63. DIAGENETIC ALTERATION OF ORGANIC MATTER IN LEG 57 SEDIMENTS,DEEP SEA DRILLING PROJECT

Shunji Sato, Technology Research Center, Japan National Oil Corporation, Tokyo, Japan

ABSTRACTI analyzed Leg 57 sediments organogeochemically and spectro-

scopically. Organic carbon and extractable organic matter prevailfrom the Pliocene to the Miocene. Humic acids occur widely fromthe Pleistocene to the lower Miocene and one portion of the Oligo-cene. The absence of humic acids in Oligocene and Cretaceoussamples suggests that humic acids had changed to kerogen. Visiblespectroscopic data reveal that humic acids in this study have a lowdegree of condensed aromatic-ring system, which is a feature of an-aerobic conditions during deposition, and that chlorophyll deriva-tives that had at first combined with humic acids moved to the sol-vent-soluble fraction during diagenesis. The elemental compositionsof humic acids show high H/C and O/C ratios, which seem appro-priate to a stage before transformation to kerogen. The relation be-tween the linewidths and g-values on the electron spin resonance dataindicates that the free radicals in humic acids are quite different fromthose in kerogen. The low spin concentrations of kerogen and theyields of humic acids up to the lower Miocene demonstrate thatorganic matter in these sediments is immature. The foregoing in-dicate the necessity to isolate humic acids even in ancient rocks in thestudy of kerogen.

INTRODUCTION

Several DSDP samples contained humic acids (Nis-sembaum and Kaplan, 1972; Aizenshtat et al., 1973;Stuermer et al., 1978). Humic acids seem to convert tokerogen during diagenesis and katagenesis (Nissembaumand Kaplan, 1972; Welte, 1973). Recently, Stuermerand coworkers (1978) isolated humic acids and proto-kerogen (insoluble organic residue in unlithified sedi-ments) and reported the relation between two substances.However, few workers have studied the relation betweenhumic acids and kerogen by separating both materials.

In this study I isolated humic acids and kerogen fromthe sediments. In the category "kerogen" I include theprotokerogen, because the samples range from Recentsediments to ancient rocks.

The objective of this chapter is to evaluate thediagenetic alteration of organic matter from three sitesalong the Japan Trench transect through chemical andphysical analyses. The study methods include electronspin resonance (ESR) spectroscopy of humic acids andkerogen; visible spectroscopy and elemental analyses ofhumic acids; and organogeochemical measurements oforganic carbon and extractable organic matter.

Sites 438 and 439 are on the seaward edge of the deepsea terrace of the Japan Trench, and Site 440 is on theflat sea floor of the midslope terrace. The sedimentsfrom Sites 438 and 439 are terrigenous diatomaceousclaystone (Pleistocene to lower Miocene), turbidites andclaystone (base of lower Miocene), massive sandstone

and breccia-conglomerate (Oligocene), and black silici-fied claystone (Cretaceous). The sediments from Site440 are largely claystones (Pleistocene to upper "Mio-cene).

METHODS

Preparation and ExtractionI divided the dried and ground samples into two frac-

tions and provided a portion of one fraction (about 0.6g) for organic carbon analysis. I extracted the otherfraction for 80 hours in a Soxhlet apparatus with ben-zene:methanol 7:3; added copper to extracts in the boil-ing flask to remove sulfur; filtrated the extracts; andweighed the dried extracts as extractable organic matter.I treated the residue of the Soxhlet extraction for 10hours in a shaker with 0.1 N NaOH; centrifuged thealkaline suspension; acidified the supernatant solutionwith 6 N HC1; washed the resultant precipitates withdistilled water; and weighed the dried precipitates ashumic acids. I treated the centrifuged residue with 6 NHC1 and 48 per cent HF to remove carbonates and sili-cates; centrifuged the suspension; washed the resultantresidue with distilled water; and obtained kerogen.

Instrumentation

I measured the ESR spectra of humic acids and kero-gen on a JEOL electron spin resonance spectrometerPE-3X, employing a modulation frequency of 100 kHz

1305

S. SATO

and an operating frequency of about 9.4 GHz. I deter-mined the spin concentration with reference to that ofartificial coal with a known value (5.8 × 1014 spins); thelinewidth with reference to that of the Mn2+ markerfixed in the sample cavity; and the g-value with refer-ence to that of diphenylpicrylhydrazyl (g-value = 2.0036).Because kerogen in this preparation contained largeamounts of impurities, I expressed the value of the spinconcentration as the ratio to carbon of kerogen andhumic acids.

I observed the visible spectra of humic acids with 1mg in 10 ml of 0.1 TV NaOH solution on a Shimadzumultipurpose spectrometer MPS 5000.

According to the method of Heistand and Humphries(1976), I analyzed organic carbon in sediments by com-bustion at 460 °C for 13 minutes in an oxygen atmos-phere on a Perkin-Elmer 240 elemental analyzer. Forelemental analyses of humic acids and carbon analysisof kerogen for the ESR, I measured samples by combus-tion at 950 °C for 3 minutes in an oxygen atmosphere onthe same analyzer.

RESULTS AND DISCUSSIONTable 1 lists the organic carbon, extractable organic

matter, and humic acid content. Figure 1 illustrates thevariation of these values with depth.

The sediments in Sites 438 and 439 contain 0.35 to1.44 per cent organic carbon, 0.024 to 0.210 per cent ex-tractable organic matter, and 0 to 0.287 per cent humicacids. The Oligocene sediments contain small amountsof organic matter because these lithofacies are sand-stone and breccia-conglomerate. At Site 440, organiccarbon, extractable organic matter, and humic acid con-tent ranges from 0.50 to 2.21 per cent, 0.070 to 0.183per cent, and 0.062 to 0.875 per cent, respectively. Thevalues of organic carbon and extractable organic matterfrom the Pliocene to the lower Miocene samples in Sites438 and 439 and from all samples in Site 440 are almostidentical to those of the presumed source rocks from theNeogene Tertiary in the Japan Sea side, where we findthe majority of hydrocarbon accumulations in Japan.Organic carbon ranges from 0.86 to 2.04 per cent andextractable organic matter from 0.066 to 0.212 per centin the Akita and Niigata oilfields of the Japan Sea side(Yagishita, 1962; Kudo et al., 1965; Sato et al., 1972;Taguchi and Sasaki, 1973). Generally, organic carboncontent reflects organic richness, and a relation betweenorganic carbon and extractable organic matter (Figure2) can be a criterion for petroleum generation. Becausemost samples in this study include more than 0.5 percent organic carbon and more than 0.05 per cent ex-tractable organic matter, they are good prospects for oilformation.

Humic acids occur widely but are absent in the Oligo-cene (except for Sample 439-24-3) and Cretaceous sam-ples. This suggests that humic acids below the Oligocenehad changed to kerogen, as described by Nissembaumand Kaplan (1972) and Welte (1973). Samples from Site440 indicate higher amounts of organic carbon, extrac-table organic matter, and humic acids than those from

TABLE 1Organic Carbon, Extractable Organic Matter, and Humic Acid

Content in Sediments at Sites 438, 439, and 440

Sample

438-1-2438-5-3438-9-3438-11-3

438A-7-4438A-10-2438A-13-2438A-16-3438A-20-3438A-24-3438A-27-3438A-31-3438A-34-2438A-37-3438A-42-3438A-44-3438A-48-3438A-52-3438A-56-3438A-60-2438A-65-5438A-68-5438A-71-3438A-73-3438A-78-2438A-82-2438A-84-3

439-7-3439-11-3439-14-2439-18-3439-21-3439-22-3439-24-3439-26-3439-30-3439-38-1439-39-1

440-1-2440-5-5

440A-2-3440A-5-4440A-7-3

440B-4-3440B-7-3440B-11-3440B-14-5440B-18-2440B-21-3440B-24-3440B-31-3440B-35-3440B-39-3440B-43-3440B-47-1440B-51-1440B-54-3440B-58-2440B-61-1440B-66-3440B-71-1

Sub-bottomDepth(m)

3377694

122147175205243281309348375405452473520549587624676704729749795833853

872910934967996100410241044108111491154

242

87116134

172200239270303333362428466504542578616647683710-761806

OrganicCarbon(%)

0.680.521.011.21

1.211.441.191.290.800.820.700.951.061.150.550.841.100.720.610.880.910.680.480.771.040.590.81

0.790.750.790.580.540.360.660.400.350.440.51

1.291.54

1.150.870.91

1.380.940.952.211.890.931.000.780.811.260.681.010.670.840.920.880.500.63

ExtractableOrganicMatter(%)

0.0810.0590.1470.068

0.1010.1130.1220.1160.1020.1140.1420.0890.0890.0740.0920.0980.2100.1420.0760.0870.0890.0840.1060.1110.0670.0680.083

0.1420.1020.0720.1060.0840.0830.0520.0390.0240.0520.097

0.1060.183

0.1400.1050.160

0.1310.0810.1650.1050.0770.0860.0920.1080.1130.1360.0900.1340.1160.0700.1150.0660.0880.080

HumicAcids(%)

0.0700.1140.1160.059

0.2600.1930.1470.1020.0960.0570.1730.0380.0330.0730.0260.0720.0460.0420.1160.1270.0840.0950.2000.2870.1500.2620.088

0.1100.0740.0790.0500.02600.0220000

0.1460.223

0.2200.2000.875

0.0840.3030.8380.0720.3000.0670.2160.1510.0620.0660.0360.0760.0870.0630.1080.0760.0640.106

1306

DIAGENETIC ALTERATION OF ORGANIC MATTER

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Figure 1. Variations of organic carbon, extractable organic matter, and humic acids content with depth at Sites 438,439, and 440.

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Figure 2. Relationship between organic carbon and extractable organic matter at Sites 438, 439, and 440.

Sites 438 and 439, because at Site 440 fine sedimentswere deposited at a faster rate.

Most workers have neglected humic acids in ancientrocks because they believed that humic acids convertedto kerogen in the early stages of diagenesis. It is there-

fore important in this study to confirm that humic acidsoccur from the Pleistocene to the lower Miocene and inone of the Oligocene samples (439-24-3). Although thetransformation of humic acids to kerogen has not oc-curred in this area because of low heat flow (Uyeda,

1307

S. SATO

1972) and low thermal gradient, humic acid yields inancient rocks do provide significant clues for futurestudies of humic acids and kerogen.

Table 2 shows the ratio of extinction at 465 nm tothat at 665 nm (lvalue), peak height at 405 nm (//405)on visible spectroscopy, and elemental composition ofhumic acids. Figure 3 indicates the change of the £"-valueand the H405 value with depth.

The £"-value is lower with increased aromatic conden-sation of humic acids (Schnitzer and Skiner, 1969;Rashid and Vilks, 1975), and a low degree of condensedaromatic-ring system is a characteristic feature of humicacids developing in anaerobic environments (Rashid andVilks, 1975). The ^-values vary from 1.76 to 6.44 atSites 438 and 439 and from 4.70 to 6.32 at Site 440. Ex-cept for Sample 439-21-3, the sediments exhibit fairlyconstant ^-values between 4.22 and 6.44 which arehigher than the values between 3.7 and 4.7 determinedby Rashid and Vilks (1975). This suggests that humicacids in the present study contain a low degree ofaromatic condensation and that sedimentary depositionoccurred in anaerobic conditions. The lowest value ofSample 439-21-3 may indicate a transitional stage in thetransformation of humic acid to kerogen.

The 405-nm peak is the Soret peak of the chlorophyllderivatives and occurs commonly in marine humic sub-stances (Watanabe, 1972). //405-values range from 0 to0.074 at Sites 438 and 439 and from 0.022 to 0.186 atSite 440. The samples from Site 440 have higher //405-values than those from Sites 438 and 439, which indi-cates that at the former marine humic substances werepreserved.

As Figure 3 shows, /^-values decrease with depth,especially in Samples 438A-65-5 to 438A-82-2. Theseresults indicate that the chlorophyll derivatives movedfrom the humic fraction to the solvent-soluble fractionduring diagenesis.

The elemental composition of humic acids showshigh amounts of oxygen in comparison with that of coal(van Kleveln, 1961) and kerogen (Forsman and Hunt,1958; Forsman, 1963; Mclver, 1967; Tissot et al., 1974;Sato, 1976; Stuermer et al., 1978). The N/C atomicratios are fairly constant, but the others fluctuate withdepth.

Figure 4 indicates the relation between H/C and O/Catomic ratios of humic acids. The samples studied fall inpositions similar to those of Stuermer and coworkers(1978). The high H/C and O/C ratios in this study, aswell as the results of the E-values, may provide evidencefor the low degree of aromatic condensation of humicacids.

Table 3 lists the linewidth, g-value, and spin concen-tration on the ESR spectroscopy of humic acids and ker-ogen. Figure 5 shows the variation of ESR data withdepth.

Humic acids from Sites 438 and 439 show linewidthfrom 3.14 to 7.15 G, g-value from 2.00277 to 2.00359,and spin concentration from 0.19 × 1018 to 2.17 × 1018

spins/gC. At Site 440 humic acids range in linewidth

from 2.93 to 9.36 G, in g-value from 2.00283 to 2.00355,and in spin concentration from 0.18 × 1018 to 1.12 ×1018 spins/gC. The linewidth and g-value decrease grad-ually with increasing depth except for a rapid decreasein Samples 438A-71-3 to 438A-82-3. The spin concen-trations increase in Samples 438-1-2 to 438A-52-3, de-crease rapidly at the Sample 438A-52-3/438A-56-3 bound-ary; and then increase in Samples 438A-56-3 to 438A-84-3and from 439-7-3 to 439-21-3. The values of linewidthat Site 440 increase with depth, but g-values decrease inwide ranges except for Sample 440A-7-4. The spin con-centrations increase irregularly in Site 440.

The ESR signals of kerogen at Sites 438 and 439vary from 2.88 to 5.77 G in the linewidth, from 2.0027ito 2.00312 in g-value, and from 0.26 × 10

18 to 2.55 ×1018 spins/gC in the spin concentration. At Site 440 theyvary from 2.93 to 5.02 G in linewidth, from 2.00280 to2.00313 in g-value, and from 0.18 × 10

18 to 1.22 × 1018

spins/gC in the spin concentration. At Sites 438 and439, the linewidth and g-value of kerogen decrease withdepth; in Samples 438A-56-3 to 438A-82-2, linewidthdecreases rapidly. The spin concentrations of humic ac-ids change in a manner similar to that of kerogen. TheOligocene and Cretaceous kerogens have slightly highspin concentrations. The ESR signals of kerogen fromSite 440 increase dispersedly with depth. It is a char-acteristic feature of kerogen in this study to have lowerspin concentrations than that in the Japanese sourcerocks analyzed by Sato (1976) and by Morishima andMatsubayashi (1978). This indicates that organic matterin our study is still immature.

Figure 6 shows the relation between linewidths andg-values of humic acids and kerogens. It indicates aclose relation between linewidth and g-value, in contrastto the report by Stuermer and coworkers (1978), whofound no relation between them. In this study, kerogensfall in a quite different zone from humic acids; thekerogen zone is low both in linewidth and g-value incomparison with that of humic acids. This seems to bedue to the fact that kerogens and humic acids producedifferent types of free radicals: the free radicals inhumic acids are mainly semiquinone (Steelink, 1964;Ishiwatari et al., 1976), whereas in kerogen they aremainly pure aromatic. Therefore the ESR profiles ofhumic acids and kerogen exhibit different depth trends.Morishima and Matsubayashi (1978) reported thatg-values and linewidth of carbonaceous materials de-crease with increasing coalification or maturation. Inthis study, the fact that g-values and linewidth of humicacids are higher than those of kerogen suggests that hu-mic acids are the precursor of kerogens.

Since the report by Abelson (1967), who included in-soluble organic residue in Recent sediments in the term"kerogen," most workers have been measuring the ESRspectra of kerogen without separating out humic acids.Kerogen itself is the mixture of higher molecular com-pounds, and the composition of the precursor affectsthe ESR spectra, as pointed out by Sato (1976) and byMorishima and Matsubayashi (1978). Thus the results in

1308

DIAGENETIC ALTERATION OF ORGANIC MATTER

TABLE 2Visible Spectroscopy and Elemental Analyses of Humic Acids at Sites 438,439, and 440

Sample

438-1-2438-5-3438-9-3438-11-3438A-7-4438A-10-2438A-13-2438A-16-3438A-20-3438A-24-3438A-27-3438A-31-3438A-34-2438A-37-3438A-42-3438A-44-3438A-48-3438A-52-3438A-56-3438A-60-2438A-65-5438A-68-5438A-71-3438A-73-3438A-78-2438A-82-2438A-84-3439-7-3439-11-3439-14-2439-18-3439-21-3439-24-3440-1-2440-5-5440A-2-3440A-54440A-7-3440B-4-3440B-7-3440B-11-3440B-14-5440B-18-2440B-21-3440B-24-3440B-31-3440B-35-3440B-39-3440B-43-3440B-47-1440B-51-1440B-54-3440B-58-2440B-61-1440B-66-3440B-71-1

Sub-bottomDepth

(m)

3377694

122147175205243281309348375405452473520549587624676704729749795833853

872910934967996

10242

42

87116134

172200239270303333362428466504542578616647683710761806

VisibleSpectroscopy

E-Value

5.405.245.295.05

5.725.055.455.565.565.315.365.384.844.895.355.135.405.605.385.405.194.226.146.005.205.354.97

6.466.006.296.441.765.825.435.30

5.615.405.82

6.005.626.236.275.474.775.485.315.744.705.445.855.305.875.294.975.676.32

H405-Value

0.0610.0420.0740.032

0.0290.0290.0680.0560.0700.0700.0380.0690.0480.0530.0500.0540.0360.0380.0150.0110.0070.0010.0010.0010.0020.0020.019

0.0190.0280.001000

0.1440.056

0.0900.1860.022

0.1020.0540.0500.0650.1200.0800.0790.0900.0670.1140.0830.0590.0640.0550.0500.0490.0300.037

Ca

38.039.544.536.2

43.140.444.850.251.956.751.852.348.060.244.648.046.439.342.344.745.843.441.442.640.238.444.8

39.843.144.240.543.442.345.842.7

55.754.440.6

49.442.041.947.644.149.049.643.546.945.948.046.038.535.936.637.843.743.4

Elemental Composition

Ha

4.54.54.85.2

6.16.24.75.15.35.95.65.55.76.35.04.95.94.35.66.06.36.55.04.55.35.34.9

4.54.66.74.64.93.6

5.25.0

6.25.95.4

5.96.66.46.06.06.26.05.36.46.16.36.24.64.95.05.25.55.7

(%.)

Na

3.93.73.83.4

3.43.24.14.44.44.84.14.24.35.13.93.83.53.15.55.55.63.33.92.53.71.53.2

3.43.42.73.03.71.9

4.44.2

4.74.63.2

4.33.73.94.43.94.54.13.64.24.13.83.83.13.13.23.13.43.3

Ob

53.652.346.955.6

47.450.246.440.438.432.738.638.041.928.446.643.344.253.446.743.942.446.849.850.450.854.947.1

52.448.946.451.948.052.2

44.648.0

33.535.150.8

40.547.647.842.046.040.340.347.842.543.941.944.053.856.255.353.947.447.6

Ash

19.117.613.615.7

14.914.6

9.17.58.48.7

10.37.7

12.62.98.0

10.012.115.716.411.3

9.78.9

10.715.818.123.516.6

23.113.311.316.212.013.4

8.312.2

2.33.38.8

8.29.1

10.911.514.7

7.26.47.88.89.3

11.44.6

19.122.816.425.0

8.16.6

H/C

1.431.381.291.721.681.831.271.211.231.241.291.271.421.251.351.221.541.301.581.601.641.801.451.281.591.651.321.341.291.821.381.361.031.371.42

1.331.301.59

1.431.881.821.511.631.521.461.481.641.601.571.621.441.621.651.641.531.59

Atomic RatioN/C

0.0870.0810.0720.0820.0680.0680.0780.0740.0730.0730.0680.0690.0770.0730.0740.0680.0640.0680.1110.1050.1040.0650.0800.0500.0780.0340.0600.0720.0670.0520.0640.0730.0380.0830.0940.0720.0730.0790.0740.0760.0800.0790.0750.0790.0700.0710.0760.0760.0680.0710.0700.0740.0740.0710.0670.066

O/C

1.060.990.791.150.830.930.780.600.560.430.560.540.650.350.780.680.611.020.830.740.690.811.030.890.951.070.790.990.850.790.960.830.930.730.840.450.480.940.620.850.860.660.780.620.610.830.680.720.650.721.051.171.131.070.810.82

Dry-ash-free.'By difference.

1309

S. SATO

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Figure 3. Variations with depth of the E-value and H405-value in visible spectra of humic acids at Sites 438, 439, and440.

o/cFigure 4. Relationship between H/C and O/C atomic

ratios of humic acids at Sites 438, 439, and 440 on thebasis of the diagram of van Kleveln (1961).

this study show that it is necessary to separate out humicacids in addition to measuring each kerogen type in theESR study.

ACKNOWLEDGMENTS

I wish to thank Dr. Yasufumi Ishiwada for his continuingguidance during this study. Thanks are due to Mr. Tadashi As-akawa and Dr. Hiroshi Morishima for their critical reading ofthe manuscript. I am also grateful to Mr. Hideki Matsubayashiand Miss Michiko Fujiwara for their help with the ESR workand chemical analyses. I thank Dr. Jean K. Whelan for hersuggestions.

REFERENCES

Abelson, P. H., 1967. Conversion of biochemicals to kerogenand w-paraffins. [n Abelson, P. H. (Ed.), Researches inGeochemistry (Vol. 2): New York (John Wiley), 63-86.

Aizenshtat, Z., Baedecker, M. J., and Kaplan, I. R., 1973.Distribution and diagenesis of organic compounds inJOIDES sediment from the Gulf of Mexico and the westernAtlantic. Geochim. Cosmochim. Ada, 37, 1881-1893.

Forsman, J. P., 1963. Geochemistry of kerogen. In Breger, I.A. (Ed.), Organic Geochemistry: New York (Macmillan),pp. 148-182.

Forsman, J. P., and Hunt, J. M., 1958. Insoluble organicmatter (kerogen) in sedimentary rocks of marine origin. InWeeks, L. G. (Ed.), Habitat of Oil: Tulsa (AmericanAssociation of Petroleum Geologists), pp. 747-778.

1310

DIAGENETIC ALTERATION OF ORGANIC MATTER

TABLE 3ESR Data of Kerogen and Humic Acids at Sites 438,439, and 440

Sample

438-1-2438-5-3438-9-3438-11-3

438A-7-4438A-10-2438A-13-2438A-16-3438A-20-3438A-24-3328A-27-3438A-31-3438A-34-2438A-37-3438A-42-3438A-44-3438A-48-3438A-52-3438A-56-3438A-60-2438A-65-5438A-68-5438A-71-3438A-73-3438A-78-2438A-82-2438A-84-3

439-7-3439-11-3439-14-2439-18-3439-21-3439-22-3439-24-3439-26-3439-30-3439-38-1439-39-1

440-1-2440-5-5

440A-2-3440A-5-4440A-7-3

440B-4-3440B-7-3440B-I 1-3440B-14-5440B-I8-2440B-2I-3440B-24-3440B-31-3440B-35-3440B-39-3440B-4 3-3440B-4 7-1440B-51-1440B-54-3440B-58-2440B-61-I440B-66-3440B-71-1

Sub-bottomDepth

(m)

3377694

12214717520524 32X1309.US3 7540545 24735 211549587(,24676704729749795833853

872910934967996

101141024104410811 1491 154

242

87116134

1722002392703033333624284665045425786166476837111

761806

Linewidth(G)

4.884.935.085.77

5.065.014.674.924.924.724.824.824.624.274.574.074.474.572.972.872.784.273.133.283.522.884 . 7 7

4.474 223.884.814.323.734.783.934.434.624.52

3.734.92

4.117

3.232.93

4.434.284.1 74.373.484.514.324.674.875.025 (124.924.374.914.964.674 . 4 7

4 . 4 7

Kerogen

e-value

2.003032.003002.003122.00309

2.002932.1107,110

2.0030)2.003042.0029s2.0030]2.0030]2.003042.003072.0030]2.0030|2.002892.0029-)2.0030)2.002x42.002842.002802.002982.OO2832.002892.OO2832.0028o2.0029g

2.002952.002922.002892.003072.002952.OO2832.0030n2.0029T

2.002802.0027,2.0027,

2.002862.003 lo

2.002922.002802.OO283

2.002942.002862.OO2892.002982.002862.002952.002892.002922.003102.0031 32.003042.0030,2.002892.0030]2.OO3O42.002972.002922.00295

Ns(spins/gC)

X 10'8

0.600.920.820.63

0.630.560.660.390.241.452.390.471.832.791.371.562.390.870.260.280.730.970.270.470.160.610.87

0.620.640.910.530.540.401.001.470.611.882.55

0.1811.22

0.410.660.38

0.361.020.330.491.220.330.6511.270.810.470.610.620.390.650.470.6411.790.52

Linewidth(G)

7.047.656.566.06

6.556.355.666.055.816.567.156.266.076.965.885.336.576.4 75.81.5.SI5.526.573.143.383.433.136.17

6.235.727.015.575..38

5.26

6.066.55

5.826.022.93

7.657.366.867.168.557.568.398.548.677.558.839.368.766.778.469.357.866.05

Humic Acids

rvalue

2.0033]2.003332.003282.00337

2.003462.0036]2.003632.003542.003462.0035]2.0034ft2.003452.003392.0035 |2.003592.003482.003332.003362.003272.003452.0O33O2.0031 32.002792.002772.002892.OO2892.00357

2.003432.003542.003332.003422.0034g

2.00346

-

2.003492.0034]

2.003392.003362.00283

2.003352.003232.0031 32.0033]2.003132.003092.003192.003332.003422.0035 s2.003392.003332.003292.003152.003252.0031 |2.003272.00335

Ns(spins/gC)

× IO'8

0.190.280.560.44

0.760.750.340.360.470.400.550.640.710 841.170.790.751.560.41(1.270.490.290.660.340.950.640.53

0.520.590.451.072.17

-0.78

-

-

n.440.46

1.120.450.74

0.820.200.360.380.210.390.270.320.390.500.780.290.340.250.520.2411.180.65

Heistand, R. N., and Humphries, H. B., 1976. Direct deter-mination of organic carbon in oil shale. Anal. Chem., 48,1192-1194.

Ishiwatari, R., Ishiwatari, M., Kaplan, I. R., and Rohrback,B. G., 1976. Thermal alteration of young kerogen in rela-tion to petroleum genesis. Nature, 264, 347-349.

Kudo, S., Asakawa, T., and Yagishita, H., 1965. Geochemicalstudy of organic matter in petroleum source beds in the Ni-igata sedimentary basin [paper presented at the ECAFEThird Petroleum Symposium, Tokyo, Japan].

Mclver, R. D., 1967. Composition of kerogen—a clue to itsrole in the origin of petroleum. 7th World Petroleum Con-gress Proceeding, 2, 25-36.

Morishima, H., and Matsubayashi, H., 1978. ESR diagram: Amethod to distinguish vitrinite macerals. Geochim. Cos-mochim. Acta, 42, 537-540.

Nissembaum, A., and Kaplan, I. R., 1972. Chemical and iso-topic evidence for the in situ origin of marine humic sub-stances. Limnol. Oceanog., 17, 570-582.

Rashid, M. A., and Vilks, G., 1975. Geochemical environmentof methane-producing subarctic sedimentary basins of

' 8° ,° ooo o

' O o

3N30O±SI3Hd

1 r 1 r

(ID) qidθQ ujojioq-qr>s

T••••-

D c

o °.

S. SATO

10Sites 438, 439

o

CO °o

co°° o°° o o < ? Q o θ (

•t

o o

10

2.0025

Site 440

2.0030 2.0035 2.0040

o oo oo o - o o

o° „ o o

oGO

o

Kerogen

Humic Acid O

2.0025 2.0040ff-Value

Figure 6. Relationship between linewidth and g-valueon ESR spectra of kerogen and humic acids at Sites438, 439, and 440.

eastern Canada. In Campos, R., and Goni, J. (Eds.), Ad-vances in Organic Geochemistry: Madrid (Enadimsa), pp.341-356.

Sato, S., 1976. Organo-geochemical study on kerogen of sed-imentary rocks in Japan. Science Reports of the TohokuUniversity, Sendai, Japan, Third Series (Geoi), 12, 85-113.

Sato, S., Sasaki, K., and Taguchi, K., 1972. Distribution oforganic carbon and extractable organic matter in NeogeneTertiary rocks of Akita and Niigata districts, with particu-lar reference to the removal of carbonate carbons in sedi-ments. J. Geol. Soc. Jpn., 78, 643-651. (In Japanese withEnglish abstract)

Schnitzer, M., and Skiner, S. I. M., 1969. Free radicals in soilhumic compounds. Soil Sci., 108, 383-390.

Steelink, C , 1964. Free radical studies of lignin, lignin degra-dation products and soil humic acids. Geochim. Cosmo-chim. Ada, 28, 1615-1622.

Stuermer, D. H., Peters, K. E., and Kaplan, I. R., 1978. Sourceindicators of humic substances and proto-kerogen. Stableisotope ratios, elemental compositions and electron spinresonance spectra. Geochim. Cosmochim. Ada, 42, 939-997.

Taguchi, K., and Sasaki, K., 1973. Organogeochemistry andits relation to the geology of petroleum accumulation in Ja-pan. Proceedings of Symposium on Hydrogeochemistryand Biogeochemistry (Vol. 2): Washington (Clarke Com-pany), 133-157.

Tissot, B., Durand, B., Espitalié, J., and Combaz, A., 1974.Influence of nature and diagenesis of organic matter in for-mation of petroleum. Bull. Am. Assoc. Petrol. Geol., 58,499-506.

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van Kleveln, D. W. (Ed.), 1961. Coal: Amsterdam (Elsevier).

Watanabe, H., 1972. Humic substances in the bottom sedi-ments of Lake Abashiri, Hokkaido, Japan. J. Geol. Soc.Jpn., 78, 393-403. (In Japanese with English abstract)

Welte, D., 1973. Recent advances in organic geochemistry ofhumic substances and kerogen. In Tissot, B., and Bienner,F. (Eds.), Advances in Organic Geochemistry: Paris (Edi-tions Technip), pp. 3-13. (Review)

Yagishita, H., 1962. Distribution of hydrocarbons in Neogenesedimentary rocks of Niigata as a clue to recognition of pe-troleum source rock. / . Jpn. Assoc. Petrol. Tech., 27,265-296. (In Japanese with English abstract)

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