35. CHARACTERIZATION OF INSOLUBLE ORGANIC MATTER IN SEDIMENTS FROM THENANKAI TROUGH, DEEP SEA DRILLING PROJECT LEG 87A1

Tsutomu Machihara, Technology Research Center, Japan National Oil Corporation2

ABSTRACT

Lipids, humic acids, and kerogens were isolated from Site 582 sediment cores. The amount of each organic fractionin the samples taken from 5.6 to 694 m sub-bottom is almost unrelated to depth of the sample. A study of the oxidationof organic matter by the alkaline KMnO4 method reveals that distribution of polymethylene chain lengths of the kero-gens and humic acids in the marine sediments differ from those in lacustrine sediments. The order of abundance ofthese chains in the sediments is: kerogens, 52-66% of total methylene chains; humic acids, 25-33%; and lipids, 8-16%.The results suggest that polyunsaturated fatty acids ( > 4 double bonds) may be important in the formation of poly-methylene chains of kerogens and humic acids in marine sediments.

INTRODUCTION

Insoluble organic matter (kerogen) constitutes a ma-jor portion of all organic matter in sediments. Manydegradation studies, such as oxidation studies (Philp andYang, 1977; Machihara and Ishiwatari, 1981) and pyrol-ysis studies (Philp et al., 1978; Sklarew, 1979), have shownthe presence of polymethylene chains ( - (CH2)n - ) inthe kerogen structure. However, precursors and the for-mation process of polymethylene chains in kerogen arenot well known. The study of the chemical structure andthe source of the polymethylene chains in kerogens isimportant, because thermal degradation may transformthese chains into aliphatic petroleum hydrocarbons(Welte, 1972; Tissot and Welte, 1978; Hunt, 1979).

In a previous report (Ishiwatari and Machihara, 1983),we examined lipids, humic acid, and kerogen in lacus-trine sediment by the KMnO4 oxidation method. Thoseresults demonstrate that the molecular distribution ofpolymethylene chains (normal aliphatic α,w-dicarboxyl-ic acids as major degradation products) are similar amongthe three fractions. This similarity indicates a commonorigin for the polymethylene chains of these three or-ganic materials.

We report on the study of oxidation of three organicfractions (lipids, humic acid, and kerogen) from Site 582samples, in order to compare the characteristics of thesethree organic materials from a marine sediment in termsof their polymethylene chains. Humic acid was includedin this study, because some marine sediments containthese acids in relatively large amounts (Degens et al.,1964; Stuermer et al., 1978; Sato, 1980).

METHODS

Sample Description

Sediment samples used in this study are muds (Cores 582-1 and582B-3 to 582B-5O) or mudstones (Cores 582B-58 and 582B-68) of

Kagami, H., Karig, D. E., Coulbourn, W. T., et al., Init. Repts. DSDP, 87: Washing-ton (US. Govt. Printing Office).

* Address: Technology Research Center, Japan National Oil Corporation, 3-5-5, Midori-gaoka, Hamura-cho, Nishitama-gun, Tokyo, 190-11 Japan.

Quaternary age (Table 1). Age at the base of Hole 582B (749.4 m) isapproximately 0.65 Ma (Kagami et al., 1983).

Separation of Lipids, Humic Acid, and Kerogen

A freeze-dried sediment sample (50-67 g) was ground to a finepowder and extracted with benzene-methanol (6:4) in a Soxhlet appa-ratus for 70 hr. to remove lipids. Sulfur was removed by adding copperto the boiling solution. A portion (approximately 30 g) of the sedi-ment residue was subsequently extracted with a solution of 0.5 NNaOH (50 ml × 5) by ultrasonication (20 kHz; 60 minutes × 3) at ap-proximately 50°C to remove humic and fulvic acids. The alkaline solu-tion was filtered through a Whatman GF/C filter, acidified with 6 NHC1 to a pH of approximately 1 and centrifuged to obtain the humicacid. This acid was purified by dissolution in a 0.2 N solution ofNaOH, filtered through a GF/C filter, acidified to a pH of approxi-mately 1, and centrifuged. The resulting humic acid was rinsed withdistilled water and freeze-dried. The residue from the alkaline extrac-tion was treated with 46% HF/6 N HC1 (1:1) solution to decomposeinorganic materials. The kerogen was concentrated from the inorgan-ics by using heavy liquid (ZnCl2 at specific gravity 2.0). The kerogenthus obtained was washed with distilled water and freeze-dried. Be-cause the ash content of the kerogen was high (60-70%), it was furthertreated with 6 N HC1 at 95 °C for 10 hr. in order to decrease inorganicmaterials.

Alkaline Potassium Permanganate Oxidation

The methods of oxidation and extraction of degradation productsare reported in detail elsewhere (see Machihara and Ishiwatari, 1983).Briefly, a sample (2-20 mg) of lipids, humic acid, or kerogen wasmixed with 10 ml of 2% KMnO4 in 1 % KOH aqueous solution and al-lowed to react for 60 minutes at 60° C. The degradation products wereextracted, silylated, and analyzed by gas chromatography (GC) or gaschromatography-mass spectrometry (GC-MS).

Instrumentation

GC analyses were carried out on a Hewlett-Packard 5840A gaschromatograph with a flame ionization detector. GC separations wereperformed using a Hewlett-Packard OV-1 fused silica capillary column(25 m long × 0.31 mm internal diameter). The column temperaturewas programmed from 90-280°C at 10°C/minute.

Degradation products were quantified by measuring their peakheights or peak areas on the gas chromatograms. Standards are nor-mal saturated monocarboxylic acids (C9, C10> C12, C14, Ci6, C l g , C20,and C22); normal saturated α,w-dicarboxylic acids (C4, C 6 , C 8 , andC 1 0 ); 2,2-dimethyl succinic acid; and benzenecarboxylic acids (ben-zoic, phthalic, and trimesic acids).

The degradation products were confirmed with a Hewlett-Packard5985 gas chromatograph-mass spectrometer. The temperature and col-umn conditions were the same as used for GC analyses. Helium wasused as carrier gas. The mass spectrometer was operated at an electron

891

T. MACHIHARA

energy of 70 eV, a separator temperature of 300°C, and an ion sourcetemperature of 200° C.

CHN Analyses

Organic carbon in sediment samples and elemental analyses of lip-ids, humic acid, and kerogen were determined with a Yanagimoto CHNanalyzer (Type MT-2).

Isotopic Measurements

δ 1 3C values were obtained using a Varian Mat 250 isotope massspectrometer. PDB was used as the standard.

RESULTS AND DISCUSSION

The lipid contents of Cores 582-1 and 582B-3 arehigher than those of deeper samples, whereas the humicacid and kerogen contents of the same cores are slightlylow compared to those of deeper sediments (Table 1;Fig. 1). In the cores deeper than 130 m sub-bottom, theamounts of lipids, humic acid, and kerogen are practi-cally constant: 2.8 to 4.1% for lipids, 12 to 14% for hu-mic acids, and 42 to 50% for kerogens. Some of the to-tal organic matter (36-49%) was not recovered; it prob-ably consists of fulvic acids and low molecular weightcompounds.

The H/C and O/C ratios for kerogens are lower thanthose for the humic acids (Table 2; Fig. 2). This distinc-tion may arise from the different methods of separationof humic acid and of kerogen from the sediment sam-ple; that is, humic acid is not treated with mineral acids,whereas kerogen is treated with 6 N HC1 for 10 hr. to di-minish inorganic materials. For example, upon hydroly-sis of kerogen from Lake Haruna sediment with 6 NHC1 (Machihara and Ishiwatari, 1980), the ratios of H/C and O/C decreased substantially: 1.17 to 0.81 and0.44 to 0.38, respectively. Although a similar change mayhave occurred for the kerogens in this experiment, wehave no data to ascertain this point, because the ashcontent of the kerogen is too high (60-70 wt.%) to ob-tain accurate evaluations of the hydrogen and oxygencontents.

δ13C values of the three fractions change almost inparallel with depth except for a slight low value of theCore 582-1 lipids (Fig. 3), indicating a common sourcefor each. The δ13C for each organic fraction of the sam-ple from Core 582B-68 is relatively high, suggesting thatthis sample has more organic matter from a marine source

Table 1. Organic carbon, lipids, humic acids, and kero-gens in sediments at Site 582.

Amounts (% as carbon in total carbon)10. 20 30 40 50 60

Hole-Core-Section

582-1-4582B-3-1582B-10-2582B-16-1582B-22-1582B-30-6582B-40-1582B-50-2582B-58-2582B-68-2

Sub-bottomdepth

(m)

675

137194252336423520598694

Organiccarbon

(%)

0.540.660.430.690.650.550.520.460.260.35

LipidsHumic

acid Kerogen

(mg C/g dry sediment)

0.330.460.150.270.180.240.150.190.0760.14

0.380.680.581.000.85

0.810.66

0.44

2.072.242.132.952.942.792.372.031.091.45

Δ

_ Δ

Δ

Δ

Δ

Δ

- Δ

_ Δ

Δ

1

o

1

o

o

o

o

o

o

1

1

1 1

•

•

i

•

•

•

I 1

1

•

-

•

•

-

-

-

1

Note: Blanks indicate no measurement made.

100 -

200 -

_ 300E

ε 400 -

500 -

600

700

800

Figure 1. The relation of amounts of lipids (triangles), humic acids(open circles), and kerogens (solid circles) in Site 582 sediments tosub-bottom depth.

than do the other four sediment samples (Degens, 1969).This pattern conforms with sedimentologic, biostrati-graphic, and physical properties observations that iden-tify Core 582B-54 as the border between Nankai Troughturbidites above and Shikoku Basin sediments below (sitechapter, Site 582, this volume).

Oxidative degradation products obtained from the threefractions are normal α,co-dicarboxylic acids, benzene-carboxylic acids, normal monocarboxylic acids, and2,2-dimethyl succinic acid (Table 3). These products arecommonly observed in oxidation studies of organicmatter (lipids, humic acid, and kerogen) in lacustrinesediments (Machihara and Ishiwatari, 1981; Machihara,1981). For Leg 87 samples, normal α,co-dicarboxylicacids of the lipids have peaks at C4, C6, and C9 (Core582-1, Fig. 4A) or C6 and C9 (Cores 582B-10, 582B-22,and 582B-50), whereas those of the humic acids and ke-rogen show a maximum peak at C4 (Figs. 4B; 4C). Thedistribution pattern of the benzenecarboxylic acids arealmost the same among the three fractions.

A large portion of the α,ü>-dicarboxylic acids of thelipids may have been derived from unsaturated fatty acidsor their alteration materials (Ishiwatari and Machihara,1983). We have observed that lipids extracted from algae(bluegreen and green algae and diatoms) generate C4-C12 α,co-dicarboxylic acids (with a maximum peak at C8

or C9) by their KMnO4 oxidation (Ishiwatari and Machi-hara, 1982). We have also obtained large quantities ofC4-C9 α,α>-dicarboxylic acids with a maximum peak at

892

INSOLUBLE ORGANIC MATTER IN NANKAI TROUGH SEDIMENTS

Table 2. Elementary composition and *•*C values of lipids, humic acids, and kerogens.

Fraction

Lipids

Humic acids

Kerogens

Hole-Core-Section

582-1-4582B-3-1582B-10-2582B-16-1582B-22-1582B-30-6582B-40-1582B-50-2582B-58-2582B-68-2582-1-4582B-3-1582B-10-2582B-16-1582B-22-1582B-30-6582B-40-1582B-50-2582B-58-2582B-68-2582-1-4582B-3-1582B-10-2582B-16-1582B-22-1582B-30-6582B-40-1582B-50-2582B-58-2582B-68-2

Elemental analysesa (%)

C

75.680.582.082.377.981.178.879.879.880.456.255.255.755.456.355.457.158.561.960.871.269.670.568.969.969.271.671.670.465.4

H

9.6611.3 (11.211.3 (10.811.411.011.011.010.84.904.895.53 .5.526.005.275.06 I4.94 :5.035.69 '3.91 :4.174.204.634.334.364.62 .4.574.024.i9 :

N

.51).97,50

).9O.49.05.47.22.54.58

S.50S.91S.44J.325.39$.77>.99>.795.491.22>.141.95.74.86.80

1.92>.08.91.88

U 6

O b

13.287.185.285.519.826.518.717.997.727.20

35.436.035.335.634.335.634.933.829.629.322.824.323.524.624.024.621.721.923.628.2

Ash(<%)

4.6011.044.844.639.8

4.9024.127.6

1.42.86.477.979.007.438.126.935.606.50

15.120.5

Atomic ratios

H/C

1.541.691.641.651.671.681.681.651.651.621.051.061.191.201.281.141.061.010.971.120.660.720.710.810.740.760.770.760.680.77

N/C

0.0170.0100.0160.0090.0160.0110.0160.0130.0170.0170.0530.0610.0530.0510.0520.0580.0450.0410.0480.0590.0260.0240.0210.0230.0220.0240.0250.0230.0230.028

O/C

0.130.070.050.050.090.060.080.080.070.070.470.490.480.480.460.480.460.430.360.360.240.260.250.270.260.270.230.230.250.32

δ 1 3 C(‰ vs. PDB)

-25.8

-25.7

-25.7

-25.8

-25.2-22.2

-23.4

-23.3

-23.1

-20.7-23.4

-24.3

-24.6

-24.3

-22.9

Note: Blank indicates not measured.a Ash-free basis.b By difference.

1 .«*

b

ro

Myα

rog

en/

o co

0.6

0.4

1 1 1

-

y *_

i i i

0

o

1 1

o

8o

Cb O

o

-

-

_

1 10.0 0.1 0.2 0.3 0.4

Oxygen/Carbon0.5 0.6

Figure 2. The oxygen/carbon versus hydrogen/carbon atomic ratiosfor the humic acids and kerogens. Symbols as in Figure 1.

C 8 or C 9 by oxidation of authentic standards such as Δ9-C 1 6 : 1 , Δ9-C1 8 : 1, Δ 9 ' 1 2-C 1 8 : 2, and Δ9>12>15-C18:3 (Machiharaand Ishiwatari, 1983).

Interestingly, the distribution pattern of α,oo-dicarbox-ylic acids obtained from the kerogens (and humic acids)in these marine sediments is different from those in

- 2 8

582-1-4 -

c 582B-10-2 -

582B-22-1 -

δ 1 3 C (°/oo versus PDB standard)-26 - 2 4 - 2 2 - 2 0 - 1 8

I

Δ

- Δ

Δ

_ Δ

-

I

Δ

I

•

•

•

I

•

o

o

o

•

I

o

I

I

o

I

I

-

-

-

-

-

I

582B-50-2 -

582B-68-2 -

Figure 3. δ 1 3C values in each organic fraction for samples from Holes

582 and 582B. Symbols as in Figure 1.

lacustrine sediments (Machihara and Ishiwatari, 1980,1981). In other words, α,to-dicarboxylic acids of the ma-rine sediments have a maximum peak at C4 and decreasewith increasing carbon numbers, whereas those of thelacustrine sediments show a maximum peak at C8. Thiscontrast may be due to the difference of precursor mate-

893

T. MACHIHARA

Table 3. Yield of organic compounds produced by oxidation of eachfraction (expressed as mg/g organic carbon).

Hole-Core-Section

582-1-4

582B-1O-2

582B-22-1

582B-50-2

Degradation products

n-Cg ~ n-C26 monocarboxylic acidsn-C4~n-Cj4 α.α>-dicarboxylic acidsBenzenecarboxylic acids2,2-dimethyl succinic acid

Totaln-Cg ~ n-C26 monocarboxylic acidsn-C4~n-Ci4 α.α>-dicarboxylic acidsBenzenecarboxylic acids2,2-dimethyl succinic acid

Totaln-Cg ~ n-C26 nionocarboxylic acidsn-C4~n-Cj4 α,ü)-dicarboxylic acidsBenzenecarboxylic acids2,2-dimethyl succinic acid

Totaln-Cg ~ n-C26 monocarboxylic acidsn-C4~n-Ci4 α.α>-dicarboxylic acidsBenzenecarboxylic acids2,2-dimethyl succinic acid

Total

Lipids

5.3916.516.5

1.8340.2

7.4622.4

7.01.36

38.29.82

40.47.62.40

60.28.96

31.76.22.04

48.9

Humicacid

3.9534.4

6.21.63

46.21.58

24.15.941.38

33.01.29

24.33.411.40

30.42.06

22.45.951.62

32.0

Kerogen

0.5910.55.470.54

17.12.02

15.86.030.87

24.71.89

16.95.620.9425.41.70

14.210.00.84

26.7

rials (i.e., unsaturated fatty acids). The composition ofunsaturated fatty acids is remarkably different betweenfresh-water and seawater algae (Pohl et al., 1968; Jamie-son and Reid, 1972). The former consist mainly of Δ7-or Δ9-C1 6 : 1, Δ

9-C18:i, Δ9 1 2 -C 1 8 : 2 , and Δ9.12-15-C18:3, where-

as the latter, in addition to those unsaturated fatty acids,contain polyunsaturated fatty acids ( > 4 double bonds)such as Δ6•9 12 1 5 -C 1 8 . 4 , Δ 5 ' 8 ' 1 1 - 1 4 -*:^, Δ 8 . 1 1 - 1 4 . 1 7 - ^ ,Δ5,8,n,i4,i7_c20:5)

7.10.1'3'16'19-^^, and Δ 4 . 7 ' 1 0 . 1 3 . 1 6 ' 1 9 -^ .Therefore, if we assume that polyunsaturated fatty acids( > 4 double bonds) have been incorporated in the kero-gen and humic acids, then C4-C7 α,α>-dicarboxylic acidsshould be produced from the oxidation of kerogen andhumic acids; e.g., C4, C5, C6, and C7 from 4 7 10•13'16'19-C « Λ5,8,11,14.P Λ6,9,12,15 f t an(\ A7,10,13,16,19 f-

M2:6i ^ W0:4> ^ Mδ:4» a n α ** ~̂ 22:5>respectively.

The distribution patterns of α,w-dicarboxylic acidsbetween lipids and kerogen (or humic acid) differ fromeach other. In the case of the oxidation study of threeorganic fractions (lipids, humic acid, and kerogen) in alacustrine sediment, such differences were not observed(Ishiwatari and Machihara, 1983). This contrast may beinterpreted in terms of the reactivity of unsaturated fat-ty acids with kerogen (or humic acid). Polyunsaturatedfatty acids (>4 double bonds) may have reacted moreeasily with kerogen (humic acid) than unsaturated fattyacids (< 3 double bonds) and were incorporated in theirmatrices. On this assumption, lipids become richer inC1 6 : 1 and C18:12>3 unsaturated fatty acids (or their altera-tion products), compared to kerogen (or humic acid).Thus, upon oxidation, lipids would generate α,co-dicar-boxylic acids with a maximum at C8 or C9. At present,however, this interpretation is speculative. Further studyis needed to elucidate the high reactivity of polyunsatu-rated fatty acids (>4 double bonds) with kerogen andtheir incorporation into kerogen matrix.

In all of the oxidation products of the three fractions,2,2-dimethyl succinic acid was detected. A precursor ofthis acid is probably carotenoid pigments (e.g., /3-caro-

tene; Machihara and Ishiwatari, 1983). Although smallamounts of 2,2-dimethyl glutaric acid, which is also ob-tained by oxidation of ß-carotene, were detected, its yieldwas not measured in this experiment. Yield of 2,2-di-methyl succinic and glutaric acids produced from theoxidation of 0-carotene was 5.5 wt.% (Machihara andIshiwatari, 1983). Therefore, the content of ß-carotenein the lipids, humic acid, and kerogen in the sedimentscan be estimated approximately, assuming that 2,2-di-methyl succinic acid was derived from ß-carotene (or re-lated compounds). The amount is calculated as 2.5 to4.4% for the lipids, 2.5 to 2.9% for the humic acids,and 0.9 to 1.6% for the kerogens.

The amounts of polymethylene chains in the threeorganic fractions in the sediments were calculated (Ta-ble 4) using the quantified amounts of the three frac-tions (Table 1) and the yields of aliphatic acids producedby the oxidation of each fraction (Table 3). In this calcu-lation, the yield of aliphatic acids from polymethylenechains by KMnO4 oxidation was assumed to be the samefor the three fractions. The order of abundance of thesechains in the sediments is kerogen, 52-66% of totalmethylene chains; humic acid, 25-33%; and lipids, 8-16%. The distribution of polymethylene chains amongthe three fractions is almost unrelated to depth of thesample.

CONCLUSIONS

1. The amounts of lipids, humic acids, and kerogensin sediment cores (5.6-694 m) were almost unrelated todepth of the samples. The order of amounts of thesetypes of organic matter in the sediment is kerogens, 34-51% of total organic carbon; humic acids, 7.1-15.5%;and lipids, 2.4-7.0%.

2. δ13C values of the three fractions varied almost inparallel with depth. This uniformity indicates a com-mon source for the lipids, humic acid, and kerogen ineach sediment sample.

3. Oxidation study of the each fraction showed thatthe distribution pattern of polymethylene chain lengthsdiffers between the lipids and kerogen (or humic acid).Thus, polyunsaturated fatty acids ( 4 double bonds)may play an important role in the formation of poly-methylene chain structure in marine kerogen and humicacid.

4. A significant amount of carotenoid pigments mayalso be responsible for the polymethylene chain struc-ture in kerogen and humic acid.

5. The polymethylene chains in the sediments are dom-inant in the kerogen fraction. The abundance was calcu-lated to be 52 to 66% of total methylene chains in thesediments.

ACKNOWLEDGMENTS

I would like to thank Japan National Oil Corporation (JNOC) forthe permission to publish the paper. Thanks are due to Dr. K. Aoyagiand Dr. S. Sato (JNOC) for their continuing encouragement duringthis work. I am also grateful to Mr. M. Omokawa (JNOC) for the car-bon isotope analysis, and Dr. P. Schenk of Dalhousie University forhis valuable comments on the manuscript. I wish to thank Dr. Y. Ishi-wada (JNOC) for giving me the opportunity to participate in Leg 87.

894

INSOLUBLE ORGANIC MATTER IN NANKAI TROUGH SEDIMENTS

R-COOH HOOC-R-COOH •(COOH)N

R-COOH HOOC-R-COOH O-(C00H) N

I β

o

! 4

o

=s2

2 0

4

2

0

A. Lipids

582-1-4

i i , . . 1 i 1 , i i

582B-10-2

i , . . . . I . I . , . I . i

582B-22-1

I , . , . I . I . I . I , I

582B-50-2

I i . . . i . 1 . 1 . 1 . 1 i 1

Him

II

1,

1 1

1 1 1

III,.

I I I .

ó

é

ll

1 1

11

r

t><

I

1

\/JÓL

/12 16 20 24 4 8

Carbon number12

4

'a r>

B 2

B. Humic Acid582-1-4

i . i . . i I . I . . .

582B-10-2

582B-22-1

582B-50-2

lit,

I i ,

i i

I

I I I , , , . .

II..

, 1

l l , .

i

i

i

iá

1/JÓL/

12 16 20 24 4 8Carbon number

12

R-COOH HOOC-R-COOH O-(C00H)N

.9 6

I6

o. 4

tz° 2(0

Iβ 0σ>

o 6

4

2

C. Kerogen582-1-4

582B-10-2

i i

582B-22-1

582B-50-2

I

Illl I I .

Illl,,.

Illli i I . .

|

ò\I

. l l .

. I I

. 11

I /12 16 20 24 4 8

Carbon number12

Figure 4. Distributions of aliphatic monocarboxylic and dicarboxylic acids and benzenecarboxylic acids in the oxidation products. A. Lipids;B. Humic acid; C. Kerogen. R-COOH, HOOC-R-COOH, and ^ -(COOH)N indicate aliphatic monocarboxylic acids, aliphatic α.α>-di-carboxylic acids, and benzenecarboxylic acids, respectively.

Table 4. Distribution of polymethylene chains in the sediments.

Hole-Core-Section

582-1-4582B-10-2582B-22-1582B-50-2

Concentration of polymeth-ylene chains in the sediment

Lipids

7.04.59.07.7

G*g/g C)

Humicacid

14.214.921.815.6

Kerogen

22.538.055.332.3

Relative abundance (%)

Lipids

167.8

1114

Humicacid

33262528

Kerogen

52666458

REFERENCES

Degens, E. T, 1969. Biogeochemistry of stable carbon isotopes. InEglinton, G., and Murphy, M. T. J. (Eds.), Organic Geochemistry:New York (Springer-Verlag), pp. 304-329.

Degens, E. T., Reuter, J. H., and Shaw, N. R, 1964. Biochemical com-pounds in offshore California sediments and seawater. Geochim.Cosmochim. Ada, 28:45-66.

Hunt, J. M., 1979. Petroleum Geochemistry and Geology: San Fran-cisco (W. H. Freeman and Company).

Ishiwatari, R., and Machihara, T., 1982. Algal lipids as a possiblecontributor to the polymethylene chains in kerogen. Geochem.Cosmochim. Acta, 46:1459-1464.

895

T. MACHIHARA

, 1983. Early stage incorporation of biolipids into kerogen ina lacustrine sediment: evidence from alkaline potassium perman-ganate oxidation of sedimentary lipids and humic matter. Org.Geochem., 4:179-184.

Jamieson, G. R., and Reid, E. H., 1972. The component fatty acids ofsome marine algal lipids. Phytochemistry, 11:1423-1432.

Kagami, H., Karig, D. E., and Shipboard Scientific Party, 1983. Leg87 drills off Honshu and southwest Japan. Geotimes, 28 (1):15-18.

Machihara, T., 1981. Geochemical studies of organic matter (kerogen)in recent sediments [Ph.D. thesis]. Tokyo Metropolitan University,Tokyo.

Machihara, T., and Ishiwatari, R., 1980. Characterization of youngkerogen in a lacustrine sediment by alkaline permanganate oxida-tion. Geochem. I, 14:279-288.

, 1981. Characteristics of insoluble organic matter in lakesediments as revealed by alkaline potassium permanganate oxida-tion. Verh. Int. Ver. Limnol., 21:244-247.

., 1983. Evaluation of alkaline permanganate oxidation meth-od for the characterization of young kerogen. Org. Geochem., 5:111-119.

Philp, R. P., Calvin, M., Brown, S., and Yang, E., 1978. Organic geo-chemical studies on kerogen precursors in recently deposited algalmats and oozes. Chem. GeoL, 22:207-231.

Philp, R. P., and Yang, E., 1977. Alkaline potassium permanganatedegradation of insoluble organic residues (kerogen) isolated fromrecently-deposited algal mats. Energy Sources, 3:149-161.

Pohl, P., Wagner, H., and Passig, T., 1968. Inhaltsstoffe von Algen-II.über die unterschiedliche fettsaurzusammensetzung von salz- undsüsswasseralgen. Phytochemistry, 7:1565-1572.

Sato, S., 1980. Diagenetic alteration of organic matter in Leg 57 sedi-ments, Deep Sea Drilling Project. In Scientific Party, Init. Repts.DSDP, 56, 57, Pt. 2: Washington (U.S. Govt. Printing Office),1305-1312.

Sklarew, D. S., 1979. Analysis and simulated diagenesis of kerogen ina Recent bottom mud from Mono Lake, California: a comparisonwith selected ancient kerogens. Geochim. Cosmochim. Acta, 43:1949-1958.

Stuermer, D. H., Peters, K. E., and Kaplan, I. R., 1978. Source indi-cators of humic substances and proto-kerogen. Stable isotope ra-tios, elemental compositions and electron spin resonance spectra.Geochim. Cosmochim. Acta, 42:989-997.

Tissot, B. P., and Welte, D. H., 1978. Petroleum Formation and Oc-currence: Berlin, New York (Springer-Verlag).

Welte, D. H., 1972. Petroleum exploration and organic geochemistry.J. Geochem. Explor., 1:117-136.

Date of Initial Receipt: 13 January 1984Date of Acceptance: 13 July 1984

896