may give rise tolarge variations of stress in plate interiors. Dept. ofGee!' Sci, Univ. of Durham, South Rd., DurhamDHI 3LE, UK.

90:4024Gradstein, Felix, John Ludden (co-chief scientists),

A.C. Adamson (ODP staff scientist) and OceanDrilling Program (Leg 122/123 shipboard scientific party), 1989. Triassic to Cenozoic evolution of the NW Australian continental marginalld the birth of the Indian Ocean (preliminaryresults of ODP legs 122 and 123). GeologischeRdsch; 78(3):1189-1210.

Eight sites were drilled in the Exmouth Plateau andadjacent abyssal plains; sites 759-761 and 764studied the Triassic-Cenozoic evolution of WombatPlateau; Site 765 on the Argo Abyssal Plainpenetrated almost I kID of Cretaceous-Cenozoicsediments and 270 m of oldest Indian Ocean crust ;sites 762 and 763 studied the southern centralExmouth Plateau; and Site 766 was drilled intointrusive volcanics under the Gascoyne AbyssalPlain. The major discoveries led to a better understanding of early rift history, rift-drift trans itionprocesses, the age and paleoenvironment of theoldest part of the Indian Ocean, juvenile and matureocean stages, the geochemical nature of old oceaniccrust, and the Mesozoic stratigraphy, age and causesof major sea level fluctuations.

OLR(1990)37 (7) D. Submarine Geology a nd Geophysics 625

D280. Volcanism, magmatism

90:4025Acton, G.D. and RG. Gordon, 1989. Limits on the

age of the Deccan Traps of India from paleomagnetic and plate reconstruction data and theirnncertainties. J. geophys. Res; 94(BI2):17,71317,720.

Revised limits on the age of the Deccan Traps areprovided by recent improvements to reconstructionsof India relative to surrounding plates since LateCretaceous time, realistic estimates of the uncertainties in the plate reconstructions, and recentpaleomagnetic data from the Deccan Traps andfrom North America. We place limits on the age ofthe Deccan Traps of 62-72 Ma, consistent with agesobtained independently from radiometric dating andpaleontology and with the hypothesis that theDeccan Traps were extruded rapidly during reversedpolarity chron 29r, which contains the CretaceousTertiary boundary. Dept. of Geo!' ScL, Northwestern Univ., Evanston , IL 60208, USA.

90:4026Allan, J.F. et al., 1989. Petrology of lavas from the

Lamont seamount chain and adjacent East PacificRise, looN. J. Petrology, 30(5):1245-1298.

The results of petrologic and geochemical studies oflava samples, retrieved by submersible and dredgings from the SE-NW trending, 50-km-long Lamontseamount chain, constrain the conditions and processes of melt extraction at spreading centers. Lavasfrom the chain are MgO-rich and contain lowabundances of incompatible elements, relative tothose of the adjacent EPR ; included are some of themost primitive lavas ever found in the easternPacific. Their mineralogy and petrology are consistent with heterogeneous mantle sources, variablydepleted in LREE and other incomp atibles, butotherwise are similar to EPR sources. ODP, TexasA&M Univ., College Station, TX 77843, USA. (hbf)

90:4027Batiza, Rodey, T.L. Smith and Yaoling Niu, 1989.

Geological and petrologic evolution of seamountsnear the EPR lEast Pacific Rise) based onsubmersible and camera study. Mar. geophys.Res; 11(3):169-236.

Seamount 5, closest to the EPR, is the youngest (1.0Ma) seamount and may still be active. Its summit iscovered by fresh lavas, recent fault s and hydrothermal deposits. Seamount D is on crust 1.55 Maand is inactive; like seamount 5, it has a breachedcaldera and is composed exclusively of N-MORB.Seamounts 6 and 7 have bumpy, flattish summits

composed of transitional and alkalic lavas probablyrepresenting caldera fillings and caps overlying anedifice composed of N-MORB. Evolution fromN-MORB-only cratered edifices to the alkalic stagedoes not occur on all near-EPR seamounts and maybe favored by location on structures with relativemotion-parallel orientation. Hawaii lnst. of Geophys., 2525 Correa Rd ., Univ. of Hawaii, H onolulu,HI 96822, USA.

90:4028Bottinga, Y. and M. Javoy, 1989. MORB degassing:

evolution of CO2, Earth planet. Sci. Letts,95(3-4):215-225.

The processes associated with the generation ofMORB in the upper mantIe produce a basaltic liquidwhich is saturated with CO2, During the migration ofthis liquid to a magma chamber just below the ridgecrest, nucleation of carbon dioxide bubbles takesplace. In the magma chamber MORB loses many ofthese primary bubbl es while it degasses. A secondgeneration of bubbles is nucleated during eruption.Our model explains the presence of relatively largeprimary bubbles rich in CO2 with a 13C/ I2C ratiocomparable to that of diamonds or carbonatites. Thesmaller secondary bubbles contain I2C-enriched CO2not greatly different in isotopic composition fromthe carbon remaining in solution when MORB isemplaced on the ocean floor . Contamination carbon,always present , tends to be even more enriched inllC. Inst. de Phys. du Globe, 4 place Jussieu, 75252Paris Cedex 05, France.

90:4029Chen, J.-C . and Yuzo Kato, 1989. Geochemistry of

volcanicrocks from the Ryukyu Islands comparedwith andesitic rocks from northern Taiwan. Actaoceanogr, taiwan ; 22:116-128.

Chemical analyses of Pliocene and Holocene volcanic rocks from Isbigaki-jima, Aguni-jima, Kumejima, and the Okinawa Trough provide a basis forcomparison of the rocks from the two regions. Majorand trace element chemistry and REE data suggestthat the Ryukyu andesites and dacites have beenderived through fractional crystallization of a parenta l basaltic magma, possibly contaminated by theaddition of continental crust. lnst. of Oceanogr.,Natl. Taiwan Univ., Taipei , Taiwan. (hbf)

90:4030Davidson , J .P. and R.S. Harmon, 1989. Oxygen

isotope constraints on the petrogenesis of volcanicarc magmas from Martinique, Lesser Antilles.Earth planet. Sci. Letts, 95(3-4):255-270.

Volcanic rocks from Martinique are highl y diverse


isotopically. O-isotope ratios are compositionallydependent: correlations between 8180 and radiogenic isotope ratios and indices of fractionationshow that modification of isotopic compositionsoccurred during magmatic differentiation ratherthan at source. A two-stage model is proposed forthe origin and differentiation of magmas on Martinique. Primary basaltic melts, similar in composition to primitive island-arc magmas elsewhere, aregenerated from subduction-modified asthenosphericmantle, ascend into the arc crust, and differentiate .Crystal fractionation is accompanied by contaminat ion with isotopically distinct crust, including aterrigenous sediment component. Thus, subductionzone processes at the Lesser Antilles and other islandarcs are similar, involving a small, but isotopicallysignificant, volumetric contribution from subductedsediment. Dept. of Earth and Space Sci., Univ. ofCalifornia, Los Angeles, CA 90024, USA.

90:4031Davies, H.L. et al., 1989. Basalt basement from the

Kerguelen Plateau and the trail of a Dupal plume.Contr. Miner. Petrology, 103(4):457-469.

The first samples of volcanic basement recoveredfrom the Kerguelen Plateau are Lower Cretaceoustransitional tholeiites. Isotope and incompatibleelement abundance ratios for these rocks are similarto OIB from the Southern Hemisphere Dupalanomaly region, and geochemical, geological andgeophysical data are consistent with volcanic activityassociated with a mantle plume. A plate reconstruction suggests that the Kerguelen Plateau formedabove a mantle plume in the interval 118-95 Ma,during the opening of the Indian Ocean. This plumewas the source of other plateaus and ridges of theeastern Indian Ocean and possibly the Bunburybasalt of southwestern Australia, and is now beneathHeard Island. Bur. of Mineral Resour., BPO Box378, Canberra ACT 2601, Australia.

90:4032Dixon, T.H., E.R. Ivins and B.J. Franklin, 1989.

Topographic and volcanic asymmetry around theRed Sea: constraints on rift models. Tectonics,8(6):1193-1216.

The Red Sea Rift is asymmetric, with the locus ofuplift and Tertiary volcanism east of the present riftaxis. A model is proposed which involves interactionof upwelling asthenosphere during early rifting witha nearby crustal weak zone that controls riftlocation. The location of the weak zone andsubsequent rift will generally not coincide with thelocus of upwelling, leading to several asymmetric riftfeatures . Implications for this model of rift evolutionare discussed . Div. of Earth and Planetary Sci., Jet

Propulsion Lab., California Inst. of Tech., Pasadena,CA, USA.

90:4033Foulger, G.R. and D.R. Toomey, 1989. Structure

and evolution of tbe Hengill-Grensdalur volcaniccomplex, Iceland: geology, geopbysics, and seismic tomography. J. geophys, Res., 94(B12):17,511-17,522.

Recent research indicates the presence of threevolcanic systems in the Hengill-Grensdalur area andprogressive westerly migration of the accretionaryplate boundary. A tomographic study of the upper 5krn of crust using local earthquakes, imaged threehigh-velocity bodies, several tens of cubic km involume. One under the Grensdalur Volcano and asecond under the Olkelduhals area are interpreted assolidified magma reservoirs of their volcanic systemsand heat sources of the overlying geothermal areas.The third body under the extinct Husmuli basaltshield may be the frozen magma conduit that fed thesurface eruption . A smaller low velocity bodybeneath the active Hengill central volcano maycontain partial melt and represent the heat sourcefueling the Hengill field. Dept. of Geol. Sci., Univ. ofDurham, South Rd., Durham DRI 3LE, UK.

90:4034Goldstein, S.J., M.T. Murrell and D.R. Janecky,

1989. Th and U isotopic systematics of basaltsfrom the Juan de Fuca and Gorda ridges by massspectrometry. Earth planet. Sci. Letts, 96{12): 134-146.

A mass spectrometric technique for measurement of23OTb/ 232Th ratios in young volcanic rocks, that canmeasure Th ratios with an accuracy of 0.5-1.0%,represents an improvement of at least a factor of5-10 in sample size and precision over conventionalalpha spectrometry methods. Measured excesses of230Tb activity relative to 238U activity for axialsamples from the Juan de Fuca and Gorda ridges are13-15%, but range up to 40% in one sample. It isinferred that primary magmatic processes are thesource of the measured excesses and that Th is moreincompatible than U during partial melting ofMORB sources. Isotope Geochem., Group INC-7,Los Alamos Natl. Lab., Los Alamos, NM 87545,USA.

90:4035Hegner, E. and M. Tatsumoto, 1989. Pb, Sr, and Nd

isotopes in seamount basalts from the Juan deFuca Ridge and Kodiak-Bowle seamount chain,northeast Pacific. J. geophys. Res., 94(BI2):17,839·17,846.

OLR (1990) 37 (7) O. Submarine Geology and Geophysics 627

Nd and Sr isotopic compositions for 28 basalts from10 seamounts plot in the envelope for Juan deFuca-Gorda ridge basalts with tholeiitic basaltsshowing more depleted sources and a better negativecorrelation than transitional to alkalic basalts. Pbisotopic ratios in tholeiitic and alkalic basaltsoverlap and display a trend toward more radiogenicPb in alkalic basalts. The isotopic data for hotspotand non-hotspot basalts are indistinguishable andcorrelate broadly with rock composition, implyingthat they are controlled by partial melting. The dataindicate absence of a chemically distinct plumecomponent in the linear seamount chains andstrongly suggest an origin from MORB-like eastPacific mantle. Geol. Survey of Canada, 601 BoothSt., Ottawa KIA OE8, Canada.

90:4036Hekinian, Roger, Geoffrey Thompson and Daniel

Bideau, 1989. Axial and off-axial heterogeneityofbasaltic rocks from the East Pacific Rise at12"3S'N-lZOSl'N and llo26'N-llo30'N. J.geophys. Res., 94(BI2):17,437-17,463.

Surface ship operations and 40 submersible diveshave provided observations and rock samples fromtwo segments of the EPR and four adjacent seamounts. There is no correlation between lava flowmorphology, geological settings, and compositions.Simplecrystal fractionation accounts for some of thecompositional range. However, on the basis of theirincompatible elements, the basalts can be dividedinto three groups which occur within limited portions of the axial graben and its limbs in areas <10km in length and <3-4 km in width. Two mantlesources are distinguishable, and a composite lherzolitic mantle with minerals having a variablebehavior under partial melting is suggested.IFREMER, Ctr. Oceanol. de Bretagne, Dept.Geosci. Mar., BP 70, 29273 Plouzane, France.

90:4037Hildebrand, J.A. et al., 1989. Seismic tomographyof

Jasper Seamount. Geophys. Res. Letts, 16(12):1355-1358.

A vertical section of the interior structure of JasperSeamount was modeled using a spectral tomographicinversion of P wave travel times. Average compressional velocities within the seamount are similarto those found within Kilauea and are consistentlyslower than velocities at equivalent depths in typicaloceanic crust, suggesting a high average porosity. Ahigh velocity zone within the northwest flank of theseamount may result from dikes associated with aradial rift or from a shallow solidified magmareservoir. A low velocity summit may result from

shallow, explosive eruptions. Scripps Inst. ofOceanogr., La Jolla, CA 92093, USA.

90:4038Hilton, D.R. and H. Craig, 1989. A helium isotope

transect along the Indonesian Archipelago. Nature, Land; 342(6252):906-908.

In eleven of twelve circum-Pacific arcs, MORB-like3He/4He ratios show dominantly primordial heliumfrom the mantle wedge above the sinking slab, ratherthan radiogenic helium from subducting crust. Onlyin the Banda Arc have significantly lower ratios beenobserved, corresponding to as much as 80% radiogenic helium. We now report 3He/4He measurements along a 1800-km section of the Sunda Arcshowing MORB-like ratios from western Java to asurprisingly sharp transition zone centered onLomblen Island, where the low ratios of the BandaArc begin. Our results demonstrate a remarkablelinkage of helium isotope variations with tectonicprocesses not readily discernible with trace elementsor other isotopes. Free Univ . of Berlin, PB 24, FRGeochem., Boltzmannstr. 18-20, 1000 Berlin 33,FRG.

90:4039Melosh, H,J., 1990. Mechanical basis for low-angle

normal faulting in the Basin and Range province.Nature, Lond; 343(6256):331-335.

Low-angle normal faults seem to violate the criterionthat relates fault dip to stress orientation. To explainsuch faults one must postulate a 450 rotation ofprincipal stress directions at mid-crustal depths ,which is difficult to understand on the basis ofprevious elastic crust models. Such a stress rotationis shown to be a natural consequence of a lowviscosity lower crust. Dept. of Geosci., Univ. ofArizona, Tucson, AZ 85721, USA.

90:4040Mouginis-Mark, P.J. et aI., 1989. Remote sensing of

volcanos and volcanic terrains, Eos, 70(52): 1567,1571, 1575,

Much progress has been made in the use of bothsatellite and aircraft remote sensing techniques tocollect data on the dynamics of volcanic eruptionsand on the interactions between volcanos and theatmosphere and ecosphere. Measurements made inthe ultraviolet provide estimates of the mass of S02released; the hemispheric dispersal of eruptionplumes can be tracked via weather satellites ; infrared images can be processed to produce temperaturemaps of lava flows and volcanic craters; andvoLumes of volcanic flows and cones can bemeasured via radar interferometry. The global

628 D. Submarine Geology and Geophysics OLR (1990)37 (7)

perspective provided by satellite remote sensingtechniques will become another valuable tool in theanalysis of volcanos and their deposits. Hawaii lnst.of Geophys., Univ. of Hawaii, Honolulu, HI , USA.

90:4041Staudacher, Th. et al., 1989. Noble gases in basalt

glasses from a Mid-Atlantic Ridge topographichigh at 14"N: geodynamic consequences. Earthplanet. Sci. Letts, 96(1-2): 119-133.

The highest 4°Arj36Ar ratio ever observed for aMORB glass was found in a sample from a smallsegment of the Mid-Atlantic Ridge , correlated withhigh 129Xe/1JOXe ratios and the highest noble gasconcentrations in a 'popping rock.' This sampleprobably represents the elemental noble gas ratios inthe mantle. Based on this ratio, the 4He concentration in the mantle source of MORB is 1.5 X 10-5

cnr' STP g-I. High 4He/JHe ratios in two samplesfrom the ridge summit indicate a U, Th-richcomponent in the mantle source, possibly oldsubducted oceanic crust or sediments, which couldoriginate in the 'mesosphere' boundary layer. Lab.de Geochim. et Cosmochirn., Inst. de Phys. du Globede Paris, 4 place Jussieu, 75252 Paris Cedex OS,France.

90:4642Stothers, R.B. , 1989. Volcanic eruptions and solar

activity. J. geophys. Res., 94(B12):17,371-17,381.

The historical record of large volcanic eruptionsfrom 1500 to 1980 is subjected to detailed time seriesanalysis. Two weak , but probably statistically significant, periodicities of -11 and -80 years aredetected. Both appear to correlate with well-knowncycles of solar activity; the phasing is such that thefrequency of volcanic eruptions increases (decreases)slightly around the times of solar minimum (maximum). Mechanisms to explain the Sun/Volcanolink probably involve induced changes in the basicstate of the atmosphere. Solar flares are believed tocause changes in atmospheric circulation patternsthat abruptly alter the Earth's spin. The resulting joltprobably triggers small earthquakes which maytemporarily relieve some of the stress in volcanicmagma chambers, thereby weakening, postponing,or even aborting imminent large eruptions. GoddardInst, for Space Studies, 2880 Broadway, New York ,NY 10025, USA.

90:4043Toutain, J.-P. and Georges Meyer, 1989. Iridium

bearing sublimates at a bot-spot volcano (Piton dela Fournaise, Indian Ocean). Geophys. Res. Letts,16(2):1391-1394.

Sublimates and incrustations derived upon thecooling of volcanic gases have been collected onvario us sites. Analysed for Ir and other volatileelements (Se, As, Cu, Au, Ag, Pb, Tl), only Piton dela Fournaise among the investigated volcanoes isfound to release detectable amounts of iridium ; itsgaseous transport as a volatile fluoride compound isconfirmed. Iridium seems to be preferentially reoleased by hot-spot type volcanoes, and its detectionin Piton de la Fournaise sublimates provides apositive argument in favour of a volcanic hypothesisto explain KIT boundary events. IPG Paris, Observ,Volcano\. du Piton de la Fournaise, 97418 La Plainedes Cafres, France.

90:4044Vance, D., J.O.H. Stone and R.K. O'Nions, 1989.

He, Sr and Nd isotopes in xenoliths from Hawaiiand other oceanic islands. Earth planet. Sci. Letts,96(1-2): 147-160.

Isotopic analyses on He, Sr, and Nd are reported forultramafic and gabbroic xenoliths from the Hawaiian Islands , Canary Islands, Kerguelen, Gough, andMadeira. He compositions in samples of variedpetrologic types from Hawaii show a remarkablynarrow range and are indistinguishable from therange of He ratios in MORB. In contrast, Sr and Ndisotopic compositions show a significant range.Samples from the other islands, considered as agroup, show similar trends. The relationship betweenHe and Sr-Nd isotopes of ocean island xenoliths isstrikingly similar to that of continental ultramaficxenoliths. These systematics suggest metasomaticintroduction of lithophile and volatile elements intothe lithosphere beneath ocean islands, overprintingdepleted mantle isotopic characteristics. Div. ofGeo\. and Planet. Sci., California Inst. of Tech.,Pasadena, CA 91125, USA.

D290. Crust, mantle, core

90:4045Allegre, C.J. and Eric Lewin, 1989. Chemical

structure and history of tbe Earth: evidence fromglobal non-Unear inversion of isotopic data in athree-box model. Earth planet. Sci. Letts, 96(12):61-88.

We combine previous information from Sr-Nd andthree Pb isotopic couples and add the Hf and Osisotopic couples. Budget equation inversion and themodel ages-crustal age histogram relationships formthe basis of a systematics of the behaviour ofchemical elements through the phenomenon of crustformation, and permits us to calculate a parameter


accounting for the 'large scale' behaviour of eachchemical element that we call the sialic affinity. Theuse of a Cl chondrite chemical concentration setenables us to bound the concentration factor of thebulk silicate Earth to the depletion factor of themantle. Lab. de Geochim. et Cosmochim., Inst. dePhys. du Globe, 4 Place Jussieu, 75252 Paris Cedex06, France.

90:4046Azbel, LYa. and LN. Tolstikhin, 1990. Geodynamics,

magmatism, and degassing of the Earth. Geochim.cosmochim. Acta, 54(1):139-154.

Terrestrial degassing processes are identified on localand global scales and combined in a single model ofevolution of the upper mantle, crust and atmosphere.The model envisages early intensive convection andfractionation in the upper mantle resulting in sharpdegassing; later, slow convection in this reservoiraccompanied by partial melting of silicate matter inrift and subduction zones; uplift of melts into thecrust and their degassing; early formation andsubsequent recycling of continental crust and itsdegassing due to magmatism and metamorphism;and accumulation of gases, except for He, in theatmosphere. Geol. Inst., Kola ScL Ctr., Acad. of Sci.,Apatity 184200, USSR.

90:4047Boyd, F.R., 1989. Compositional distinction between

oceanic and cratonic lithosphere. Earth planet.Sci. Letts, 96(1-2):15-26.

Oceanic residues represented by abyssal peridotites,ophiolite tectonites, and alpine peridotites arecharacteristically olivine-rich with mg numbers of90.5-91.5. In contrast, peridotite xenoliths withequlibration temperatures <lIQO-I2oo°C from theArchean Kaapvaal craton are more enstatite-richwith mg numbers of 91.5-93.5. Structures andcompositional relations of other Archean cratons aresimilar to the Kaapvaal. Oceanic residues arebelieved to be of relatively shallow origin. Mg-richperidotite xenoliths from mafic volcanics erupted incontinental areas marginal to Archean cratons havecompositions that fit the oceanic trend, but Archeancratonic peridotite history differs from those formingoceanic lithosphere, and it is conjectured that theyare high-pressure residues of komatiite formation.Geophys. Lab., Carnegie Inst. of Washington, 2801Upton St. N.W., Washington, DC 20008, USA.

90:4048Briais, Anne, Paul Tapponnier and Guy Pautot,

1989. Constraints of Sea Beam data on crustalfabrics and seafloor spreading in the South ChinaSea. Earth planet. Sci. Letts, 95(3-4):307-320.

Two cruises to the South China Sea provided seismicreflection, magnetic, and gravity profiles, and SeaBeam data that exhibit two major structuraltrends-scarps striking -N50"E, interpreted asnormal faults, and scarps striking ,.,..,NI40oE, interpreted as fracture zones-which imply a NW-SEspreading direction up to 100 km north and south ofthe inferred spreading axis. Dense Sea Beam coverage of a 1" square area northwest of the Scarborough seamounts shows that emplacement of theseamounts was initially controlled by faulting alongN500E and Nl400E lines. Progressive right-lateraloffsets of the ridge across closely spaced discontinuities may account for the nearly E-W averagetrend of some of the magnetic anomalies and of theScarborough seamount chain. Inst. de Phys. duGlobe de Paris, 4, Place Jussieu, 75252 Paris Cedex05, France.

90:4049Calmant, S., J. Francheteau and A. Cazenave, 1990.

Elastic layer thickening with age of the oceaniclithosphere: a tool for prediction of the age ofvolcanoes or oceanic crust. Geophys, J. int.,1OO( 1):59-67.

To first order, the estimated thickness of the elasticpart of the oceanic lithosphere increases linearlywith the square root of the age of the lithosphere atthe time of loading. To quantify this relationship inthe case of volcanic loading, a synthesis of estimatesreported both in this paper and in previous studies isconducted. Excluding the anomalously low estimatesfrom the south-central Pacific, the values are veryconsistent for the three main oceans and follow anempirical relationship which is used to predict theage of volcanoes when the age of the crust is knownand to predict the age of the crust when the age ofthe volcanoes is known. The age estimates are ingood agreement with the structural setting. CRGS,CNES, 19 avo E. Belin, 31055 Toulouse cedex,France.

90:4050Coltrin, George et al., 1989. Seismic reflection

imaging problems resulting from a rough surfaceat the top of the accretionary prism at convergentmargins. J. geophys. Res., 94(B12):17,485·17,496.BP Exploration (Alaska) Inc., Develop. Geosci.,P.O. Box 196193, Anchorage, AK 99519, USA.

90:4051Cox, K.G., 1989. The role of mantle plumes in the

development of continental drainage patterns.Nature, Lond., 342(6252):873-877.

The geomorphology of three continental flood-basaltprovinces supports a recent model for the generation

630 D. Submarine Geology and Geophy sics OLR (1990)37 (7)

of such provinces by melting of hot mantle plumes.Characteristic drainage patterns indicating topographic doming associated with plume activity arestill preserved after up to 200 Myr. Crustal thickening by magmatic underplating is the most likelycause of the persistence of such features. Dept. ofEarth Sci., Parks Rd., Oxford OXI 3PR, UK.

90:4052Dosso, S.E. and D.W. Oldenburg, 1989. Linear and

non-linear appraisal [of seismic model features Iusing extremal models of bounded variation.Geophys. J. tnt; 99(3):483-495. Dept. of Geophys. and Astron., Univ. of British Columbia,129-2219 Main Mall, Vancouver, BC Y6T lW5,Canada.

90:4053Gliko, A.O. and J.-C. Mareschal, 1989. Non-linear

asymptotic solution to Stefan-like problems andthe validity of the linear approximation Ito tbedetermination of phase-change boundary movemeot in the earth]. Geophys.J, int; 99(3):801-809.Inst. of Phys. of the Earth, Acad. of Sci.,Moscow, USSR.

90:4054Goodman, Dean, L.D. Bibee and L.M . Donnan,

1989. Crustal seisnuc structure beneath the westPhilippine Sea, 17°_18° North. Mar. geophys.Res; 11(3):155-168.

Total crustal thicknesses in the eastern part of theocean basin approach only 3.5 km. Crustal thinningtoward the east is consistent with the Palau KyushuRidge being a remnant transform fault connectingthe Central Basin Ridge and the Kula Pacific Ridgein the past. The upper transitional crust layer hasstrong velocity gradients which gradually decreasewith depth; the lower crust is characterized by anearly constant velocity gradient. The western partof the basin has more typical thicknesses. Predictedwater depths for the West Philippine Basin, using anage-depth relation and corrected for an isostaticresponse, are still 300 meters shallower than observed depths. This implies that a deeper seatedanomaly is present beneath the West PhilippineBasin . RSMAS, Univ. of Miami, FL, USA.

90:4055Granet, M. and J. Trampert, 1989. Large-scale

P.velocity structures in the Euro-Mediterraneanarea. Geophys. J. int; 99(3):583-594.

The Simultaneous Iterative Reconstruction Technique (SIR1) is used to invert the data, while thedirect problem is formulated by using a sphericalblock partition of the model space and an analytical

ray trac ing so that the whole ray path lies in theinvestiga ted 3-D model box. A synthetic test showsthe reliability of the results for structures beneath thelithosphere, while for shallower parts of the modeland depths larger than 900 km, limited reliability isachieved . For the upper mantle, the model showsclear correlations with major known surface tectonicfea tures. At greater depths, the model shows slowvelocities around 600 km beneath the two mainHercyn ian massifs in Europe . lnst. de Phys. duGlobe , 5 rue Rene Descartes , 67084 StrasbourgCedex, France.

9():4056Hanes, H.-P. and H. Krummel, 1989. Combined

processing of seismic reflection and boreholemeasurements in the Moroccan Basin offshoreNW Africa at DSDP Site 416. GeologischeRdsch; 78(3):691-703.

The purpose of this paper is to show the potential ofreflection seismic data to support stratigraphicinterpretation. Computation of synthe tic seismograms using borehole data as input allowed us toassociate reflection horizons with geological boundaries. Reconnaissance surveys within ODP programspresent an excellent opportunity to use quantitativemodelling techniques to understand the origin of theseismic record in a specific region and examine theuse of seismic stratigraphy as an important tool inmarine geosciences. lnst. of Geophys., Ruhr Univ.,D-4630 Bochum, FRG.

90:4057Iidaka, Takashi, Megumi Mizoue and Kiyosh i

Suyehiro, 1989. Seismological evidence on velocity structure inside the subducting Pacific Plate.Phys. Earth planet. Interiors, 58(2-3):249-254.

A 3-D seismic tracing scheme was applied to resolvethe complex inside structure of the subducting plate.It was found that a model with a rapid increase inP-wave velocity in the upper few tens of kilometresthickness and a gradual decrease within the rest ofthe plate explains the observation better than modelswith velocity maxima at different locations . Earthquake Res. Inst., Univ. of Tokyo, Yayoi 1-/ -1,Bunkyo, Tokyo 113, Japan.

90:4058Jarvis, G.T. and IX. Mitrovica, 1989. On Nusselt

munbers and the relative resolution of plumes andboundary layers in mantle convection. Geophys. J.int ; 99(3):497-509.

The fact that vertical plumes and horizontal boundary layers have different cross-sectional dimensions


in idealized models of mantle convection is quantified and then exploited to provide a criterion forthe selection of an optimal ratio of horizonta l andvertical spatial increments in finite difference solutions to equations governing mantle convection. Theeffects of varying the ratio on the computed value ofthe Nusselt number is assessed by a suite of 21model solutions of Benard convection at the sameRayleigh number but with varying grid dimensions.In general, the Nusselt number is much less sensitiveto loss of horizontal resolut ion than vertical. Implications of the results Cor modeling convection in theEarth's mantle are discussed. Dept. of Earth andAtmos . Sci., York Univ., North York, ON M3J IP3,Canada.

90:4059Kebede, Fekadu and Ota Kulhanek, 1989. Source

parameters of [196) selected earthquakes on thecentral and western margin of Afar. Tectonophysics, 170(3-4):243-257.

For the earthquakes in the regions under study, thestress drop varies from 2 to 31 bar while the seismicmoment varies from 2 X 1024 to 154 X 1()24 dyn em,In general, low stress drop values are obtained,indicating the presence of softer material at ashallower depth. There is an increase in stress dropwith increase in moment magnitude. Energy estimates show that the mode of energy release isdifferent in the two regions, ind icating differenttectonic processes. Spreading rates indicate a lowspreading rate for Afar and neighbouring regionscompared to those of other regions of the world.Seismol. Dept., Uppsala Univ., Box 12019, S-750 12,Uppsala, Sweden.

90:4060Kesson, S.E. and A.E. Ringwood, 1989. Slab-mantle

interactions. 1. Sheared and refertilised garnetperidotite xenoliths-samples of Wadati-Benioffzones? Chern. Oeol., 78(2):83-96.

Most sheared, deformed garnet peridotite-faciesxenoliths found in kimberlites have been formedfrom initially depleted peridotite protoliths whichhave been modified in varying degree by theintroduction of Ti, Fe, Ca, Na, P, Zr, and Ycontained in silicate melts. It is proposed that theserocks acquired their high equilibration temperatures,chemical character, and highly deformed fabricsalong Wadati-Benioff zones in regions of activesubduction beneath cratons where slab-derived meltswere episodically injected into peridotite immediately overlying former oceanic crust; the hybridization occurs at this boundary. Local transient heatwould accoun t for the seemingly elevated equilibration temperatures recorded by these rocks. Res.

School of Earth Sci., Australian Natl, Univ., Canberra, ACT 2601, Australia.

90:4061Kesson, S.E. and A.E. Ringwood, 1989. Slab-mantle

interactions. 2. The formation of diamonds. Chern.Geol., 78(2):97-1I8.

A wide range of evidence indicates that the formation of most diamonds was closely associatedwith subduction of oceanic lithosphere into themantle. Syngenetic minerals included in diamondsshow that they crystallized in two distinct, spatiallyrelated lithologies-eclogite and refractory harzburgite/dunite. The P-T regimes of diamond crystallization support this interpretation, as does theplastic deformation record of diamond. Most diamonds appear to have crystallized in the presence ofa melt rather than a fluid phase. It is proposed thatthe formation of diamonds is another example ofslab-mantle interaction. Res. School of Earth ScL,Australian Nat!. Univ., Canberra, ACT 2601, Australia.

90:4062Matyska, Ctirad, 1989. Angular symmetries of bot

spot distributions. Earth planet. Sci. Letts, 95(34):334-340.

The symmetries in the distribution of hotspots areinvestigated by an analogy of the angular autocorrelation of scalar fields. It has been applied to twolists of hotspot locations, revealing the axes as wellas the angles of symmetries. The existence of angularsymmetries suggests that the hotspot distributionobservable on the Earth's surface is probablyinfluenced by symmetries of deep geodynamicprocesses. Dept. of Geophys, and Meteorol., CharlesUniv., V Holesovickach 2, 180 00 Prague 8, Czechoslovakia.

90:4063Oda, Hiroshi, Takeshi Tanaka and Kiyoshi Seya,

1990. Subducting oceanic crust on the PWUppineSea Plate in southwest Japan. Tectonophysics,172(1-2): 175-189.

In southwest Japan, it is widely accepted that thePhilippine Sea Plate (PHS) subducts beneath theEurasian Plate, and oceanic crust is expected todescend as part of the PHS Plate. Observations ofearthquakes at a single station in Chugoku districthave detected a distinct pair of later P and S phasesafter weak initial P and S phases. These later phaseswere observed only for quakes with particularsource-receiver geometries and could not be explained unless the subcrustal earthquakes take place

632 D. Submarine Geology and Geophysics OlR (1990) 37 (7)

within low-velocity oceanic crust overlying highvelocity oceanic plate. This suggests that the oceaniccrust subducts beneath the west Seto Inland Sea aspart of the PHS plate. Dept. of Earth Sci., OkayamaUniv., Okayama 700, Japan.

90:4064Pallister, J.S. et al., 1990. Use and abuse of crustal

accretion calculations (Arabian-Nubian shield],Geology, geol, Soc. Am; 18(]) :3S-39. USGS, M.S.903, Federal Ctr., Denver, CO 80225, USA.

90:4065Ricard, Yanick and Christoph Vigny, 1989. Mantle

dynamics witb induced plate tectonics. J. geophys.Res; 94(BI2):17,543-17,559.

Mantle circulation and plate tectonics can bedescribed by means of a poloidal field related tovertical mass flux and a toroidal field whichexpresses rotations within spherical shells. Surfacekinetic energy is equally distributed between the twofields . A new model which takes into account theexistence of rigid and independent plates is developed. This model explains the generation of toroidalflow and clearly demonstrates that surface platesstrongly affect the whole mantle dynamics. Dept. deGeophys., Ecole normale Superieure, 24 rueLhomond, 75231 Paris Cedex 05, France.

90:4066Richards, M.A. and R.W. Griffiths, 1989. Thermal

entrainment by deflected mantle plumes. Nature,Lond.; 342(6251):900-902.

As they rise through the mantle, thermal plumesentrain surrounding material by thermal conduction,and small plumes or narrow plume conduits mayconsist of only a small fraction of original sourcematerial. Here we present new experimental resultswhich show this effect dramatically for plumeconduits that are deflected horizontally by shearflow in the mantle beneath lithospheric plates.Thermally entrained material can become concentrated at the center of a plume (or surface hotspottrace) with original source material in the periphery.Also, the diapiric instability observed in chemicalplume conduits is suppressed by thermal entrainment. Varying degrees of geochemical enrichmentobserved at hotspots such as the Galapagos Islandsmay result from thermal entrainment, implying thatmantle plumes are driven by thermal (rather thancompositional) buoyancy. Dept. of Geo1. and Geophys., Univ, of California, Berkeley, CA 94720,USA.

90:4067Rydelek, PA and I.S. Sacks, 1990. Asthenospheric

viscosity and stress diffusion: a mechanism toexplain correlated earthquakes and surface deformations in NE Japau. Geophys, J. int; 100(1):39-58.

Examination of the distribution of intraplate (land)and interplate (sea, thrust zone only) earthquakessince 1600reveals a correlation between events, withland earthquakes preceding sea earthquakes by -36yr at an average distance of 200 km and an impliedaverage strain migration rate of 5.6 kID yr ', It issuggested that the land- events are the result ofbuckling of the land plate produced by the force ofthe underlying subducting slab and that sea eventsare the result of viscoelastic coupling of the plate tothe asthenosphere. The inferred strain rate providesan estimate of 7 X 1018 Pa s for asthenosphericviscosity, as compared with an estimate of I3 X 1018

Pa s, based on surface deformation determined bytriangulation surveys. Schiltach Observ., Heubach206, 7620 Wolfach, FRG. (hbf)

90:4068Sato, Haruo, 1989. Broadening of seismogram envel

opes in the randomly inhomogeneous lithospherebased on the parabolic approximation: southeastern Honshu, Japan. J. geophys. Res;94(B12):17,735-17,747. Nat1. Res. Ctr. for Disaster Prevention, Tennodai 3-], Tsukuba-shi,Ibaraki-ken 305, Japan.

90:4069Strelitz, R.A., 1989. Choosing the 'best' double couple

from a moment-tensor inversion. Geophys. J. int;99(3):811-815.

General moment-tensor solutions contain doublecouples, compensated linear vector dipoles (CLVDs)and isotropic sources. It is important to find the'best' double-couple solution that is consistent withthe original solution. It is proved that for a numberof reasonable measures of fit, the best double coupleis the one formed by removing a CLVD source witha magnitude of the intermediate non-zero eigenvalue. Mixtures of double couple and CLVDs mayresult from near-source changes in rigidity . Dept. ofGeo!., Duke Univ., Durham, NC 27706, USA.

90:4070Takei, Yasuko and Daisuke Suetsugu, 1989. A

high-velocity zone in tbe lower mantle under theJapan subduction zooe inferred from precisemeasurements of P·wave arrival times. J. Phys.Earth, 37(3):225-231.

OLR (1990)37 (7) D. Submarine Geology and Geophysics 633

Travel time data for nine magnitude >5.5 earthquakes in the Japan subduction zone, directly andprecisely read from World-Wide Standardized Seismograph Network records, are analyzed to determine whether the slab beneath the Japan subductionzone is descending into the lower mantle. The resultsof the study suggest the existence of a high-velocityzone beneath the 650-km discontinuity. The resultant travel time anomalies are also compared toanomalies obtained using International Seismological Centre data for these events. Dept. of Geophys.,Univ. of Tokyo, Japan.

90:4071Toomey, D.R. and G.R. Foulger, 1989. Tomographic

inversion of local earthquake data from theHengill-Grensdalur central volcano complex,Iceland. J. geophys. Res; 94(B12):17,497-17,51O.Dept. of Earth, Atrnos, and Planetary Sci.,Room 54-512, MIT, Cambridge, MA 02139,USA.

90:4072Tricart, Pierre et al., 1989. Morpbostructural analysis

in the Romanche Fracture Zone, 17 to 18°W:preliminary data from the Equamarge II cruise(1988). C. r. Acad. sa, Paris, (Ser. 1I)309(I8):1797-1802. (In French, English summary.)

An active portion of the Romanche Fracture Zonewas surveyed between 17° and 18°W in the equatorial Atlantic. The results of Seabeam mapping andseismic reflection surveys within the trench andadjacent transverse ridges emphasize the contrastbetween the apparent simplicity of the majormorphostructures and the complexity of the secondorder features. Lab. de Geo!., Fac. des Sci., 72017 LeMans, France.

90:4073U.S. Geological Survey Staff, (office of earth-

quakes, volcanoes and engineering), 1990. TheLorna Prieta, California, earthquake: an anticipated event. Science, 247(4940):286-293.

The first major earthquake on the San Andreas Faultsince 1906 fulfilled a long-term forecast for itsrupture in the southern Santa Cruz Mountains.Severe damage occurred at distances of up to 100kmfrom the epicenter in areas underlain by groundknown to be hazardous in strong earthquakes. TheLorna Prieta earthquake demonstrated that meaningful predictions can be made of potential damagepatterns and that, at least in well-studied areas,long-term forecasts can serve as a basis for action toreduce the threat major earthquakes pose to theUnited States. ©1990 by AAAS. Off. of Earthquakes,

Volcanoes, and Engng, USGS, Mail Stop 977, 345Middlefield Rd., Menlo Park, CA 94025, USA.

D330. Oil and gas

90:4074Chemova, T.G. and M.A. Levitan, 1989. Bituminous

substances in bottom sediments of the Namibiacontinental margin. Int. Geol. Rev; 31(9):958967.

Bottom sediments of the Namibian continentalmargin, where primary bioproductivity is extremelyhigh due to rapid shelf upwelling, were collectedduring four transects of the shelf, and analyzed todetermine their potential as a source for petroleum.The organic matter reaching the floor is producedmainly by diatoms and enriches the sediments withsapropelic-type material. The distribution of organiccarbon reflects the distribution of the main sedimenttypes (pelitic mud and various sands) and variessignificantly from shelf to slope. Petroleum sourcematerial characteristics of the bituminological fraction are similar to those of oil. Inst. of Oceanol.,Acad. of ScL, Moscow, USSR. (hbf)

90:4075Croft, W.s. and J.S. Prouty (eds.), 1989. Energy into

the '90s. Transactions, Thirty-ninth annualmeeting of the GCAGS, AAPG regional meeting, and the thirty-sixth annual meeting of theSEPM Gulf Coast Section, October 25-27, 1989Corpus Christi, Texas. Trans. Gulf Cst Ass. geol.Socs, 39:593pp; 58 papers.

This collection of technical papers treats a diversityof topics loosely related to the occurrence ofhydrocarbons in the Gulf Coast states and Gulf ofMexico. Subject matter ranges from overviews andgeneral theoretical treatments to specific field andlaboratory investigations and applications. Thestudies included provide a state-of-the-art perspective on the use of stratigraphy, sedimentation,seismicity, structure, geothermal history, paleoenvironmental reconstructions, geomorphology, petrology, and model studies for oil exploration andproduction. (hbf)

90:4076Li, Desheng et al., 1990. Developments in the

petroleum geologyof People's Republic of China.J. Petrol. Geol., 13(1): l12pp; 8 papers.

The issue provides an update on petroleum developments in the major Chinese oil-producing TarimBasin in northwestern China, the Chaidam Basin inthe central province, and the South China Sea and

634 D. Submarine Geology and Geophysics OLR (1990) 37(7)

East China Sea basins. An account of the formationof the Mesozoic-Cenozoic basins and a descriptionof a new, numerical, sensitive kerogen-type index arealso included. (hbf)

90:4077Li, Desheng, 1990. Recent advances in the petroleum

geology of China. J. Petrol. Geol., 13(1):7-18.

China's petroleum geology has recently advanced in(1) the study of non-marine facies hydrocarbonaccumulations and of tectonic types of oil- andgas-bearing basins; (2) facies studies of MesoCenozoic lacustrine deposits; (3) the theory andpractice of composite megastructural oil. and gasreserves in the Bohai Gulf Basin; and (4) in researchon buried-hill oil and gas traps. Future in-depthpetroleum-geological studies and continuing exploration activities will ensure that further oil and gasreserves will be located. Scientific Res. Inst. ofPetroleum Explor. and Develop., Ministry of Petroleum Indust., PO Box 910, Beijing, People's Republicof China.

90:4078Liang, Dehua and Zonghui Liu, 1990. The genesis of

the South China Sea and Its hydrocarbon-bearingbasins. J. Petrol. Geol., 13(1):59-70.

Formation of the South China Sea was primarilycontrolled by the NeoCathaysian and Nanhai tectonic systems that are associated with the first andsecond phases of spreading in the South China Sea,where 33 sedimentary basins have so far beenlocated. Basin generation and development wastectonically controlled, and four basin types havebeen identified: tensile, tensile-shear. compressive,and compressive-shear. Tensile and tensile-shearbasins in the Nanhai system, and the compressivebasins in the NeoCathaysian system, have the mostpromising oil and gas potential. No.2 Mar. andGeol. Invest. Brigade, Ministry of Geol. and Min.Resour., PO Box 1180, Guangzhu, People's Republicof China.

90:4079Murray, T.H. Jr. (chairman, AAPG Committee on

Statistics of Drilling) et al., 1989. World energydevelopments, 1988. Am. Ass. Petrol. Geol. Bull;73(IOB):39Ipp; 32 papers.

Significant oil and gas exploration and productionactivities in the U.S. and Canada, and developmentsin Australia, New Zealand, the southwest Pacific,Africa, Israel, the Middle East, Far East, South andCentral America, the Caribbean, and Mexico, alongwith developments in the energy minerals (coal,geothermal, oil shale, and uranium), are summarized

by writers who can provide local detail for theirrespective geographic areas and subject matter. Theindividual reports are based on well data, land statusreports, production statistics, and geophysical activity information obtained from diverse sources. (hbf)

90:4080Summons, R.E. and L.L. Jahnke, 1990.Identification

of the methylhopanesin sediments and petroleum.Geochim. cosmochim. Acta, 54(1):247-251. Bureau of Min. Resour., GPO Box 378, Canberra,ACT 260I, Australia.

90:4081Wang, Guoehen, 1990. Prospective petrollferous

areas in the East China Sea Basin. J. Petrol.Geol., 13(1):71-78.

The East China Sea Basin is a major Cenozoic basin,with a sedimentary fill >10,000 m thick. Theevolution of the basin is divisible into four stagesdown-faulting, fault-sagging, down-warping anddraping. Tectonic movements were characterized bymultiple episodes of spatial differentiation, andtectonic units are divisible into longitudinal zonesand latitudinal blocks. Various types of trap structure are present, including Tertiary sandstone traps,basement traps, and reef traps. Res. Ctr. of OffshorePetroleum Explor. and Develop., China Natl. Offshore Oil Corp., Xincheng County, Hebei, People'sRepublic of China.

D340. Manganese nodules, etc.

90:4082Hartmann, M. et al., 1989. The manganese nodules of

the Kane Gap (east Atlantic): indicators ofsedimentation-erosion changes. GeologischeRdsch; 78(3):943-958.

Comparing the nodule structure with the stratigraphy of the related sediments, the following conclusions are drawn concerning the sedimentationprocesses during the last 4-6 myr. During the firstphase of only a few hundred thousand years, thenodules grew very quickly (7 to >18 mm/Ma),Fe-rich hydrogenetic material formed the internalsections of the nodules during this time. Slowingdown of the bottom currents, resulting in depositionof thin sediment covers for short intervals, causedthe character of the nodules to change to a morediagenetic composition. The growth rates werereduced to about I to 2 mm/Ma. The time ofslowing is roughly J to 4 MaBP. Geol. Palaontol.und Mus. der Univ., Olshausenstr. 40,0-2300 Kiell,FRG.

OLR (1990)37 (1)

90:4083Luo, Shangde, Lei Wang and Yipu Huang, 1989.

Studies on diffusion and profiles of elements indeep-sea manganese nodules. Acta oceano/. sin.(English version), 8(3):391-400. Dept. ofOceanogr., Xiamen Univ., Xiamen, People'sRepublic of China.

90:4084Shterenberg, L.Ye. et aI., 1989. Sedimentary and

hydrothermal ferromanganese on the ShatskiyRise. Int. Geol. Rev; 31(9):951-957.

Nodules 6-8 em in diameter, dredged from waterdepths of 4200 to 3200 m at 36°34 '~, 159°08 'E,consisted of cores of basalt surrounded by 1.5-3 cmthick shells of Mn and Fe oxides. The basaltic cores,transformed volcanic glasses and plagioclase, havebeen extensively altered by secondary processes, andcavities within them contain black, sof t ore mineralswith Mn:Fe ratios of 2lO to 350. Hydrothermalgrowths found in the vesicles were identified asbarium-rich todorokite. The mineralized shells, onthe other hand, were composed largely of asbolanebuserite and vemadite. The evidence suggests thatthe shells of the nodules formed as the edges of thebasalt were altered. Inst. of Geol. Sci., Acad. of Sci.,Moscow, USSR. (hbf)

635

90:4085Takematsu, Noburu, Yoshio Sato and Shiro Okabe,

1989. Mechanisms of incorporation of rare earthelements into ferromanganese concretions. Mer,Tokyo, 27(1-2):41-52.

It has been shown tbat enrichment of REE infe rromanganese concretions decreases from a maximum in nodules of hydrogenous origin to lesseramounts in nodules of oxic diagenetic, suboxicdiagenetic, and hydrothermal origins. These d ifferences are explained by lower concentrations ofREE in interstitial waters relative to seawater or togreater retention of REE than of transition metalsduring diagenesis. It is suggested that incorporationof REE into both Fe-oxide and Mn-oxide phases isrelated to the adsorption of free REE ions on oxidesand the proportion of free REE ions. Ce content ofthe nodules is controlled by redox potential of theenvironment. lnst. of Phys. and Chem. Res., Wakoshi, Saitama, 351·01, Japan. (hbf)

D370. Miscellaneous

90:4086Delaney, J.S., 1989. Lunar basalt breccia identified

among Antarctic meteorites. Nature, Lond;342(6252):889-890. Dept. of Geo!. Sci., RutgersUniv., New Brunswick, NJ 08903, USA.

E. BIOLOGICAL OCEANOGRAPHY

EIO. Apparatus and methods

90:4087Behne, Dietrich, 1989. New developments in trace

element analysis in the life sciences. Z . analyt.Chern., 335(7):802-805.

Application of trace element analysis to the lifesciences increasingly requires analysis of morespecific sample components (particular cell types,subcellular fractions, and molecules) and concomitant analysis of pertinent biological or biochemicalparameters. The new developments in samp le handling and analysis necessary to meet these needs,and the problems that may arise are discussed, andillustrative examples are presented. Particular attention is paid to the problems of contamination and

certification of suitable standard reference materials.Hahn Meitner lnst. Berlin, Postfach 390128, D-lOOOBerlin 39, FRG. (gsb)

91):4088Hara, Shigerni tsu and Eiichiro Tanoue, 1989. Simul

taneous staining with three fluorescent dyes ofminute plankters on an agarose gel filter. DeepSea R es; 36(IIA): 1777-1784.

A new method, employing an agarose gel filter andtriple staining with fluorescent dyes, was developedfor observation and enumeration of planktonicmicroorganisms in the size range 0.2-20 /Lm from avariety of niches in the marine ecosystem. Dansylchloride was used to stain the cell-surface proteins,Calcofluor white was used to stain cellulose and

Date post:	30-Dec-2016
Category:	Documents
Upload:	phamlien
View:	217 times
Download:	2 times

Submarine geology and geophysics

Documents