1. INTRODUCTION AND EXPLANATORY NOTES · 2007. 5. 15. · S.T. Serocki, Scripps Institution of...

1. INTRODUCTION AND EXPLANATORY NOTES

S.O. Schlanger, University of California, Riverside, CaliforniaE.D. Jackson, U.S. Geological Survey, Menlo Park, California

A. Kaneps, Scripps Institution of Oceanography, La Jolla, Californiaand

S.T. Serocki, Scripps Institution of Oceanography, La Jolla, California

PRECRUISE PLANNING

Leg 33 of the Deep Sea Drilling Project was the fourthof five cruises planned for the 1973-1974 drillingprogram of the Glomar Challenger in the Pacific. Themain purpose of this leg was to investigate the geologichistory of one of the linear submarine ridge and islandchain systems that have given rise to so much specula-tion from the days of J.D. Dana to the present.

Leg 33 grew out of a proposal to the JOIDES Plan-ning Committee for a "Leg Hot Spot" (Schlanger,Winterer, and Lancelot, memo. 1971). At that timeMorgan (1971, 1972a, b) had extended Wilson's (1963)hypothesis that linear island chains and aseismic ridgeswere formed above fixed hot spots in the mantle, andthat, when viewed from a time framework, these chainsmapped plate motion. Morgon (1971, 1972a, b) pro-posed that such chains were fed by thermal plumes, andthat their bends, or elbows, marked changes in platedirection. He specifically included the Line Islands-Tua-motu Chain as having resulted from one of his fixedplumes. The original "Leg Hot Spot" proposal was de-signed to test these ideas by drilling along the flanks ofislands, seamounts, and ridges in the Line Islands andthe Tuamotus. Site 165, drilled on Leg 17, in a turbiditeapron northwest of Kingman Reef in the Line Islandssnowed that such flank sites revealed a great deal aboutthe history of nearby islands. The turbidites containedskeletal debris of reefal and shallower water ridge crestorigin and volcaniclastic sequences that marked thehistory and cessation of volcanism at that point alongthe island chain. Since the original proposal was written,many new data have been assembled by a number ofworkers, giving new insights into what now appears tobe a much more complicated linear island chain genera-tion mechanism than was originally envisioned byMorgan and Wilson. Shaw and Jackson (1973), for ex-ample, believe that these chains are localized bygravitational anchors rather than by thermal plumes.Many of these newer ideas on linear island chain genera-tion are based on data from the Hawaiian-EmperorChain; very little new data have been produced from theLine Islands-Tuamotu Chain, the longest of the so-called bent island chains in the Pacific Basin.

The primary objectives of Leg 33 were:1) To determine the ages and geologic histories of

segments of the Line Islands-Tuamotu Chain by drillinginto the turbidite fans that drape around them. Based onsuch new data, we considered it possible to determinewhether the two chain segments are indeed temporarily

linked at an elbow, whether they overlap in age, orwhether they are two separate "subchains."

2) To determine the extent and rate of the verticalmotions undergone by these islands through time asthey traveled away from the site of generation.

3) To gain a better understanding of the developmentof the sedimentary aprons that surround the islands.

4) To add to our information on the origin andgeologic history of oceanic plateaus and rises by drillingthe Manihiki Plateau.

Secondary objectives of Leg 33 included:5) Petrologic objectives.6) Paleooceanographic objectives.7) Biostratigraphic objectives.8) Geophysical objectives.9) Operational objectives.Six primary sites and several alternate sites were

originally selected (Figure 1 and Table 1). One primarysite, 33-1, provided a location close to Honolulu for theproposed first sea trials of the heave compensationsystem which was, among other things, designed to im-prove the quality of cores recovered in soft sedimentsand to extend bit life. Four primary sites, 33-2, 33-3, 33-4, and 33-6, were selected to test ideas relevant to linearisland chain formation; and one primary site, 33-5, wasselected to solve problems relevant to oceanic rise andplateau genesis.

Cruise Objectives

Linear Island Chain Genesis and Age

Since Morgan's (1971,1972a, b) proposals, Jackson etal. (1972) showed that volcanism along the southeasternHawaiian Islands has been episodic. Shaw (1973)calculated the volumes of the Hawaiian Islands, showedthem to correlate with the episodic ages, and predictedeven greater episodicity among undated seamounts inthe northwestern part of the chain. Winterer (1973)pointed out discrepancies between the rate of movementof the equatorial sediment bulge and the apparent rateof movement of the Hawaiian Chain. Clague andJarrard (1973a) compiled a list of minimum ages of mostPacific Island chains, and found them partially atvariance with the Morgan hypothesis. Clague andDalrymple (1973) dated Köko Seamount, and, althoughaware of the episodic nature of the volcanism, predictedan age of 42-44 m.y. for the Hawaiian-Emperor bend.Scholl et al. (1971) reported the age of Meiji Seamount,which may be the northernmost of the Emperorseamounts as 72 m.y. Using these values and volumetric

S. O. SCHLANGER, E. D. JACKSON, A. KANEPS, S. T. SEROCKI

I I I I I I I I I I I I I I 1 I I I I I I I Kl 1 I I I I I I I I I I I I I

20c

150° 120c

Figure 1. Location of proposed sites to be drilled during Deep Sea Drilling Project, Leg 33.

Depths in Fathoms

data, Bargar and Jackson (1975) calculated the eruptionrate along the Emperor segment as 0.012 km3/yr and ofthe Hawaiian segment 0.018 km3/yr. There are growingdata that suggest that "hot spots" are not fixed in time,as Wilson and Morgan contended, but that they moveslowly with time (Clague and Jarrard, 1973a; Molnarand Atwater, 1973). Shaw and Jackson (1973) proposedthat linear island chains in the Pacific are stabilized bygravitational anchors rather than thermal plumes,anchors that would move slowly with time, and that theapparent periodicity of volcanism is caused by shearmelting above an anchor free to flow or counterflow inthe asthenosphere. Thus, while data principally derivedfrom the Hawaiian-Emperor Chain proliferate, and arebeing extended to other linear island chains, little wasknown about the Line Islands proper or their relation tothe Tuamotus. Clague and Jarrard (1973b) pointed outthat the Line Islands do not lie exactly on the greatcircles of the Emperors or the Marshall-Gilbert-Ellicechains to which they are supposedly related. They arecomplicated by the "Line Cross," a bathymetric featureof obscure origin. Clague and Jarrard (1973b) reportedonly five ages from the entire Tuamotu-Line Chain,some of them questionable. These dates, which rangefrom 37.5-80 m.y., are not consistent with an even rate

of progression of volcanism along the chain. Weplanned to devote four continuously cored holes (33-2,33-3, 33-4, and 33-6) to the Line-Tuamotu Chain towardresolving this inconsistency.

History of Vertical Motion of the IslandsPrevious studies on the diagenetic history of the

limestone columns that underlie atolls show that theiremergence-submergence history is preserved in the formof alternating zones of aragonite-free, calcite-rich rocksand aragonite-rich rocks separated by "solution uncon-formities" (Schlanger, 1963). The diagenetic state of theskeletal debris of shallow-water and reefal origin presentin the turbidite facies to be drilled at Sites 33-2, 33-3, 33-4, and 33-6 was planned to indicate periods ofemergence (uplift) and submergence (subsidence) of theadjacent island chain.

Sedimentary Fan DevelopmentThe central part of the Line Islands Ridge is marked

by a spectacular development of sedimentary fans bothto the east and west of the main ridge. Seismic profilesshow that up to 800 meters of well-stratified sedimentare present above acoustic basement. At Site 165 on Leg17 it was found that much of this fan material shows

INTRODUCTION AND EXPLANATORY NOTES

TABLE 1Proposed Sites for Leg 33 - Central Pacific

Site

1

2(314)

3(315)

3a

4(316)

5 (317)

5a

6(318)

6a

7a

Area

Kaula Island Fan

Johnston Island Trough

Fanning Island Fan East

Fanning Island Fan West

Line Islands South

Manihiki Plateau

Manihiki Plateau

Tuamotu Ridge

Tuamotu-NW

Tuamotu Trough

Coordinates

21°N161°W

16°N168.5°W

4.2° N158.4°W

3.3°N160.5°W

0.8°S156.1°W

11°S162.2°W

12.8°S162.3°W

15.2°S146.8°W

15.5°S149°W

17.8°S144°W

WaterDepth

(m)

4500

5100

4200

4500

4700

2560

2400

2600

4200

4000

DrillingDepth

(m)

300

600

720

630

650

900

800

670

225

460

Priority

1

1

1

2

1

1

1

1

2

2

Major Objectives

Sea trial of heave compensator;geologic history of Kaula Island

Geologic history of Johnston Island;turbidite fan sedimentology

Geologic history of central LineIslands; turbidite fan sedimentology

Geologic history of central LineIslands; turbidite fan sedimentology

Geologic history of southern LineIslands

Geologic history of a major rise;facies comparison with Shatsky andMagellan rises; heat flow measure-ments

Geologic history of a major rise;facies comparison with Shatsky andMagellan rises; heat flow measure-ments; this site is alternate forSite 33-5

Petrology of Tuamotu basalts;geologic history of Tuamotu atolls

Petrology of Tuamotu basalts;geologic history of Tuamotu atolls

Geologic history of central TuamotuChain

aMay be drilled on Leg 34.

cyclical sedimentation units of probable turbidite origin.Site 33-3 was planned for maximum penetration andcore recovery of a fan so that its sedimentologicalhistory could be studied.

Oceanic Plateau and Rise GenesisManihiki Plateau, Shatsky Rise, and Magellan Rise

represent three major geologic features that areanomalous in terms of a simple ridge-crest model of sea-floor generation. The age and mode of formation ofsuch features will have to be included in anysophisticated theory of sea-floor evolution. Therefore, itwas important to completely sample the sedimentarycap and core the basement basalt of these rises andplateaus. Adequate coring of the Magellan Rise on Leg17 resulted in the documentation of its Late Jurassic toQuaternary history of pelagic sedimentation. A com-plete penetration of Shatsky Rise was planned for Leg32. An evaluation of the Manihiki Plateau was plannedfor Leg 33.

Petrologic ObjectivesThe thickness of sediment which overlies basalt at Leg

33 drill sites posed a problem. It was postulated that theentire Line Islands Chain had passed through nutrient-rich equatorial waters, and that the individual edificeswere partially blanketed by thick sediment sequenceswhich must be penetrated before basalt could be cored.At Sites 33-1, 33-3, and 33-4, it was recognized that if

basalt were recovered, it would be difficult to saywhether it represented derivation from shield-shapededifices or was older ocean floor. It was decided that,unless coring or seismic profiling gave new information,drilling into basalt at these sites would be minimized.Site 33-2, on the other hand, appeared to overlie olderoceanic" crust, and, time permitting, we planned to drillbasalt until bit failure. At Site 33-5, on the ManihikiPlateau, basalt again would be drilled as time permitted.Finally, at Site 33-6, previous seismic profiles seemed toclearly indicate edifice material at the drill site, and aneffort needed to be made to recover as much volcanicrock as possible. We expected typical deep-sea basalt atSites 33-2 and 33-5, although it was thought it might bemuch altered (Salisbury and Christensen, 1972; Bass etal., 1973). At Site 33-6 it was thought to be interesting tonote whether or not we encountered alkalic rocks typicalof Hawaiian-type shields, or Hawaiian-Icelandic-typetholeiite.

Paleooceanographic ObjectivesThe complete penetration of the Magellan Rise on

Leg 17 (Site 167) revealed that the 1185-meter-thicksedimentary cap contains an almost uninterruptedpelagic record spanning Late Jurassic to Quaternarytime.

At the time Leg 33 was planned, Leg 30 was engagedin drilling the Ontong-Java Plateau, Leg 32 had pro-posed to drill Shatsky Rise, and, together with our pro-


posed Site 33-5 on the Manihiki Plateau, would providefour relatively complete stratigraphic sections of themajor Pacific plateaus. Their sediments would repre-sent deposition covering a broad latitudinal span. Thepaths of these rises through the various water masses ofthe Pacific since late Mesozoic time should be reflectedin (1) the lithofacies sequences developed on each in thestratigraphic column, and (2) in the differences in litho-facies within isochronous zones between each column.Further, these thick pelagic sections offer excellentmaterial for isotope studies (Coplen and Schlanger,1973) that are beginning to show the existence ofworldwide isotope events having possible paleo-temperature significance.

Biostratigraphic ObjectivesNo sites had been selected primarily for biostrati-

graphic objectives although charting latitudinal aspectsof fossil assemblages was an important consideration forthe Manihiki Plateau drill site. In addition, the turbiditefan sites would penetrate intervals where pelagic faunaland floral elements have been cosedimented with boththe reefal and bank facies as well as ridge crest elements,thereby increasing our knowledge of the correlationsbetween planktonic and benthonic fossils.

Geophysical ObjectivesHeat flow measurements were needed to establish ad-

ditional reliable oceanic control points, to determine ifheat flow varies with depth, and to establish the tem-perature regimes of diagenesis in pelagic sediments.Prior to Leg 33 (R.P. von Herzen, letter dated 24 July1973), a maximum of only three to four reliable down-hole temperatures had been obtained for any DSDP site.Rather than collect scattered data, Leg 33 agreed toattempt to obtain 8 to 10 downhole measurements atone site, 33-5, on the Manihiki Plateau, but heat flow in-strumentation was not onboard the Challenger when theleg left Honolulu.

Operational ObjectivesDue to delays in the installation of the heave compen-

sation unit, we were informed that its testing would oc-cur on Leg 33. Site 33-1 was selected as a test localitybased on considerations of water depth, closeness toHonolulu, and sediment thickness. The site, while notpart of the original cruise proposal for Leg 33, wouldprovide valuable data on the evolution of the Kaula-Nihoa-Kauai triplet in the Hawaiian Island Chain, andthus contribute data to the problem of linear islandchain formation.

CRUISE RESULTS

Geologic ResultsGlomar Challenger steamed from

November 1973, drilled eight holes at2), and docked at Papeete, Tahiti, oncomplete Leg 33 of the Deep SeaPreplanned Site 33-1 was abandonedoperational problems (see followingChallenger proceeded directly from

Honolulu on 2five sites (Figure17 December, toDrilling Project,because of initialsection) and theHonolulu to the

Johnston Island Trough. The drilling and coring sum-mary of Leg 33 is summarized in Table 2.

Preplanned Site 33-2 (Site 314)Site objectives were reduced on leaving Honolulu (due

to a substantially shortened leg that resulted from delaysin the installation of the heave compensator) to a spot-coring program in order to penetrate the estimated 650meters of sediment overlying basement at this site. Ac-tual penetration at the site was 45 meters; drilling dif-ficulties culminated in the bending of the bumper subsof the bottom-hole assembly and the site was aban-doned. The section from the mudline to 17.5 meters, andmost likely to a depth of 35 meters, consisted of brownzeolitic clay rich in phillipsite and containing abundantreworked late Neogene, Paleogene, and Cretaceousfaunal elements. This soft clay overlay harder claystoneand porcellanite probably of middle to late Eocene agethat was found at 35 to 45 meters depth. The porcel-lanite was diagenetically produced from an originallyforaminiferal and nannofossil-bearing sediment. Therelict carbonate, in the form of nannofossils andrecrystallized (possibly planktonic) foraminifera in theporcellanite, indicated that the Johnston Island Troughmay have been shallower than the foraminiferal solutiondepth during middle to late Eocene time (the presentdepth is 5225 m).

By way of contrast, at Site 164 (present depth 5499 m)the stratigraphically equivalent section was probablydeeper than the carbonate-compensation depth or wasbeneath a region of extremely low fertility. At Site 68(present depth 5467 m) the situation was similar to thatat Site 164. It seemed therefore reasonable to proposethat the bottom of the Johnston Island Trough wasalready shallower by middle-late Eocene time than thebasin to the east, in which Sites 165 and 68 are located.

Preplanned Site 33-3 (Site 315)After four cores were cut in Hole 315, in the interval

from 0.0 to 37.5 meters subbottom depth, and 17.2meters of core consisting of Pleistocene to lowerPliocene oozes were recovered, the drill string had to bepulled because the ship had moved too far away fromthe beacon. Hole 315A was respudded at the same loca-tion and water depth: total depth of this hole was 1034.5meters, of which 323.0 meters was cored and 130.5meters recovered. The section consisted of (1) cyclicallybedded foraminiferal and nannofossil ooze from 0 to 56meters, of Quaternary through Pliocene age withinwhich a Pliocene hiatus was found; (2) variegated pur-ple, white, and green nannofossil ooze from 56 to 710meters, which became chalky near a depth of 370meters, of Oligocene to late Miocene age, and whichcontained a Miocene hiatus at a depth of about 454-512meters; (3) Eocene through upper Campanian claystone,chert, and limestone from 710 meters to 844 meters, asection whose base was dated as near the middle-upperCampanian boundary, and which contained a unit ofreefal debris at about 800 meters; (4) middle and upperCampanian volcaniclastic sandstones and micriticclaystones that extended from 844 to 901 meters and dis-played a wide variety of turbidite structures; the base ofthis unit appeared to be close to the Campanian-


1 ' '

20c

20c

M ' ' ' I " « ' M '« I I I I I I I I I I I I I i I | I i I I | I I I I | i i I

Manihiki Plateau

i i i i i i i i i t i i i I i i i i I i i K I I i i i i l i i i i l i i i i I i i i i I i i i i m i i i i i i i I i i i i I i I I I I Il • • • • lDepths in Fathoms

Figure 2. Location of holes drilled during Leg 33.

TABLE 2Deep Sea Drilling Project Site Summary, Leg 33

Hole Latitude

Johnston Island Trough

314 15° 54.76'N

Fanning Island Fan East

315 4° 10.26'N315A 4° 10.26'N

Line Islands South

316 0° 05.44'N

Manihiki Plateau

317 ll°00.09'S317A ll°00.09'S317B ll°00.09'S

Tuamotu Ridge

318 14°49.63'S

Total

Longitude

168° 28.07'W

158° 31.54'W158° 31.54'W

157° 07.71'W

162° 15.78'W162° 15.78'W162° 15.78'W

146° 51.51'W

WaterDepth

(m)

5225.5a

4164a

4164a

4464.5a

2625a

2622a

2622a

2659a

Numberof

Cores

3

434

30

33445

32

185

CoresWith

Recovery

0

231

29

33342

32

172

PercentWith

Recovery

0

5091

97

1009793

100

93

Cored(m)

17.5

37.5323.0

285.0

28.5313.5424.5

298.5

1728.0

Recovered(m)

<l.O

17.2130.5

102.8

19.2163.3308.0

147.1

888.1

Recovered(%)

<l.O

59.640.5

36.4

67.751.771.6

49.3

51.5

Drilled(m)

27.5

47.5711.5

552.0

323.0630.0

0

446.5

2747.5

TotalPenet.

(m)

45.0

85.01034.5

837.0

351.5943.5424.5

745.0

4466.0

Avg.Rate

Penet.

165.0

98.026.0

21.0

13.010.56.3

25.7

29.0

TimeOn

Hole(hr)

42.5

32.0124.5

115.0

26.589.567.0

77.0

574.0

TimeOnSite(hr)

42.5

156.5

115.5

183.0

77.0

574.0

aDrill pipe depth.

Santonian boundary; (5) ferruginous claystones andgraded volcanogenic sandstones in the interval 911-996meters, of Santonian age. Beneath these sediments 38meters of basalt was cored but less than 8 meters was

recovered. Parts of at least sixfrom 1.5 to 2.0 meters thick,cores. All the basalt was highlybe determined whether it had

flow units, each rangingwere recognized in thealtered, and it could nottholeiitic or alkalic af-


finities (see Jackson et al., this volume). It is suspectedthat at least some of the units were alkalic. Based on ex-trapolated sedimentation rates, we concluded thatvolcanism ceased at Site 315 about 85 m.y. ago (seeLanphere and Dalrymple, this volume).

Preplanned Site 33-4 (Site 316)The section consisted of (1) cyclically bedded white

foraminiferal-nannofossil ooze of Quaternary age be-tween 0.0 and 2.0 meters depth, (2A) Quaternarythrough middle Miocene varicolored foraminiferal-nannofossil oozes between 2.0 and 267 meters depth,(2B) middle through lower Miocene varicolored chalkbetween 267 and 380 meters depth, (3) lower Miocenethrough Paleocene interbedded chalks and cherts (local-ly dolomitic) between 267 and 580 meters depth, and (4)interbedded chalk, limestone, and chert, underlain byvolcanogenic debris, from 580 meters to the bottom ofthe hole at 837 meters, which ranged in age from middleMaestrichtian to early Campanian. Again, based on ex-trapolated sedimentation rates we concluded that vol-canism ended here about 81-83 m.y. ago.

Preplanned Site 33-5 (Site 317)In order to avoid using reentry techniques and

minimize bit wear, a drilling strategy was adopted thatinvolved (1) washing down to hard rock, (2) coring con-tinuously to and into basement, (3) pulling the drillstring, respudding with a fresh bit, and (4) continuouslycoring the upper ooze and chalk section. Hole 317 wasterminated at 351.5 meters below the bottom because abolt accidentally fell down the drill pipe and preventedrecovery of the core barrel. Hole 317A was then spud-ded and was successfully completed in basalt at 943.5meters. Hole 317B, drilled to sample the previouslybypassed upper section, was continuously cored until afragment of a pump was washed into the drill pipe andprevented retrieval of the core barrel at a depth of 424.5meters; that left a gap of 129.5 meters between thedeepest cores of 317B and the shallowest level of thecontinuously cored part of 317A. The section at Site317, as reconstructed from all three holes, consisted of(1) grayish-orange, white, and bluish-white nannofossiland foraminiferal ooze, firm ooze, and chalk, of Quater-nary to middle Oligocene age, from 0.0 to 303.5 subbot-tom depth; (2) light-colored foraminiferal nannofossilooze, chalk, and chert, of middle Oligocene to Aptianage, from 303.5 to 647 meters depth which containedonly rare benthonic forams in its lower part; and (3)greenish-black to red volcanogenic sandstones, silt-stones, and mudstones of Early Cretaceous age, from647 to 910 meters in depth, which were very poor infossils except for some Aptian fossils in the uppermostpart of the section. Between 600 and 700 meters depth,including parts of Units 2 and 3 above, well-preservedpelecypods were observed. Among these some shallow-water forms were thought to exist, although they werenot identified or dated with certainty aboard ship.Below 910 meters, basalt was encountered directlybeneath the volcanogenic sediments. Parts of 10 basalt-flow units lay between 910 and 943.5 meters, the deepestlevel reached in drilling. Thin, baked volcanogenic silt-stones lay between four of the uppermost flow units.

The flow units appeared to be of the oceanic tholeiitetype; their exceedingly vesicular character suggestsoriginal deposition in shallow water, or very highoriginal gas content. The deepest volcanogenic sedi-ments and the basalts beneath them were older than 107m.y. B.P. and could, we felt, be as old as 120 m.y. B.P.

The heave compensator was tested at this site and wasused in coring the greater part of Hole 317B. Recoverywith the heave compensator was as good as that usuallyobtained in comparable lithologies. However, fromthese preliminary tests, cores taken with the compen-sator at this site appeared to be about as much deformedas those taken without it.

Preplanned Site 33-6 (Site 318)Unfortunately time on this site was limited and base-

ment was not reached. The section at Site 318 consistedof five lithologic units: (1) nannofossil foraminiferalooze from 0 to between 35.5 and 64.5 meters subbottomdepth, of Quaternary to late Pliocene age, includinggraded layers of shallow-water reefal debris; (2)foraminiferal-nannofossil firm ooze to soft chalk, frombetween 35.5 and 64.5 to between 245 and 264 metersdepth, of late Pliocene to middle Miocene age, includinga few layers of sand-size altered volcanogenic glass; (3)firm, nannofossil-foraminiferal chalk, from between 245and 264 to between 416 and 435 meters depth, of earlyMiocene (with a minor hiatus) to early Oligocene age,also contained some volcanogenic and skeletal debris;(4) nannofossiliferous and foraminiferal limestone withcommon chert nodules and lenses, from between 416and 435 to between 530 and 549 meters, of earlyOligocene through late Eocene age, which containedsome volcanogenic debris, and, near its base, skeletaldebris of shallow-water origin; this unit contained amiddle to early Oligocene hiatus; and (5) green and grayclayey limestones, siltstones, and sandstones, as gradedbeds, from between 530 and 549 to 745 meters, of middleand early Eocene age. The heave compensator was leftin the drill string, and alternate cores throughout thesection were taken with it locked out for one core and inoperation for the next. This program was followedthrough the first 20 cores taken at the site. Initial com-parative results again indicated that core recovery anddeformation appeared unchanged with the heave com-pensator.

ConclusionsThe precruise planning for Leg 33 was in part based

on the results from Site 165. Sites 314, 315, and 316 wereselected to provide, along with Site 165, four "cessationof volcanism" ages along the entire Line Islands Chain.Unfortunately, Site 314 failed to provide data relative tothe hot-spot problem. However, Sites 165, 315, and 316did provide some evidence that the Line Island Chaindid not fit into a simple hot-spot model (see Dalrympleand Lanphere, this volume, and Jackson and Schlanger,this volume, for a postcruise evaluation of this prob-lem).

Site 315 bore a strong resemblance to Site 165 exceptthat the Eocene section at Site 315 proved to be muchthicker than the Eocene section at Site 165 and that theequivalent of the very thick Miocene and post-Miocene

10


section present at Site 315 had apparently been erodedat Site 165. The date of cessation of flow-type volcanismat the two sites appeared to have been nearly identical,even though they are nearly 800 km apart along the LineIslands Chain. We concluded that if the Line Islandsedifices or their debris were sampled at only these twosites, then volcanism along the chain would have to beinterpreted as either grossly episodic or coeval.

The section encountered at Site 316 was quite similarto that found at Site 315, except that the pre-Eocene sec-tion at Site 315 was much thinner than that at Site 316,and the post-Eocene section much thicker (see Cook,this volume). Acoustic profiles between the two sitessuggested that the post-Eocene section thinned gradual-ly, rather than abruptly, from Site 315 to Site 316 (seeSchlanger and Winterer, this volume).

The ages of basaltic flows that underlie Sites 165, 315,and 316, determined by means of extrapolation based onthe oldest fossils found and sedimentation rate data, in-dicated a total possible range of cessation ages of basaltsranging from 79 to 85 m.y. B.P.; these ages appeared tobe coeval within the limits of the uncertainties involvedin the extrapolations. The "basement" ages did notappear to follow a simple pattern; at Site 315, in the cen-tral part of the chain, the basement was thought to beolder than it was at the northern and southern ends ofthe chain. The cessation of major erosion of the volcanicbasement, as determined by fossil ages in volcaniclasticsediments, was also nearly identical in age at Sites 165,315, and 316. Indeed, the maximum thickness ofvolcanogenic sediments at the three sites occurred insediments of middle Campanian to middle Maestricht-ian (see Cook, this volume) age. If the thick section ofvolcanogenic debris at all three sites represented thesimultaneous growth and erosion of nearby Line Islandsedifices, then it seemed apparent that the cessation ofvolcanism at the three sites was roughly coeval, and thechain did not young to the south, at least over 1270 kmalong the chain spanned by the three sites. In fact, thegeological histories of all three sites appear to have beennearly identical from early Campanian time to the pre-sent (see Cook, this volume). Included in the chain'shistory is a Campanian-Maestrichtian reefal phase onisolated edifices on the ridge as evidenced by shallow-water reefal debris of this age found at all three sites (seeBeckmann, this volume). In our opinion, no hypothesisthat requires systematic movement of the Pacific plateover a fixed "hot-spot" beneath it could account for thegeochronology of Line Islands volcanism, and it seemedapparent that these islands and seamounts were formedby a mechanism different from that postulated to ex-plain the volcanic history of the Hawaiian-EmperorChain (see Winterer, this volume, and Jackson andSchlanger, this volume, for postcruise evaluations).

The Manihiki Plateau (Site 317) appeared to occur ina different geological setting from that of a linear islandchain (see Winterer, this volume, and Jackson andSchlanger, this volume). The history of the plateau, asderived from the drilling, began with the extrusion of ex-tremely vesicular tholeiitic basalts of probably oceanicridge rather than of oceanic island type (see Jackson etal., this volume). A section of pelecypod-bearing, but

undated on shipboard (see Kauffman, this volume),sediments 240 meters thick lay between the basalt andcalcareous sediments dated as Aptian. If these relativelybarren sediments were weathered ash, eruptivevolcanism could have persisted to Aptian time; if thebarren section consisted of originally volcanogenicmaterial eroded from previously erupted rocks, activevolcanism could have ended earlier (see Jenkyns, thisvolume). After the eruptive phase, the terrain appearedto have been eroded (see Jenkyns, this volume), afterwhich the plateau subsided and became the site ofpelagic sedimentation. The lack of any shallow-water in-place or transported fauna in the basal sediments wassomewhat puzzling aboard ship because the vesicularnature of the basalt suggested relatively shallow water,and therefore some parts of the plateau should have hadseamounts projecting above the general level of theflows. Subsequent study (see Kauffman, this volume;Jenkyns, this volume) revealed macrofossils indicativeof shallow-water deposition. The islands around the rimof the plateau, such as Manihiki and Suvarov, kept pacewith the rising sea level and became atolls.

The Manihiki Plateau section drilled appeared tocompare much more closely to the Ontong-Java Plateausection than to sections from the Magellan Rise or theShatsky Rise. Both the Manihiki and Ontong-Javaplateaus had younger basement ages (Aptian-Bar-remian[?]) than Magellan and Shatsky (Tithonian-Ber-riasian). Neither the Manihiki (see Cockerham and Jar-rard, this volume) nor the Ontong-Java plateaus ap-peared to have passed through equatorial waters; theMagellan Rise, on the other hand, probably crossed theequator 25-30 m.y. ago, and the Shatsky Rise is reportedto have crossed about 90 m.y. ago. The presence of athick Cretaceous volcanogenic sedimentary section atManihiki contrasts with the thin tuffaceous section thatlies above basalt at Ontong-Java, but we had no reasonto suppose the Manihiki volcaniclastics were not locallyderived (see Jenkyns, this volume).

The geological history of the area around Site 318 inthe Tuamotu Islands could be only partly reconstructedbecause basement was not reached. The deepest sedi-ments penetrated were volcanogenic debris rich in shal-low-water skeletal fragments, mainly large benthonicforams (see Beckmann, this volume); associated nanno-fossils yielded a latest early Eocene age (see Martini, thisvolume). Volcanic edifices in the general area of the siteevidently were built, eroded, and had developed reefs bythat time. Using a minimum age of 50 m.y. ago for theend of flow volcanism at Site 318, and considering suchother ages as were available, it was possible to interpretthe progression of Tuamotuan volcanism, like theHawaiian, as irregular rather than linear. Furthermore,a minimum age of 50 m.y. for the Tuamotu Chain in thearea we drilled was greater than the most recent estimateof the age of the Hawaiian-Emperor bend (42 m.y.).After major erosion and reef formation, nearly con-tinuous pelagic sedimentation took place at the drill site,although several hiatuses were present, during theperiod from early Eocene to Quaternary time. However,abundant reefal debris was deposited as turbidite unitsduring middle Eocene and early Miocene time.

11


OperationsA summary of operations, total time distribution on

Leg 33, and on-site time distribution are given as Table 3and Figures 3 and 4, respectively.

Heave CompensatorThe heave compensation system was installed and

partially tested at dockside during the Honolulu portcall. Installation was complete except for the stabilizerarms which were fabricated by the drill crew while un-derway. Installation time was underestimated by thecontractor and 23 days were required for installation.Welding and installation of high pressure piping re-mained on the critical path during installation. Exceptfor minor leaks, which were readily repaired, the systempassed Coast Guard Certification tests.

Following crew orientation and system checkout,the compensator was tested at dockside. Test loads of415,000 pounds and 600,000 pounds were pulled againstsubstructure beams and the compensator was strokedusing the drawworks to simulate heaves to 12 feet. Datawere incomplete because test time was reduced to per-mit ship departure for Leg 33 on 2 November. The dataobtained, however, showed good correlation withpredicted performance and indicated the system had thepotential to meet design specifications of ±0.625% loadvariation at 400,000 pound drill-string load.

A GMI and a Brown Brothers engineer were aboardfor Leg 33 to provide service and analyze system per-formance. Testing, trouble-shooting, and field modifi-cations were made while underway with minimum in-terference to normal drilling operations. The fabricationof stabilizer arms proved time consuming and delayedoperational testing of the system until Site 316.

After field modifications of the raise-lower circuit andlocking latches and troubleshooting of the Olmstead

Figure 3. Time distribution for the whole of Leg 33.

safety valve, the crew received familiarization training atSite 317. At Sites 317B and 318, the system was testedand monitored for performance. Performance data wereobtained by recording instrumentation from remotetransducers and visually recording drill data from thedriller's console. For example, with a total hook load of285,000 pounds, bit weight of 20,000 pounds and heavesto 6.5 feet, the system compensated with an averageweight fluctuation of ±1500 to ±3200 pounds. Foranalytical and testing purposes, a partial air bank usingonly 28% of the available air volume was used, and per-

TABLE 3Summary of Operations

Total days Leg 33 (10 October-17 December 1973)Total days in portTotal days cruisingTotal days on site

Trip timeDrilling timeCoring timeMechanical downtimeWaiting on weatherOther miscellaneous time

5.83.6

12.8001.9

Total distance traveled (nautical miles)Average speedSites investigatedHoles drilledNumber of cores attemptedPercent of cores with recoveryTotal penetrationTotal meters drilledTotal meters coredTotal meters recoveredPercent of core recoveredPercent of total penetration coredMaximum water depth (m)Minimum water depth (m)

67.723.720.524.1

4004.08.358

185172

4466.02747.51728.0888.151.538.5

52252622 Figure 4. On-site time distribution, Leg 33.

12


formance is expected to improve with full bank opera-tion and minor system adjustments. Performance dataare being analyzed for conformance to specificationsand for contractual acceptance of the system.

Project capability was increased by the installationand use of a heave compensation system which is ex-pected to increase bit life as well as core recovery andquality. At Site 318 the heave compensator was placedin the drill string and used to total depth. In softsediments, alternate cores were taken with the unit com-pensating. Starting at a penetration of 606 meters, hardrock requiring bit weights of 18 to 22,000 pounds wasencountered, and the heave compensator was used con-tinuously to minimize bit wear. Silicified limestones andhard, dense siltstones slowed drilling to as low as 16minutes a meter. The compensator kept variation in bitweight to ±1000 pounds in the mild seas. (Details onheave compensation are in a succeeding section.) The bitwas in excellent condition considering the drilling con-ditions. Cones were tight, only one insert was broken,and the teeth were graded at T-3.

Drill Pipe PingerSea-floor depths for coring are routinely found by

PDR and drill-pipe measurement when actual cores arerecovered. In very soft sediments, accuracy decreasesand coring attempts may begin several tens of metersabove or below the mudline. To improve this accuracy,DSDP has been developing a drill pipe pinger which wassuccessfully used to locate bottom at Site 314. In 5225meters of water, the pinger found bottom with a resolu-tion of ±3 meters. Water depth was 5221 meters of PDRand 5225 meters by drill pipe. The test of the pinger atSite 314 is described further in Chapter 2 (this volume).

The pinger incorporates a 12-kHz transducer and aself-contained electronics package made up to a specialpiston core barrel which can retrieve a 7.5-meter core. Inuse, the self-contained pinger was placed and locked inthe outer core barrel with the transducer protruding 0.3meters below the core catcher. As the assembly waslowered, direct and reflected waves were traced on aGifft recorder. Convergence of the two waves fixes thelocation of the sea floor. The direct wave clearly showseach time a stand of pipe is made up to the drill stringand lowered. Pulse rate of the pinger is 2 sec and therecorder is operated on a 1-sec sweep.

The piston corer assembly is actuated by latchingonto the pinger fishing neck and shearing a releasingpin. This action releases the pinger assembly from theouter core barrel. By maintaining a tension on thepinger and simultaneously lowering the drill string, apiston core can be taken. At Site 314, sea-bottomsediments were too indurated for piston coring, and norecovery was obtained on one attempt.

Drilling and Coring Bottom-Hole AssembliesThe bottom-hole assembly normally used is made up

with a bit, float sub, core barrel, three 8-1/4 in. drillcollars, two bumper subs, two 8-1/4 in. drill collars, one7-1/4 in. drill collar, and one joint of 5-1/2 in. heavy-weight drill pipe. At Sites 317 and 318, where the heavecompensator was used, the bottom-hole assembly was

modified by removing one of the lower two bumpersubs. The upper two bumper subs remained in the as-sembly. With this assembly, drilling could continue tothe objective even if the heave compensator should fail.In the event of a malfunction, the heave compensatorcould be locked up and removed from the drill string.When experience demonstrates the reliability of thecompensator, the only bumper subs needed in the drillstring will be those providing jarring/bumping action inthe case of stuck pipe. At present, with the heave com-pensator in the string (assuming drilling in hard forma-tions which requires the working of both sets of bumpersubs), there is insufficient clearance between the watertable and the connector block to pull the bit off bottomwhen making a connection. However, with one bumpersub out of the assembly when using the compensator inhard formation, it is possible to be 5 feet off bottom dur-ing a connection. This still maintains 5 feet between thewater table and the block with the compensator fully ex-tended.

BitsAll bits were of the journal-bearing, four-cone,

medium-tooth insert type. Bit performance was ex-cellent and no drilling was prematurely terminatedbecause of bit failures. Typically, the bits were pulledwith one loose cone after penetrating some 250 meters ofhard strata requiring 20,000 pounds or more of bitweight to drill. A summary of bit performance is givenin Table 4.

Usually, bearing failure was further advanced thancutting structure failure. Sediment sequences varied atdifferent sites, but in general the lithologic sequence wascomposed of an upper 500 meters of ooze and chalkdrilled with up to 10,000 pounds of weight, 150 metersof chalk and chert requiring 10 to 20,000 pounds ofweight and a hard limestone, siltstone, and basalt inter-val of some 200 meters requiring 20 to 22,000 of weight.As might be expected, sound velocity in the hard stratacorrelated well with drilling time. Correlations betweenlithology, sonic velocity, rate of penetration, and bitweight were used to evaluate bit performance.

The bit at Site 318, where the heave compensator wasused, was in exceptionally good condition. Graded at T-3, B-3, the bearings were still tight and inserted in ex-cellent condition after a penetration of 745 meters. Hardrock, including silicified limestone, was drilled. Of the745 meters penetration, 158 meters required bit weightsof 15 to 22,000 pounds to penetrate.

Coring AssembliesThe "hard formation" slip-type core catcher with

hard facing proved effective and is recommended for usein hard rock sections. On eight cores, plastic socks hadtorn, and patches of plastic had plugged the check valvein the core. Recovery in these instances varied from zeroto about 50%. Consideration should be given to astronger sock material. Two swivel assemblies wereretired because of normal wear and tear. One of theswivels was bent below the bearing assembly, probablyduring repeated joint breakout and was replaced. Thesecond swivel had a failure of grease seals.

13


TABLE 4Deep Sea Drilling Project Bit Summary, Leg 33

Hole

314

315315A

316317317A317B

318

Mfg.

Smith

SmithSmith

SmithSmithSmithSmith

Smith

Size

10-1/8

10-1/810-1/8

10-1/810-1/810-1/810-1/8

10-1/8

Type

F94C 4-CTR

F94C 4-CTRF94C 4-CTR

F94C 4-CTRF940 4-CTRF94C 4-CTRF94C 4-CTR

F94C 4-CTR

SerialNumber

PC204

NW800PC205

NW801NW802NW802PC204

PC206

Cored(m)

17.0

28.0323.0

285.028.5

313.5424.5

298.5

Drilled(m)

27.5

57.0711.5

552.0323.0630.0

0

446.5

TotalPenet.

(m)

44.5

85.01034.5

837.0351.5943.5424.5

745.0

HoursonBit

0.5

0.439.8

39.91.5

31.06.3

28.9

Condition

T-1,B-1

T-8, B-8

T-5, B-5No WearT-2, B-2T-3, B-4

T-3,B-3

Remarks

Suitable for rerun - excellentconditionBroke bottom-hole assembly - lostOne cone loose - 3 medium tight -few inserts brokenOne cone loose

In gage — no loose conesSuitable for rerun — cones mediumtight - in gageUsed compensator — no loosecones - center inserts goodcondition

Sinker bars were shortened up by 10 feet to allowhead room for running into the connector block. To im-prove action, the jars were moved to a point below thesinker bar.

PositioningA summary of the dynamic positioning on Leg 33 is

given as Figure 5, and a beacon summary is given inTable 5.

Performance of the dynamic positioning system wassatisfactory except at Site 315 where failure of thedigital-to-analog converter resulted in the loss of thebottom-hole assembly.

Weather was not a major factor on this leg, althoughsome acoustic interference was anticipated due to chop-py seas generated by 25-35 mph trade winds. Thehydrophones were lowered 10 feet at Sites 315, 316, 317and completely eliminated acoustic losses. Thrusternoise levels became quite high at times. Despite this,good acoustics were maintained at all times.

At Site 314, automatic positioning was used for theduration except for two instances about 12 hr apartwhen the display, main shafts, and thruster commandsbecame slightly erratic. Each time this happened,switching modes from auto to semi-auto and back toauto cured the problem. This did not interrupt drillingas the erratic behavior was not overly pronounced andwas of less than 5 min duration each time.

At Site 315, positioning was initially good inautomatic. Failure of several cards in the digital-to-analog converter caused loss of the bottom-holeassembly due to erroneous display signals after about 14hr on site. Maximum excursion was about 1000 feet.

At Site 315A on 16 November, erratic loss ofacoustics with drastic changes in thrust direction andmagnitude occurred. The ship moved about 400 feet offthe hole before the positioning system could recover.High sustained thrust requirements necessitated goingto semi-auto as thrusters were overloading thegenerators. At daylight, it was discovered that the con-vergence of the equatorial current and counter-currenthad passed under the ship with a great deal of turbulentwater and opposite current flow on either side of the line

of convergence. After the current stabilized, positioningwas returned to auto with no further problems on thissite.

Positioning on Site 317 was in auto with the exceptionof about 15 min in semi-auto when failure of the pitchgyro amplifier caused the main shafts to be commandedfull astern from 100 rpm ahead. The amplifier wasreplaced and the system returned to auto for the dura-tion. Positioning was excellent for the remainder of theleg with no further problems of any kind.

EXPLANATORY NOTES

Organization and Subdivision of the ReportThis Initial Report volume is divided into three parts.

Part I consists of an Introduction and ExplanatoryNotes chapter and Site Reports based mostly on thework accomplished during shipboard studies at sea. PartII, Special Studies, contains chapters on paleontology,geochemistry, petrology, mineralogy, and geophysicswhich were written by members of the shipboard partyor interested specialists both within and without theDeep Sea Drilling Project. The chapters in Part II in-clude interpretations based on information that wasavailable at the time the chapters were submitted. PartIII consists of chapters dealing with regional geology,stratigraphy, and sedimentology which were written bythe shipboard scientists.

Material in the Site Report chapters is arranged in astandardized order as follows (authorship of varioussections within the Site Reports is indicated inparentheses):

Site Data: Location, dates occupied, position, waterdepth, total penetration, number of cores taken, totallength of recovery, deepest unit recovered, and principalresults (Jackson and Schlanger).

Background and Objectives: Reason for drilling,geophysical data, presite surveys, description ofavailable data, and objectives (Winterer, Schlanger, andJackson).

Operations: Site approach and profiler records,Sonobuoy surveys, drilling and coring program, drilling

14


TABLE 5Deep Sea Drilling Project Beacon Summary, Leg 33

Site

314315315A316316317317A317B318

Make

OREOREOREOREOREOREOREOREORE

Freq.(kHz)

16.016.016.013.516.016.016.016.013.5

SerialNumber

242260260209248257257257286

Site Time(hr)

42.532.0

124.59.5

105.526.589.567.077.0

Very strong signalVery strong signalVery strong signalSignal dropped byVery good signalVery good signalVery good signalVery good signalGood signal

Remarks

— long life— long life25 db — dropped replacement

operations, and coring summary (Schlanger andJackson).

Lithology: Description of column starting at the top(basalt section by Jackson), stratigraphic column, barrelsheets, lithologic summary (Cook, Kelts, Jenkyns,Winterer).

Physical Properties: Density, porosity, sonic velocity(Boyce).

Geochemistry: CaCoi "bomb" (Dootson).Biostratigraphy: Calcareous nannoplankton (Mar-

tini), foraminifera (McNulty and Kaneps), Radiolaria(Johnson).

Sedimentation Rates: (Kaneps, Schlanger, Jackson).Correlation of Seismic Reflection Profiles With Drill-

ing Results: (Winterer and Schlanger).Summary and Conclusions: (Jackson and Schlanger).References: Includes references for entire Site Report.Data presentations given for each site chapter include:1) Core forms with detailed presentations of the

lithology, physical properties, and biostratigraphy ofeach core recovered (Winterer, Cook, Kelts, Jenkyns,Kaneps, Johnson, Martini, Boyce). Symbols used onthese forms are explained in another section of thischapter (Conventions and Symbols).

2) Physical properties graphic log with a plot of den-sity, porosity, and sonic velocity.

3) Core photographs (black and white) are arrangedin order by hole, core, and section.

Survey and Drilling Data

The survey data used in precruise planning for specificsite selections are given in each Site Report chapter. Wedepended heavily on records obtained from the Lamont-Doherty Geological Observatory (Columbia Univer-sity), Scripps Institution of Oceanography (UC SanDiego), and the Hawaii Institute of Geophysics (Univer-sity of Hawaii). Short surveys were made by GlomarChallenger before dropping the beacon. We found ex-cellent correspondence between profiles from the aboveinstitutions and Glomar Challenger records.

Steaming between sites, continuous observations weremade of water depth, the magnetic field, and subbottomstratigraphy and structure. Underway depths wererecorded on a Gifft precision depth recorder; the depthswere read on the basis of an assumed 800 fathoms/secsounding velocity. The sea depth (in m) at each site sub-sequently was corrected (1) according to the tables of

Matthews (1939) and (2) for the depth of the hull trans-ducer (6 m) below sea level. In addition, any depthsreferred to the drilling platform were calculated underthe assumption that this level is 10 meters above thewater line.

The magnetic data were collected with a Varian pro-ton magnetomater with the sensor towed 300 metersbehind the ship. The readings, for shipboard use, weretaken from an analog recorder every 5 min.

The seismic profiling system consisted of two Bolt air-guns, a Scripps-designed hydrophone array, Bolt ampli-fiers, two bandpass filters, and two EDO recorders(filter settings, airgun sizes, etc., are shown on the in-dividual profiles).

Basis for Numbering Sites, Cores, SectionsEach drilling site accomplished by DSDP is assigned a

number, for example, Site 314. The first hole at each sitecarries the site number, i.e., Hole 314; additional holesat the same site have a letter following the number. Forexample, Hole 317A is the second hole drilled at Site 317and Hole 317B would have been the third hole drilled atthis site.

The cores from each hole are numbered successivelyin the order in which they were taken: Core 1, Core 2,etc. A core was taken by dropping a core barrel downthe drill string, and coring for 9 meters as measured bythe lowering of the drill string. Sediments were retainedin a plastic liner about 9.3 meters long inside the corebarrel and in a 0.40-meter-long core catcher assemblybelow the liner. Generally, the liner was not completelyfull.

When the core barrel was recovered on deck, the corecatcher was removed from the barrel, and any materialin the catcher (as much as 25 cm in length) was labeled"core catcher," or CC. The plastic core liner waswithdrawn from the steel barrel and cut into 150-cmlengths called sections, beginning at the lower end of thebarrel. A liner (average length about 9.3 m) can be cutinto six such sections, with a short section about 30 cmin length left over at the top end. The numbering schemefor the sections depends on how much material isrecovered. In a full barrel, the short top section is calledthe "zero" section, and the first 150-cm section belowthat is Section 1, the next, Section 2, etc. When thebarrel is only partly filled, the cutting of the plastic linerproceeds as usual, starting from the bottom of the liner.

15


> HEADING AVERAGE

WIND: DIRECTION ANDSPEED (MPH) - AVERAGE

SWELL: DIRECTION ANDHEIGHT (FEET) - AVERAGE

CURRENT: DIRECTIONAND SPEED (KTS.)

THRUSTER AVERAGE RPM

#314

#315 #317

22

Completely averagedpositioning variable

#316 #318

Wind changed from 130° to 040° duringhole, heading from 100° to 028°,current assumed only no charted current

Figure 5. Summary of dynamic positioning at Leg 33 sites.

16


The labeling, however, begins with the uppermost 150-cm section in which there is core material. That section,even if only partly full, is Section 1; the next below isSection 2, etc. The following diagram illustrates the twocases.

FullBarrel

PartlyFull

Bottomi

H h

Top

H 1 1 1-

CC 6 5 4 3 2 1 0

H 1 1-

CC 4 3 2 1

Within each section, individual samples or obser-vations are located in centimeters down from the top ofthe section. This is true even when a section is not full ofmaterial, either because of original lack of material (ashort Section 1, for example), or because of voidsproduced by compaction or shrinkage.

To designate a sample, a shorthand numbering systemis used. Briefly, a sample designated as 317-15-2, 50-52cm is from the 50-52 cm interval below the top of Sec-tion 2, in Core 15 of Hole 317, that was drilled duringLeg 33. Generally, the leg number is left off the sampledesignations.

Sometimes the core barrel will jam up with hard sedi-ment after coring a few meters; the core will then reallyrepresent only the first few meters penetrated. At othertimes, the circulation of water may wash away the uppersofter part of a core and recovery will represent thelower part. Separated lengths of core in a core liner maycome from the drill bit being lifted away from the bot-tom of the hole during coring in rough sea conditions.Similarly, there is no guarantee that the core-catchersample represents the material at the base of the coredinterval. The labeling of samples is therefore rigorouslytied to the position of the sediment or rock within a sec-tion as the position appears when the section is first cutopen and is logged in the visual core description sheets.

Handling of Cores

The first assessment and age determination of the corematerial was made on samples from the core catcher assoon as possible after the core was brought on deck.After a core-section had been cut, sealed, and labeled, itwas brought into the core laboratory for processing. Thecore-section was first weighed for mean bulk densitymeasurement. Then GRAPE (Gamma Ray AttenuationPorosity Evlaution) analysis was made for detailed den-sity determinations.

After the physical measurements were made, the coreliner was cut on a jig using Exacto-type blades and theend caps cut by knife. The core was then split with acheese cutter if the sediment was soft. When compactedor partially lithified sediments were included, the corehad to be split by a band saw or diamond saw.

One of the split halves was designated a "working"half. Sonic velocity determinations using a Hamiltonframe were made on pieces from this half. Numeroussamples were measured both parallel and perpendicularto bedding as part of a seismic anisotropy study. Sam-ples, including those for grain size, X-ray mineralogy,

interstitial water chemistry, and total carbonate content,were taken, labeled, and sealed. The working half wasthen sent to the paleontology laboratory. There, samplesfor shipboard and shore-based studies of nan-noplankton, foraminifera, and radiolarians were taken.

The other half of a split section was designated an"archive" half. The cut surface was smoothed with aspatula to bring out more clearly the sedimentaryfeatures. The color, texture, structure, and compositionof the various lithologic units within a section weredescribed on standard visual core description sheets(one per section) and any unusual features noted. Smearslides were made and examined with a petrographicmicroscope. The archive half of the core-section wasthen photographed. Both halves were sent to coldstorage onboard after they had been processed.

Material obtained from the core catcher and not usedup in the initial examination was retained in freezer box-es for subsequent work. Hand sediments were handledas follows:

Pieces were removed from the core catcher and placedin short piece of the half liner, maintaining proper se-quence and orientation. These pieces were placed in thebottom of the liner of the lowest section recovered, andthe entire core moved upward by the length of the core-catcher material. Pieces were labeled on the outside ofthe core with an arrow pointing up and provisionalnumber to maintain sequence. Core-catcher materialwas split on a diamond saw, making certain each piecehad a label. Core material recovered in the core linerwas labeled and split; when split pieces were replaced inhalf-liners, room was left at the bottom of the lowestsection for core-catcher material, and other piecesmoved up accordingly. From this point on, the core ishandled as any other sediment core.

All sediment samples from Leg 33 are now depositedin cold storage at the DSDP West Coast Repository atthe Scripps Institution of Oceanography, La Jolla,California.

Visual core descriptions of igneous rocks, includingbasalts, were simply continued on the visual coredescription sheets, rather than placed on a separateform, as has been done heretofore. Color index, rocktype, textures, percent of phenocrysts, percent and sizeof vesicles, structures, and alteration were routinelynoted. The sampling procedure for basalts was differentfrom that of sedimentary rocks in that oriented 1-in.plugs were drilled from sections in the round. In generalone plug was cut from each flow unit in the two holeswhere basalt was cored, and thin sections were madeaboard ship for confirmatory descriptions. Thin sectionsof igneous rocks were described on the visual coredescriptions of the igneous rocks form. In general, thenames of igneous rocks are based on the textural andmineral proportion data of Macdonald and Katsura(1964) where rocks were not so altered as to precludeidentification.

The basalt samples are stored in a dry, nonre-frigerated container.

Drilling DisturbancesWhen the cores were split, many of them showed signs

of postdepositional disturbance. Such signs were the

17


concave downwards appearance of originally planebands, the haphazard mixing of lumps of differentlithologies, and the near-fluid state of some sediments.

During drilling, six basic parameters (bit type, weighton the bit, pipe revolutions per minute, torque, pumppressure, and pump strokes per minute) reflect the con-ditions at the contact between bit and sediment. When acore is being cut, water circulation is reduced to aminimum, or zero, and bit weight is normally kept tolower values and increased more steadily than duringdrilling. Invariably, however, some short periods of cir-culation are required, and it is then that softer sedimentsmay be washed away from the bit or that water may beforced up inside the core liner, turning the sediment intoa slurry. The washing away of softer sediment duringperiods of circulation can lead to the recovered cores be-ing unrepresentative samples of the drilled strata. This isespecially true when alternating hard and soft beds arecut. The heave of the bit while coring during roughweather may also lead to fluid cores.

Four degrees of drilling deformation were recognizedin the sediments as follows: (a) slightly deformed, (b)moderately deformed, (c) highly deformed, and (d)soupy. The criteria used in defining these degrees ofdeformation was that slightly deformed sediments ex-hibit a small bending of bedding contacts, whereas ex-treme bending defines moderate deformation. Forhighly deformed strata, bedding is completely disruptedand/or at times has vertical attitudes. Soupy intervalsusually are water saturated and lose practically allaspects of bedding. In intervals of alternating hard andsoft beds, such deformation will be characterized bybrecciated fragments of the former, surrounded byviscous to soupy flowage of the latter.

Physical Properties

A thorough discussion of physical properties ispresented by Boyce (this volume). It covers equipment,methods, errors, correction factors, presentation, andcoring disturbance relative to the validity of the data.Only a brief review is given here.

The physical properties are presented in graphicalform and discussed in each site chapter. Some explana-tion of the measuring techniques and data processingfollows.

1) Sediment water content (W): The water content(W) is defined as the weight of water in the sedimentdivided by the weight of the saturated wet sediment. Theformer is obtained by heating a 0.5-ml cylindrical sam-ple (taken with a syringe) to about 110°C for 24 hr andweighing the sample before and after heating. The watercontent (%) is thus:

W =

100 (weight of wet sediment-weight of dry sediment + salts)

weight of wet sediment

No corrections were made for the salts, but the valuesare thought to be accurate to within ±3%.

2) Sediment porosity (0): The porosity (0) is definedas the volume of pore space divided by the volume of thewet saturated sample and is expressed as a percentage.

Porosities calculated from W are not plotted. The con-tinuous plots of porosity (site summaries only) are ob-tained from the GRAPE densities (see below) assuminga mean grain density of 2.67 g/cm3 and a water densityof 1.024 g/cm3.

3) Wet bulk density (p): The wet bulk density (p) isdefined as the weight in grams per cubic centimeter ofthe wet saturated sediment, i.e.:

P =weight of wet sediment

volume of wet sediment (cm3)

The densities of the seawater-saturated cores weremeasured in three ways: (1) by weighing each 1.5-metercore-section, giving a mean density for the whole sec-tion; (2) from the water content W (syringe samples);and (3) by continuous measurement along the length ofthe core-section with the GRAPE using as standards,water (1.024 g/cm3) and aluminum (2.6 g/cm3). It isnoted that because of the possible presence of drillingdisturbances, low values are suspect and emphasisshould be placed on the maximum densities (minimumporosities).

4) Compressional wave velocity (Vp): The sonicvelocity (Vp) is obtained by timing a 400-kHz sonicpulse across two transducers and measuring the distanceacross the sample with a dial gauge (Hamilton framemethod). Measurements were made at laboratory tem-perature and pressure, a time delay of about 4 hr beingallowed for the cores to reach equilibrium.

5) Specific acoustic impedance (Zp): This is definedas density multiplied by compressional wave velocity.The parameter is of value in the interpretation of seismicreflection profiles.

Shore-Based Studies

Grain-Size AnalysesGrain-size distribution was determined by standard

sieving and pipette analysis. The sediment sample wasdried and then dispersed in a Calgon solution. If thesediment failed to disaggregate in Calgon, it was dispersedin hydrogen peroxide. The sand-sized fraction wasseparated by a 62.5 µm sieve, with the fines beingprocessed by standard pipette analysis following Stokessettling velocity equation, which is discussed in detail inVolume IX of the Initial Reports of the Deep Sea Drill-ing Project. Step-by-step procedures are covered inVolume IV. In general, the sand-, silt-, and clay-sizedfractions are reproducible within ±2.5% (absolute) withmultiple operators over a long period of time. A discus-sion of this precision is in Volume IX.

Carbon and Carbonate AnalysesThe carbon-carbonate data were determined by a

Leco induction furnace combined with a Leco acid-basesemiautomatic carbon determinator. Normally, themore precise seventy-second analyzer is used in place ofthe semi-automatic carbon determinator.

The sample was burned at 1600°C, and the liberatedgas of carbon dioxide and oxygen was volumetricallymeasured in a solution of dilute sulfuric acid and methyl

18


red. This gas was then passed through a potassiumhydroxide solution, which preferentially absorbs carbondioxide, and the volume of the gas was measured a sec-ond time. The volume of carbon dioxide gas is thedifference of the two volumetric measurements. Correc-tions were made to standard temperature and pressure.Step-by-step procedures are in Volume IV of the InitialReports of the Deep Sea Drilling Project and a discus-sion of the method, calibration, and precision are inVolume IX.

Total carbon and organic carbon (carbon remainingafter treatment with hydrochloric acid) are determinedin terms of percent by weight and the theoretical percen-tage of calcium carbonate is calculated from the follow-ing relationship:

Percent calcium carbonate (CaCC>3) =(%total C -%C after acidification) X8.33

However, carbonate sediments may also include mag-nesium, iron, or other carbonates; this may result in"calcium" carbonate values greater than the actual con-tent of calcium carbonate. In our determinations, allcarbonate is assumed to be calcium carbonate. Precisionof the determination is as follows:

Total carbon(within 1.2%-12%)

Total carbon(within 0%-l. 2%)

Organic carbon =Calcium carbonate (within =

10%-100%)(within 0%-10%)

= ±0.3% absolute

±0.06% absolute±0.06% absolute±3% absolute

= ± 1 % absolute

X-Ray MethodsSamples of sediment were examined using X-ray dif-

fraction methods at the University of California atRiverside, under the supervision of H.E. Cook.

Treatment of the raw samples included washing toremove sea water salts, grinding to less than 10 µm underbutanol, and expansion of montmorillonite with trihex-ylamine acetate. The sediments were X-rayed as ran-domized powders. A more complete account of themethods used at Riverside is found in Appendix III ofVolume IV of the Initial Reports.

Rules for Naming Common Pelagic Sediments

Nomenclature proposal for Leg 33Rule 1. The word order for names is:

color - constituent(s) - indurationmodifier(s)

Rule 2. Color is determined using GSA color chartnames followed by color code number in(parentheses).

Rule 3. A constituent should be >5% to be includedin a name.

Rule 4. Only two constituents appear in a name.Rule 5. Ranges used for smear-slide descriptions are:

<5% rare(R)5%-25% common (C)

25%-50% abundant (A)>50% dominant (D)

Rule 6.1 If (A) is >75%: called clay with a precedingconstituent modifier; if (A) <75% calledooze with appropriate constituent modifiersdiscussed below.

Rule 7. If any single biogenous constituent is domi-nant (D); that constituent is used as lastmodifier in name.

Rule 8.1 If no constituent is >50% then(a) Σ (B) biogenous siliceous constituent

> Σ (C) calcareous constituents calledsiliceous ooze.

(b) Σ © > Σ @: called calcareousooze. Second most abundant consti-tuent used as the first modifier.

Clay mineralszeolitic brownAmorph. KRAPAuthigenics

26%

Biogenous Siθ2(K+d+Sfm)

50%Biogenous CaCθ3(F+n+undefined)

Rule 9. Induration rule chart

Constituents

ö tβ»-" D C3 " ^

§ ë |

Calcareous Siliceous

oozefirm oozechalklimestone

oozefirm oozeporcellanitechert

clay

claystone

Rule 10. Unusual or nonpelagic sediments not coveredby the above classification are to be named ina (geologically) logical manner.

Hypothetical sediments—without color designation:

30% Forams40% Rads20% Nannos10% Clay

—^RadiolarianCalcareous Ooze

60% Forams20% Rads10% Zeolitic clay10% Nannos

^RadiolarianForaminiferal Ooze

'Rules 6 and 8 pertain to the construction of a triangulardiagram.

19


60% Clay 75% Zeolitic clay40% Rads 20% Rads

Clayey 5% NannosRadiolarian Ooze —>Radiolarian

Zeolitic ClayGraphic symbols for lithology as used on core and site

logs are shown in Figure 6.

Basis for Age Determination

The integrated biostratigraphic framework forforaminifers, nannofossils, and radiolarians as used onLeg 33 is shown in Figure 7. A scale of absolute age,based on that of Berggren (1972) for the Cenozoic andDSDP Leg 17 (Winterer, 1973) for the Cretaceous, isalso given.

The planktonic foraminifer zonation for mid-Eoceneand younger sediments is that of Blow (1969) with theexception of the Oligocene and Pleistocene. For theOligocene, the zonation of Bolli (1970) was found to bemore suitable, and the Pleistocene was subdivided intotwo zones on the basis of the extinction horizon ofGloboquadrina pseudofoliata Parker, which has been es-timated by Thompson and Saito (1974) to have an age ofabout 220,000 yr. For pre-mid-Eocene sediments thezonation of Blow and Berggren (Berggren, 1972) wasused. In the Cretaceous, relatively few planktonicforaminifer zones could be recognized. Those for theUpper Cretaceous follow the definitions of Cita andGartner (1971), while those for the Lower Cretaceousare as defined by van Hinte (1971).

For Cenozoic nannofossils, the standard zonation(Martini, 1971), as emended by Martini (this volume),was used. In the Cretaceous, a composite system ofzones by various authors was employed (see Martini,this volume).

The radiolarian zones recognized are those of San-filippo and Riedel (1973) and Foreman (1973a) for theupper Paleocene and lower Eocene; those of Riedel andSanfilippo (1970), as modified by Foreman (1973b), forthe middle and upper Eocene; those of Riedel and San-filippo (1971) for the Oligocene through Pliocene; andthose of Nigrini (1971) for the Quaternary.

In addition, reference is made to the chapters in thisvolume by Martini (silicoflagellates), Takayanagi andOda (Cenozoic foraminifers), Beckmann (large foram-inifers), Schrader (diatoms), Bukry (nannofossils), andKauffman (mollusks) for additional data on the age ofsediments recovered during Leg 33.

REFERENCESBargar, K.E. and Jackson, E.D., 1974. Volumes of individual

shield volcanoes along the Hawaiian-Emperor Chains:U.S. Geol. Surv. J. Res., v. 2, p. 545-550.

Bass, M.N., Moberly, R.M., Rhodes, J.M., Shih, C.-y.,Church, S.E., 1973. Volcanic rocks cored in the CentralPacific, Leg 17, Deep Sea Drilling Project. In Winterer,E.L., Ewing, J.I., et ah, Initial Reports of the Deep SeaDrilling Project, Volume 17: Washington (U.S. Govern-ment Printing Office), p. 429-504.

Berggren, W.A., 1972. A Cenozoic time scale—some im-plications for regional geology and paleobiogeography:Lethaia, v. 5, p. 195-215.

Blow, W.H., 1969. Clavatorella, a new genus of the Globo-rotaliidae: Micropaleontology, v. 11, p. 365-368.

Bolli, H.M., 1970. Planktonic foraminifera from the Oligo-cene-Miocene Cipero and Lengua formations of Trinidad,B.W.I.: U.S. Natl. Mus. Bull. 215, p. 97-123.

Cita, M.B. and Gartner, S., 1971. Deep sea Upper Cretaceousfrom the Western North Atlantic: Plankt. Conf. Second,Rome, 1970, Proc, Faunacci, A. (Ed.), Roma (Tecnoscien-za), p. 287-319.

Clague, D.A. and Dalrymple, 1973. Age of Koko Seamount,Emperor seamount Chain: Earth Planet. Sci. Lett., v. 17, p.411-415.

Clague, D.A. and Jarrard, R.D., 1973a. Hot spots and Pacificplate motion: EOS (Am. Geophys. Union Trans.), v. 54, p.238.

, 1973b. Tertiary Pacific plate motion deduced fromthe Hawaiian-Emperor Chain: Geol. Soc. Am. Bull., v. 84,p. 1135-1154.

Coplen, T. and Schlanger, S.O., 1973. Oxygen and carbonisotope studies of carbonate sediments from Site 167,Magellan Rise, Leg 17, Deep Sea Drilling Project. InWinterer, E.L., Ewing, J.I., et ah, Initial Reports of theDeep Sea Drilling Project, Volume 17: Washington (U.S.Government Printing Office), p. 505-510.

Foreman, H.P., 1973a. Radiolaria of Leg 10 with systematicsand ranges for the Families Amphypyndacidae, Ar-tostrobiidae, and Theoperidae. In Worzel, J.L., Bryant, W.,et ah, Initial Reports of the Deep Sea Drilling Project,Volume 10: Washington (U.S. Government Printing Of-fice), p. 407-474.

, 1973b. Radiolaria from DSDP Leg 20. In Heezen,B.C., MacGregor, I.D., et ah, Initial Reports of the DeepSea Drilling Project, Volume 20: Washington (U.S.Government Printing Office), p. 249-306.

Jackson, E.D., Silver, E.A., and Dalrymple, G.B., 1972.Hawaiian-Emperor Chain and its relation to Cenozoic cir-cumpacific tectonics: Geol. Soc. Am. Bull., v. 83, p. 601-617.

Macdonald, G.A. and Katsuia, T., 1964. Chemical composi-tion of Hawaiian lavas: J. Petrol., v. 5, p. 82-133.

Martini, E., 1971. Standard Tertiary and Quaternarycalcareous nannoplankton from the Western EquatorialPacific. In Winterer, E.L., Riedel, W.R., et ah, InitialReports of the Deep Sea Drilling Project, Volume 7:Washington (U.S. Government Printing Office), p. 1471-1507.

Matthews, D.J., 1939. Tables of the velocity of sound in purewater and in seawater: Hydrographic Department, Ad-miralty, London.

Morgan, W.J., 1971. Convection plumes in the lower mantle:Nature, v. 230, p. 42-43.

, 1972a. Deep mantle convection plumes and platemotions: Am. Assoc. Petrol. Geol. Bull., v. 56, p. 203-213.

., 1972b. Plate motions and deep mantle convection:Geol. Soc. Am. Mem., v. 132, p. 7-22.

Nigrini, C.A., 1971. Radiolarian Zones in the Quaternary ofthe Equatorial Pacific Ocean. In Funnell, B.M. and Riedel,W.R. (Eds.), The micropaleontology of oceans: Cambridge(Cambridge University Press), p. 443-461.

Riedel, W.R. and Sanfilippo, A., 1970. Radiolaria. In Bader,R.G., Gerard, R.D., et ah, Initial Reports of the Deep SeaDrilling Project, Volume 4: Washington (U.S. GovernmentPrinting Office), 503-575.

, 1971. Cenozoic Radiolaria from the westerntropical Pacific, Deep Sea Drilling Project, Leg VII. InWinterer, E.L., Riedel, W.R., et ah, Initial Reports of theDeep Sea Drilling Project, Volume 7: Washington (U.S.Government Printing Office), p. 1529-1694.

20


Nannofossilooze

Foram-nannochalk

1

1I

1,

1 'T |i 'I 1

i

' 1I I

iT1TI

t

I1f111I

Clayeylimestone

Sandy clay

Claystone

Nanno-foramooze

Limestone

I

I,. 1r__.

i i

i i

i i

i i

1 I ' i

i

ii

Rad ooze

Silty clay

Volcaniclastic sand-,silt-, and claystones

Nannochalk

_L_ I XI I

j I

Dolomiticlimestone

rrrnππi

\Pyritic-nannospicular ooze

Sandy-siItyclay

Chert

A A AA A AA A A

A A A

Foramchalk

Sandy-gradedlimestone

f I f j 1; i : i ;

• i » i «» y •

• » ' T

: I : I : IT : I :

Zeoliticclay

Sand

Basalt

R = RadsD = DiatomsF = ForamsZ = Zeolites•Fe = FerruginousV = VolcanicC = Clay

Figure 6. Graphic lithological symbols employed on core and site logs, Leg 33.

21


STAGE

Calabrian

Astian ^ ^

^ ^ ^ Piacenzian

Tabianian

Messinian

Serravallian

Langhian

Burdigalian

Aquitanian

Chattian

Rupelian

Lattorfian

Priabonian

Bartonian

Lutetian

Thanetian

Danian

SERIES

a

j

wS

i

aQ

X

3

atu

s

waa£

1

w

aQai

oüw

2

02J-

1

a.

zos

tü

zsuo

u

zJ-q

zEdyow<a.

ZONE

FORAMINIFERS

N.21

N.19

N.17

N.16

N.15

N.14

N.13

N..12

N.10N.9N.8N.7

N.6

N.5

ZOH<

U

Q

Z

P.16

P. 14

P.13

P.12

PI 1

P.10

P.9

P.8

P. 7

P.5

P.4

P.3

P. 2

P.I

G. conglomerαtα

G. pseudofoliαtα

G. tosαensis

G. tumidα/S. dehiscens

G. plesiotumidα

G. αcostαensis

G. menαrdii

G. nepentheslG. sαikensis

S. sitbdehisceπs/G. dritryi

G. fohsi s.l.

O. suturαlisG. hispliericus/G. insuetα

G. insuetαlG. trilobus

G. insuetα/C. dissimilis

G. trilohus

G. kugleri

G. primordius

G. ciperoensis

G. opimα

G. αmpliαperturα

C. chipolensis/P. hαrhαd<H•nsis

G. cerroαzulensis

T. rohri

O. beckmαnni

G. lehneri

G. kugleri

H. αrαgonensis

A. dense

G. αrαgonensis

G. formosα

b

a

G. subbotinαe/A. wilcoxensis

G velαscoensis/G subbotinαe

G. velαscoensis

G. pseudomenαrdii

G. pusillα/G. αngulαtα

G. uncinαtα/G. spirαlis

G. triloculinoides

G. pseudobulloides

AGE(m.y.)

- -

- -

- 15 -

- -

- 2 0 -

-

— 25 -

- -

- 40 -

- "

- 45 -

- -

- -

NANNOFOSSILS

INN20

NN19

NN1R

NN16.NN15NN13NN12

N N U

NN10

NN9

NN7

NN6

NN5

NN4

NN2

NN1

NP25

NP24

NP23

NP22

NP21

NP20

NP19

NP18

NP17

NP16

NP15

NP14

NP13

NP12

NP11

NP10

NP9

NP8

NP7

NP6

NP5

NP4

NP3

NP2

NP1

E. huxleyi G o c c m i c α

P. lαcunosα

D. brouweri

... D. surculus_ A. psi.uJou)iibihi.d ^ πnvtnetricus—

C rugosus

D. quinquerαmus

D. cαlcαris

D. hαmαtus

—K-,—r-. C. coαlitusD. kugleri

D exilis

S. heteromorphus

Helicopontosphαerα reticulαtα

D. dniggi

T • I-'

5. ciperoensis

S. disti•>m<s

S. pn•Jisreiitus

H. reticulαtα

h\ suhdisticliα

S. pseudorαdiαns

Isthmolitlius reα<n>us

ü. sαipαnensis

D. tαni nodifer

ChiphrαgmαlUhus αlαtus

D. sublodoensis

D. lodoensis

Mαrthαsterites tribrαchiαtus

D. binodosus

M cnnlortus

D. multirαdiαtus

Heliolithus riedeli

D. gemmeus

H. kleinpelli

h'αsciculithus tympαniformis

Ellipsolithus mαcellus

Chiαsmolithus dαnicus

Lruciplαcolithus tenuis

Mαrkαlius inversus

AGE(m.y.)

-

- 10 -

- 15 -

- -

- 20 -

-

- 25 -

- -

- 40 -

- -

- 45 -

-

- 60 -

- -

RADIOLARIANS

Pterocαnium prismαtium

Spongαster pentαs

Stichocorys peregrinα

Ommαtαrtus penultimus

Ommαtαrtus antepenultimus

Cannartus petterssoni

Cannartus laticonus

Dorcadospyris alata

Calocycletta costata

Calocycletta virginis

l.ychnocanoma elongata

Dorcadospyris ateuchus

Tlieocyrtis tuberosa

Thyrsocrytis hromia

Podocyrtis goetheana

Podocyrtis chalara

, Podocyrtis ampla

Theocampe mongolfieri

T rryplnrpphπlπ rrvptorephnln

Buryella clinata

Bekoma bidarfensis

UNZONED

Figure 7. Biostratigraphic framework and time scale used during Leg 33 (see text for explanation).

22

* A

GE

(m.y

.)

7 0 -

7 5 -

80-

8 5 -

9 0 -

9 5 -

inn -

105-

110-

115-

SER

1ES

in

<

ËoüuBi

OHOH

owU<cHW

u

o

STA

GE

Z<H

HW<

z<z<(X.|

u

<zCΛ Q

H

Λ Z

zOu

u<z°z

siH

z<z<o

u

z<5<

z<

<

z

wOS

Dü

n

ZONES

NANNOFOSSILS

Tetralithus murus

Lithraphiditesquadratus

Arkhangelskiellacymbiformis

Tetralithus trifidus

Tetralithus gothicus

Tetralithus aculeus

Marthastehtes furcatus(base undefined)

NOTZONED

FORAMINIFERS

Globotruncana qansseri

Globotruncana calcarata

Globotruncana elevata

NOPLANKTONIC

FORAMINIFERS

Glob igerinelloidesalgerianus

Leupoldina cabri

Figure 7. (Continued).

23



Salisbury, M.N. and Christensen, N.I., 1972. Velocity-densitysystematics for JOIDES basalts (abstract): Geol. Soc. Am.,Abstracts with Programs, v. 4, p. 228.

Sanfilippo, A., and Riedel, W.R., 1973. Cenozoic Radiolaria(exclusive of theoperids, artostrobiids and amphypyn-dacids) from the Gulf of Mexico, Deep Sea Drilling Proj-ect, Leg 10. In Worzel, J.L., Bryant, W., et al., InitialReports of the Deep Sea Drilling Project, Volume 10:Washington (U.S. Government Printing Office), p. 475-611.

Schlanger, S.O., 1963. Subsurface geology of Eniwetok atoll:U.S. Geol. Surv., Prod. Paper, 260-B4, p. 74.

, 1965. Dolomite-Evaporite Relations on PacificIslands: Sci. Rept., Tohoku Univ., Japan, v. 37, p. 15-29.

Schlanger, S.O. and Tracey, J.I., Jr., 1970. Dolomitizationrelated to Recent emergence of Jarvis Island, Southern LineIslands (Pacific Ocean): Geol. Soc. Am. Bull., v. 2, p. 676.

Scholl, D.W., Creager, J.S., Boyce, R.E., Echols, R.J.,Fullam, T.J., Graw, J. A., Qoizumi, I., Lee, H., Ling, H.Y.,

Supko, P.R., Stuart, R.J., and Worsley, T.R., 1971. DeepSea Drilling Project Leg 19: Geotimes, v. 16, p. 12-15.

Shaw, H.R., 1973. Mantle convection and volcanic periodicityin the Pacific: Evidence from Hawaii: Geol. Soc. Am. Bull.,v. 84, p. 1505-1526.

Shaw, H.R. and Jackson, E.D., 1973. Mantle convection andvolcanic periodicity in the Pacific: Result of thermal plumesor gravitational anchors?: J. Geophys. Res., v. 78, p. 8634-8652.

Thompson, P.R. and Saito, T., 1974. Pacific Pleistocene sedi-ments: planktonic foraminifera dissolution cycles andgeochronology: Geology, v. 31, p. 333-335.

van Hinte, J.E., 1971. The Cretaceous time scale andplanktonic foraminiferal Zones: Koninkl. Nederl. Akad.Weternscap Amsterdam Proc, Ser. V, v. 75, p. 61-68.

Winterer, E.L., 1973. Sedimentary facies and plate tectonics ofEquatorial Pacific: Am. Assoc. Petrol. Geol., v. 57, p. 265-282.

24

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