Organic geochemistry of recent sediments from Guaymas Basin, Gulf of California

Deep-Sea Research,Vol. 26A,pp. 879 to 891 ~ 1979PergamonPress Ltd 1979.Printed in Great Britain

0011-7471/79/0801-0879$02.00/0

Organic geochemistry of recent sediments from Guaymas Basin, Gulf of California* BERND R. T. SIMONEITt, M. A. MAZUREKt, S. BRENNERt, P. T. CRISPt and I. R. KAPLANt~ (Received 12 December 1978; in revised ]brm 28 December 1978, accepted 1 Februarv 1979)

Ahstraet--A 3.5-m gravity core taken from the Guaymas Basin, Gulf of California, was analyzed for lipids, humates, kerogens, and C 1 to C s hydrocarbons. The analyses were of interest due to the high geothermal gradient observed in the Guaymas Basin and the strong petroliferous odor of the sediment. Analyses were by gas chromatography (GC), GC-mass spectrometry, and stable isotope mass spectrometry. The bulk of the organic matter (humates and kerogens) was of marine origin and diagenetically immature. The molecular markers of the hydrocarbons, fatty acids, and ketones were of a predominantly marine autochthonous origin. A small and variable component of allochthonous lipids from terrestrial plants was also present. Methane was principally of biogenic origin, but the lower sections of the core contained significant concentrations (7 Ilg g-1 dry sediment) of petrogenic C 2 to C a hydrocarbons. INTRODUCTION THE GULF OF CAUFORN1A is a long ( l l o o km) structural trough that contains a n u m b e r of deep semi-closed basins (VAN ANDEL and SHOR, 1964; BYRNE and EMERY, 1960). D u r i n g the H y p o g e n e Expedition by the Scripps Institution of O c e a n o g r a p h y (SIO) in 1972, several basins, including the G u a y m a s Basin (Fig. 1), were cored for sediments. The G u a y m a s Basin is of special geochemical interest, since high heat flow values (7 to 10 lacal cm - 2 s - ~) were measured there. It is also a proposed drill site of the Deep-Sea Drilling P r o j e c t - I P O D . The basin is a gently sloping trough containing, on the average, 1 0 0 m of hemipelagic sediment c o m p o s e d of biogenic carbonate, opaline silica (diatom frustules), and clays. A b o u t 50~o of the sediment is opal and this can be related to upwelling of nutrients and subsequent high productivity of diatoms (BYRNE and EMERY, 1960). The b o t t o m waters appear to be oxic (BYRNE and EMERY, 1960). A gravity core from the northern G u a y m a s Basin (site 3 0 G ; 27°23.0'N, 111°26.9'W; 1076-m water depth; GOLDHABER, 1974; KALIL, 1976) collected in 1972 by the S I O H y p o g e n e Expedition had a strong petroliferous odor. In view of the high heat flow of the basin, the organic matter of this core was examined in detail to assess potential petrogenesis within the Q u a t e r n a r y sediment. EXPERIMENTAL PROCEDURE The core, taken in March 1972, on the R.V. M e l v i l l e was immediately cut into approximately 1-m lengths, capped, and stored at - 2 0 ° C in the original core liner. * Contribution No. 1814: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90024, U.S.A. t Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90024, U.S.A. ++Department of Earth and Space Science, University of California, Los Angeles, CA 90024, U.S.A. 879

880

SIMONEIT,M. A. MAZUREK, S. BRENNER,P. T. CRISP and I. R. KAPLAN

BERND R. T.

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Lipids Samples were treated with 6 M hydrochloric acid, washed with distilled water and then freeze-dried. The sediments were extracted with chloroform : methanol (1 : 1) on a shaker table with 3 to 6 solvent changes. An aliquot of the extract was treated with boron

Organic geochemistryof recent sediments from Guaymas Basin, Gulf of California

881

Table 1. Designations,carbon analyses and ages of the Guaymas Basin sediment samples Carbon* Sample No.

Sample designation

Subbottom depth (m)

Total (~)

1 2 3 4 5 6 7

30- G-I 30-G-II 3~G III 30- G-IVa 30-G-IVb 30--G-Va 3(~G Vb

1.02 1.05 1.73 1.79 2.25 2.29 2.51 2.58 2.94~2.99 3.38 3.45 3.45 3.49

2.80 2.80 3.30 2.75 2.83 2.22 2.37

Organic(~) CaCOat (~o) 2.47 1.77 2.51 2.54 1.93 2.07 1.73

3 9 4 2 7 1 5

Inferred age* (yr b.p.) 500 900 1100 1300 1500 1700 1800

* Determined using a LECO analyzer, t Calculated from carbon analyses. ++Based on sedimentation rate of ~2 m/1000 yr. trifluoride in methanol to esterify free fatty acids and was subjected to thin-layer chromatography (TLC) on silica gel using methylene chloride as eluent. The bands corresponding to hydrocarbons, esters, and ketones were scraped off the T L C plate and eluted with methylene chloride. The ester and ketone fractions were combined. The two resulting fractions were analyzed by gas chromatography (GC) and gas c h r o m a t o g r a p h y mass spectrometry ( G C - M S ) . Some hydrocarbon fractions were further separated by TLC, using silica gel plates and pentane as eluent. The plates showed very low u.v. fluorescence and the retention regions corresponding to saturated and olefinic hydrocarbons, alkylarenes, and polynuclear aromatic hydrocarbons were scraped off the plates, eluted with methylene chloride, and subjected to G C and some G C - M S analyses. The G C analyses were carried out on a Varian-Aerograph Model 1520C gas chromatograph. A 15-m x 0.25-mm glass capillary column wall-coated with OV-101 was used and programmed from 40 to 260°C at 6°C m i n - 1, then held isothermal for 50 min. The flow rate of the helium carrier gas was 2 ml m i n - 1 (30 cm s - 1 linear velocity). The G C - M S analyses were carried out on a Finnigan Model 4000 quadrupole mass spectrometer interfaced directly with a Finnigan Model 9610 gas chromatograph equipped with a glass capillary column (30-m x 0.25-mm, wall-coated with OV-101 ; J & W, Inc.). The G C conditions for the G C MS analyses were the same as those for the analytical G C system. The mass spectrometric data were acquired and processed using a Finnigan I N C O S Model 2300 D a t a System.

Humates and kerogens Humates and kerogens were isolated by the methods described by STUERMER,PETERSand KAPLAN (1978). Carbon, hydrogen, nitrogen, and ash were determined by the Microanalytical Laboratory, Department of Chemistry, University of California, Berkeley. Stable carbon isotope analyses were carried out by the method of KAPLAN,SMITH and RUTH (1970). The results are given in the '6' notation versus the Chicago PDB standard, where :

t~13C(°/°°)=IRsamp'e--Rstandard--ll L Rstandard X 1000, and R is the

13C/12Cratio.

882

BERND R. T. SIMONEIT, M. A. MAZUREK,S. BRENNER, P. T. CRISP and I. R. KAPLAN

C1 to C 8 hydrocarbons

Freshly-cut core sections were partially thawed to facilitate removal from the core liner, peeled, and transferred to 600-ml steel cans. The cans were filled with water until 100 ml of air remained, sealed, and frozen at - 20°C (to prevent bacterial activity) until immediately prior to analysis. The cans were thawed (20°C), shaken vigorously for 3 rain, punctured, and samples of the gas phase were injected into a Hewlett-Packard 5830A gas chromatograph. A Durapak column (T. M. Waters Associates; 3 m x 3.5 mm) and a flame ionization detector were used. The temperature program was: - 5 0 ° C (2 min), - 5 0 to 10°C (10°Cmin-~), 10 to 100°C (4°Cmin -~) and 100°C (15min). The sediments remaining in the cans after gas analysis were freeze-dried and weighed. Hydrocarbon concentrations are reported as lag g-1 of dry sediment. The accuracy of the analytical procedure was assessed by injecting C~ to C6 alkanes, ethylene, and propylene into canned sediments under identical conditions to yield gas concentrations of 5 ng ml - ~ in the headspace. After vigorous shaking for 2 rain at least 85~o of each hydrocarbon remained in the gaseous phase and the quantity did not change with further shaking. Higher percentage recoveries were obtained with higher gas concentrations. Similar studies have been reported in the literature. MclvER (1973) found a negligible amount of methane remaining in the aqueous sediment phase during analysis of canned samples by a headspace method. MCAULIFFE(1969) demonstrated that C1 to Ca n-alkanes partition >95~o in the gaseous phase when equilibrated with equal volumes of air and water and that the percentage increases with increasing carbon chain length. Methane was combusted at 800°C on copper oxide and the resulting carbon dioxide analyzed for stable carbon isotopes following the method of KAPLANet al. (1970).

RESULTS AND DISCUSSION

Sample descriptions and results of the elemental analyses are given in Table 1. The organic carbon values are typical of hemipelagic sediments. The geologic age range of these samples is 500 to 1800 years b.p., based on an average sedimentation rate of 2 m per 1000 years (KALIL, 1976). Lipids

The lipid yields were relatively high (5 to 200 ppm ; Table 2). The distribution patterns of the n-alkanes, n-fatty acids, and n-alkylmethylketones are shown in Fig. 2. The n-alkanes of samples 1 and 7 [Fig. 2(a)-(e)] reflect a predominantly marine autochthonous origin, where the maximum at n-C~7 and n-C19 represents a primary residue of bacteria and algae (HAN, MCCARTHY, CALVINand BENN, 1968; YOUNGBLOOD, BLUMER, GUmLARDand FIORE, 1971; OR6, TORNABENE,NOONER and GELPI, 1967). The homologs > n-C24 and maximizing at n-C29 represent a minor component from higher plant wax (SIMONEIT, 1975; 1978a, b). The n-alkanes of samples 2, 3, and 5 [Fig. 2(b), (c), (d)] exhibit mixed distributions where the alkanes from higher plant wax predominate. The homologs >n-C24, with a strong odd-to-even carbon number predominance and maximum at n-C29 , are characteristic of plant wax (e.g. EGLrNTONand HAMILTON, 1963; KOLArTUKUDV and WALTON, 1972; SIMONEIT, 1975, 1978b). This distribution pattern correlates with an origin from predominantly grassland and forest

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884

BERND R. T. SmIo~,~xT,M. A. MAZLrREK,S. BRENNER,P. T. CRISe and I. R. KAPLAN

Table 2. Lipid yields and analytical results for the Guaymas Basin sediment samples n-AIkanes

n-Fatty acids

Sample No.

Concentration (p.g/g dry sed.)

1

24

1.5

2 3 5 7

1 3 5 18

3.0 6.0 1.8 1.4

CPI*

Pr/Ph'j" 0.6 1.2 0.1 1.1 0.5

n-Alkylmethylketones

Concentration (lag/gdry sed.)

CPI*

Concentration (lag/g dry sed.)

CPI*

30 90 2 135 24

7.5 7.8 15.3 5.8 7.6

3 7 1 45 2

2.2 3.1 2.0 2.5 2.3

* Carbon preference index summed from C~o to C36. t Pristane-to-phytane ratio.

terrigenous vegetation (CRANWELL, 1973). The homologs < n - C 2 4 reflect the marine component and consist of residues from primary production (n-C 17 and n-C~9; e.g. HAN a n d CALVIN, 1969) and from microbially altered algal detritus (maximum at n-C22 o r nC23; e.g. JOHNSON and CALDER, 1973; CRANWELL, 1973; HATCHER, SIMONEIT a n d GERCHAKOV, 1977). The n-fatty acids of all five samples exhibited bimodal distributions with strong even-toodd carbon number predominances, attributable to a mixed origin [Fig. 2(1)-0) ]. The homologs < / / - C 2 o , with the maximum at n-C~6 or n-C~s, are derived predominantly from marine autochthonous production (SIMONEIT, 1975, 1978b). The homologs > n-C2o, with the maximum a t n-C24 o r n-C26 , when considered with the n-alkanes > n-C24 , indicate an allochthonous terrigenous origin from higher plants (SIMONEIT, 1975, 1978b; HITCHCOCK and NICHOLS, 1971). Higher-plant fatty acids are present in all five samples and may be adsorbed on, or entrapped in, the fine clay particles (THoMPsoN and EGLINTON, 1978) that were transported to this marine basin. Ketones (Table 2) are significant components of the lipids and consist predominantly of the isoprenoids, with lesser amounts of the n-alkylmethylketones [Fig. 2(k)-(o)]. The principal isoprenoid is 6,10,14-trimethylpentadecan-2-one (Structure I, see Appendix); 6,10-dimethylundecan-2-one (II) is present at a lower concentration. Phytol from chlorophyll is the probable precursor of these compounds (SIMONEIT, 1973; IKAN, BAEDECKERand KAPLAN, 1973). The n-alkylmethylketones, C n H E n O , range from n = 11 to 33 and there are strong odd-to-even carbon number predominances > C22. The homologs >C22 indicate a terrigenous origin and their distributions are analogous to those for samples from the Black Sea (SIMONEIT,1978a). These compounds are probably derived from n-alkanes or n-fatty acids by microbial oxidation (ARPINO, 1973). The lipids of the five samples contain small amounts of the molecular markers characteristic of a terrigenous or marine biogenic origin. Steranes and sterenes are present only in trace amounts, in agreement with the absence of petroleum residues. The triterpenoidal markers, which appear to be derived mainly from bacteria (e.g. DEROSA, GAMBACORTA,MINALE and BU'LOCK, 1971 ; ROHMER, 1975), consist of 17fl(H)-hop-22(29)ene (diploptene, III, major component), hop-21(22)-ene (IV, minor), hop-17(21)-ene (V, minor), 17fl(H)-22,29,30-trisnorhopane (VI, minor), 17fl(H),21fl(H)-30-norhopane (VII, minor), 17fl(Hj'-hopane (VIII, major), and the series of extended 17fl(H)-hopanoic acids, C n H E n _ l o O 2 , ranging from n = 31 to 33 with n = 32 as the major homolog (IX). The relative distributions of the triterpenoids (based on the role 191 mass chromatogram) in

Organic geochemistryof recent sedimentsfromGuaymasBasin, Gulf of California a

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these samples are shown in Fig. 3. They consist of 17fl(H) homologs ranging from C27 to C35, with only a minor amount of C28 and large amounts of unsaturated analogs. The extended hopanes (> C31) are present as single C-22 diastereomers. The presence of the 17fl(H) stereomers and of the triterpenes indicates a recent biogenic origin for these molecular markers, because these compounds are present in living organisms. The virtual absence of the thermodynamically more stable 17ct(H) stereomers indicates that input of heavy petroleum components to these sediments has not occurred (DASTILLUNG and ALBRECHT, 1976; SIMONEITand KAPLAN, 1979). This can be compared with the example of recent sediment from the Southern California Bight [Fig. 3(f)], where the triterpanes consist predominantly of the 17~(H) homologs, and the extended hopanes (> C31, X) are present as 1 : 1 mixtures of the 22R and 22S diastereomers (SIMONEITand KAPLAN, 1979). There, the dominant homolog is 17~(H), 18~t(H), 2 lfl(H)-28,30-bisnorhopane (C28H48 , XI), which can be viewed as a molecular marker of Southern California petroleum (SIMONEITand KAPLAN, 1979; S E I F E R T , M O L D O W A N , SMITH and WHITEHEAD, 1978). Minor amounts of diterpenoids are present; these are probably derived from resinous higher plants (SIMONEIT, 1977). The following compounds were identified: dehydroabietic acid (XlI, major), dehydroabietin (XIII, minor) with a related analog (minor), simonellite (XIV, minor), retene (XV, major), and a homoditerpane (possibly XVI, trace). Their

I 40

BERNDR. T. SIMONEIT,M. A. MAZUREK,S. BRENNER,P. T. CRISPand I. R. KAPLAN

886

relative distributions are indicated in Fig. 3. Further possible molecular markers of bacterial lipids are alkylcyclohexanes, which may be derived from cyclohexylalkanoic acids found in various bacteria (e.g. DEROSA et al., 1971). Samples 1 and 7 contain a series of alkylcyclohexanes, C, H2, (XVII) ranging from n = 15 to 21, with a m a x i m u m at n = 19, and two isomeric series of alkylmethylcyclohexanes, C, H2n (XVIII) ranging from n = 16 to 21, with a m a x i m u m at n = 20. Alkylcyclohexanes were reported in an oxic nannoplankton ooze containing mainly bacterial lipids (SIMONEITand MAZUREK,1978), and a monocyclic hydrocarbon (C2oH40) was identified in algal mat and sediment from Laguna Mormona, Baja California (CARDOSO, BROOKS, EGLINTON, GOODFELLOW, MAXWELL and PmLP, 1976). Polynuclear aromatic hydrocarbons (e.g. perylene) were not present at significant concentrations in the G u a y m a s Basin sediment.

Humates and kerogens

Analytical results for the humates and kerogens are given in Table 3. The atomic H/C and N/C ratios for the humates are characteristic of aliphatic algal material, although the N/C ratios are somewhat low (STUERMERet al., 1978). The 613C values range from - 19.6 to -19.9%o and are characteristic of a marine origin (NIssENBAUM and KAPLAN, 1972; DEGENS, 1969). The kerogens exhibit atomic H/C and N/C ratios also typical of aliphatic material; however, the N / C ratios again appear low (STUERMER et al., 1978). The 3t3C values range from - 2 0 . 8 to -21.1%o and are characteristic of a marine origin (KAPLAN, 1975; DEGENS, 1969). In a plot of H / C vs 313C, these data for the humates and kerogens cluster in the marine domain as was described by STUERMER et al. (1978). Thus, the bulk of the organic carbon of these samples is of an autochthonous marine origin.

C1 to C8 hydrocarbons

Core sections taken from subbottom depths greater than ~2.8 m had a strong petroliferous odor. Two sections (samples 5 and 6) from the petroliferous zone and one (sample 4) from above the zone were analyzed for Ct to C 8 hydrocarbons (Table 4). As the sediments were stored at - 2 0 ° C under the same conditions until analysis, any loss of volatile hydrocarbons during storage should have been approximately equal for the three

Table 3. Analysesof humates and kerogens in the Guaymas Basin sediment samples

Humates Sample No. 1 2 3 7

Concentration Yoof (llg/g dry sed.] org.C 9000 17000 19000 12000

19 n.d.:~ 29 15

Kerogens

H/C ratio*

N/C ratio*

613C (°/oo)t

H/C ratio*

N/C ratio*

613C (%o),

1.5 n.d. 1.4 1.7

0.092 n.d. 0.104 0.080

- 19.6 -19.9 - 19.9 -19.6

1.6 1.6 1.6 1.8

0.075 0.074 0.078 0.051

- 21.0 -20.8 -21.1 -20.9

* Based on data from the Microanalytical Laboratory, University of California, Berkeley. t Versus Chicago PDB standard. :!: Not determined.

Organic geochemistry of recent sediments from Guaymas Basin, Gulf o f California

Table 4.

887

C~ to C 8 hydrocarbon analyses of the Guaymas Basin sediment samples

Concentration (ng/g dry sediment) Hydrocarbon* Methane Ethane Ethylene Propane Propylene Isobutane n-Butane 2,2-Dimethylpropane

2-Methylbutane n-Pentane

Cyclopentane 2,2-Dimethylbutane

2,3-Dimethylbutane 2-Methylpentane 3-Methylpentane Methylcyclopentane n- Hexane

Cyclohexane Total C7 Total C 8 Total C1 to C8 C, ( C 2 + C 3)

ratio

C1 (C, + C 2 + C 3 + C4)

~13C (°/oo)t

Sample 4

Sample 5

Sample 6

(2.51 2.58 m)

(2.94--2.99 m)

(3.38--3.45 m)

7520 56 1.3 98 0.7 967 532 22 2670 1210 69 24 246 323 323 466 328 128 497 32 15493

6350 40 0.8 113 0.1 1180 657 6.4 1670 743 88 3.8 33 80 74 357 162 71 80 10 11709

2190 11 0.05 3.6 0.02 5.2 0.7 2.4 3.8 0.3 0.05 3.3 32 0.8 20 113 1760 3.1 30 44 4223 149

ratio

0.99 - 73.5

48 0.82 - 68.8

41 0.76 - 70.5

(for C H 4 only)

* Identification based on GC retention time only.

t Versus Chicago PDB standard.

sections. Therefore, although the data may not be quantitative, we believe they are comparable. Samples 5 and 6 contain approximately equal concentrations of C1 to C 8 hydrocarbons, while sample 4 has much lower concentrations. Quantities of C t to C8 alkanes were measureable in all three samples. The unsaturated gases ethylene and propylene, usually associated with the microbial decomposition of organic matter, were present only in trace quantities. The t~13C values for the methane in the three sections ( - 6 9 to -73%o) are typically biogenic (DEGENS, 1 9 6 9 ; KAPLAN, 1 9 7 5 ; BERNARD, BROOKSand SACKETY, 1976). Stable carbon isotopes of the C 2 to Ca hydrocarbons could not be determined due to their low concentrations. Biogenic hydrocarbon gases usually have C1/(C2 +C3) ratios greater than 1000, while those of petrogenic origin have ratios less than 50 (BERNARD e t al., 1976). The Guaymas Basin C~/(C 2 +C3) ratios lie between 149 and 41 and thus indicate a mixed input of biogenic (C1) and petrogenic (C2 to Ca) hydrocarbons.

888

BERND R. T. SIMONEIT,M. A. MAZUREK,S. BRENNER,P. T. CRISP and I. R. KAPLAN

CONCLUSIONS D u r i n g the p a s t 2000 years, the G u a y m a s Basin h a s r e c e i v e d a m i x e d a n d v a r i a b l e i n p u t o f o r g a n i c d e t r i t u s , (i) f r o m p r i m a r y a u t o c h t h o n o u s p r o d u c t i o n a n d m i c r o b i a l a l t e r a t i o n , a n d (ii) f r o m a l l o c h t h o n o u s t e r r i g e n o u s sources. T h e b u l k o f the o r g a n i c m a t t e r is, h o w e v e r , o f an a u t o c h t h o n o u s o r i g i n a n d d i a g e n e t i c a l l y i m m a t u r e . T h e h i g h g e o t h e r m a l h e a t flow o f the b a s i n a p p e a r s to h a v e g e n e r a t e d s o m e g a s o l i n e - r a n g e (C 2 to Ca) h y d r o c a r b o n s at d e p t h t h a t a p p e a r to be m i g r a t i n g t h r o u g h the s e d i m e n t layers. T h e lipids, h u m a t e s , a n d k e r o g e n s o f the s e d i m e n t s h a v e n o t b e e n a l t e r e d by this g e o t h e r m a l stress, a n d the m e t h a n e is o f a p r e d o m i n a n t l y b i o g e n i c origin. Acknowledgements--We thank the Scripps Institution of Oceanography and the crew of the R.V. Melville for the core, Mr E. RUTHfor GC-MS analyses, Mr B. ROHRaACKand Mr D. WINTERfor stable carbon isotope analyses, and Mr B. LATNERfor assistance in gas analyses. Financial assistance from the Department of Energy Bureau of Land Management (Grant No. EY-76-S-03-0034, P.A. 134) and the National Aeronautics and Space Administration (Grant No. NGR 05-007-221) is gratefully acknowledged. One of the authors (P.T.C.) received support during this study from a Commonwealth Scientific and Industrial Research Organization (Australia) Postdoctoral Studentship. Note added in prooJ---Three additional samples (30G, subbottom depths: 1.23-1.29m, 2.5%2.65m and 3.31 3.37 m) were analyzed for C1-C7 volatile compounds at Woods Hole Oceanographic Institution (J. WHELAN, unpublished results). The results were comparable, showing an increase in gasoline range hydrocarbons versus depth. The Deep Sea Drilling Project--IPOD drilled Site 64-481 about 8 km southwest of Site 30G, also in the northern rift of the Guaymas Basin. The same odor and C1-C7 gas composition was encountered at a depth of about 150-170 m between the two upper sills of Site 481. These gasoline range hydrocarbons were formed by the thermal stress from sills and/or dikes which intruded into the unconsolidated Recent marine sediments. REFERENCES ARPINO P. (1973) Les lipides des srdiments lacustres l~ocrnes. Thrse, I'Universite Louis Pasteur de Strasbourg, France. BERNARDB. B., J. M. BROOKSand W. M. SACRETT(1976) Natural gas seepage in the Gulf of Mexico. Earth and Planetary Science Letters, 31, 48-54. BYRNEJ. V. and K. O. EMERY(1960) Sediments of the Gulf of California. Geological Socie O, of America, Bulletin, 71,983-1010. CARDOSOJ., P. W. BROOKS,G. EGLINTON, R. GOODFELLOW,J. R. MAXWELLand R. P. PHILP (1976) Lipids of recently-deposited algal mats at Laguna Mormona, Baja California. In: Environmental biogeochemistry, J. O. NRIAGU,editor, Ann Arbor Science Publishers, 149-174. CRANWELL P. A. (1973) Chain-length distribution of n-alkanes from lake sediments in relation to post-glacial environmental change. Freshwater Biology, 3, 259-265. DAST1LLUNGM. and P. ALBRECHT(1976) Molecular test for oil pollution in surface sediments. Marine Pollution Bulletin, 7, 13-15. DEGENS E. T. (1969) Biogeochemistry of stable isotopes. In: Organic geochemistry--methods and results, G. EGLINTONand M. T. J. MURPHY, editors, Springer-Verlag, 304-329. DEROSA M., A. GAMBACORTA, L. MINALE and J. D. BU'LOCK (1971) Bacterial triterpanes (thermophyllics). Chemical Communications, 1971, 619-620. EGLINTON,G. and R. J. HAMILTON(1963) The distribution of alkanes. In: Chemicalplant taxonomy, T. SWAIN, editor, Academic Press, 187-217. GOLDHABERM. B. (1974) Equilibrium of dynamic aspects of the marine geochemistry of sulphur. Ph.D. Thesis, University of California, Los Angeles, 399 pp. HAN J. and M. CALVIN(1969) Hydrocarbon distribution of algae and bacteria, and microbiological activity in sediments. Proceedings of the National Academy of Science, U.S.A., 64, 436-443. HAN J., E. D. MCCARTHY,M. CALVINand M. H. BENN(1968) Hydrocarbon constituents of the blue-green algae Nostoc muscorum, Anacystis nidulaus, phormidium luridum and Chloroglea fritschii. Journal of the Chemical Society (C), 1968, 2785-2791. HATCHERP. G., B. R. SIMONErrand S. M. GERCHAKOV(1977) The organic geochemistry of a Recent sapropelic environment: Mangrove Lake, Bermuda. In: Advances in organic geochemistry 1975, R. CAMPOSand J. GONI, editors, Enadimsa, 469-484.

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HITCHCOCK C. and B. W. NICHOLS (1971) Plant lipid biochemistry, Academic Press, 387 pp. IKANR., M. J. BAEDECKERand I. R. KAPLAN(1973) Ct 8-isoprenoid ketone in Recent marine sediment. Nature 244, 154~155. JOHNSON R. W. and J. A. CALDER (1973) Early diagenesis of fatty acids and hydrocarbons in a salt marsh environment. Geochimica et Cosmochimica Acta, 37, 1943 1955. KALIL E. K. (1976) The distribution and geochemistry of uranium in Recent and Pleistocene sediments. Ph.D. Thesis, University of California, Los Angeles, pp. 268. KAPLAN I. R. (1975) Stable isotopes as a guide to biogeochemical processes. Proceedings Of the Royal Society of London, BI89, 183-211. KAI'LAN I. R., J. W. SMITH and E. RUTH (1970) Carbon and sulfur concentration and isotopic composition in Apollo 11 lunar samples. In: Proceedings of the Apollo 11 Lunar Science Con/erence Geochimica et Cosmochimica Acta, Supplement 1, Vol. 2, Pergamon Press, 1317-1329. KOLATTUKUDY P. E. and T. J. WALTON (1972) The biochemistry of plant cuticular lipids. In: Progress in the chemistry of/ats and other lipids, R. T. HOLMAN,editor, Pergamon Press, Vol. 13, pt. 3, 121 175. McAULLIEE C. (1969) Determination of dissolved hydrocarbons in subsurface brines. Chemical Geology, 4, 225 233. MclvF.R R. D. (1973) Hydrocarbon gases from canned core samples, sites 174A, 176 and 180. In : Initial report.~ of the deep sea drilling project, Vol. XVIII, L. V. D. KULM, R. V. HUENE et al., editors, U.S. Government Printing Office, Washington, DC, 1013-1014. NISSENBAUMA. and I. R. KAPLAN(1972) Chemical and isotopic evidence for the in situ origin of marine humic substances. Limnology and Oceanography, 17, 570 582. ORt) J., T. G. TORNABENE,D. W. NOONERand E. GELPI (1967) Aliphatic hydrocarbons and fatty acids of some marine and freshwater microorganisms. Journal of Bacteriology, 93, 1811-1818. RDHMERM. (1975) Triterpenoides de procaryotes. Ph.D. Th6se, l'Universit6 Louis Pasteur de Strasbourg, France, 100 pp. SEIFERT W. K., J. M. MOLDOWAN,G. W. SMITHand E. V. WHITEHEAD(1978) First proof of structure of a C28pentacyclic triterpane in petroleum. Nature, 271,436 437. SIMONHT B. R. (1973) Identification of isoprenoidal ketones in Deep Sea Drilling Project core samples and their geochemical significance. In : Initial reports of the deep sea drilling project, Vol. XXI, R. E. BURNS, J. E. ANDREWS et al., editors, U.S. Government Printing Office, Washington, DC, 909 923. SIMONEIT B. R. T. (1975) Sources of organic matter in oceanic sediments. Ph.D. Thesis, University of Bristol, England, 300 pp. SIMONEIT B. R. T. (1977) Diterpenoid compounds and other lipids in deep-sea sediments and their geochemical significance. Geochimica et Cosmochimica Acta, 41,463 476. SIMONEIT B. R. T. (1978a) Organic geochemistry of terrigenous muds and various shales from the Black Sea, DSDP, Leg 42B. In: Initial reports o f the deep sea drilling project, Vol. XLII, Pt. 2, D. Ross, Y. NEPROCHNOV et al., editors, U.S. Government Printing Office, Washington, DC, 749-753. SIMONEEr B. R. T. (1978b) Terrigenous and marine organic markers and their input to marine sediments. Proceedings of the symposium on the organic geochemisto' of the deep sea drilling project sediments. E. W. BAKER, editor, Science Press (in press). SIMONEIT B. R. T. and I. R. KAPLAN (1979) Triterpenoids as molecular indicators of paleoseepage in Recent sediments of the Southern California Bight. Marine Pollution Bulletin (in press). SIMONEIT B. R. T. and M. A. MAZUREK(1978) Lipid geochemistry of Cretaceous sediments from Vigo Seamount, DSDP/IPOD Leg 47B. In: Initial reports O['the deep sea drilling project, Vol. XLVII, Pt. 2, W. B. F. RYAN, J. C. SmUETet al., editors, U.S. Government Office, Washington, DC (in press). SrUERMERD. H., K. E. PETERSand I. R. KAPLAN(1978) Source indicators of humic substances and protokerogen : Stable isotope ratios, elemental compositions and electron spin resonance spectra. Geochimica et Cosmochimica Acta, 42, 989-997. THOMPSONS. and G. EGLINTON (1978) The fractionation of a Recent sediment for organic geochemical analysis. Geochimica et Co,~mochimica Acta, 42, 199-207. VAN ANDELT. and G. SHOR(1964) Marine geology of the Gulf of California. Memoir O/the American Association of Petroleum Geologists, 3, Tulsa. YOUNGBLfX)DW. W., M. BLUMER,R. L. GUILLARDand F. FIORE(1971) Saturated and unsaturated hydrocarbons in marine benthic algae. Marine Biology, 8, 190 201.

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APPENDIX

I

6,10,14- f rimethylperrtodec - 2 - one, C18H360

TIT cliploptene, C3oH5o

~]- hop-17(21 )-ene,C30H5o

~]I

17~ (H)-norhopone, CzeH5o

~

]~r hop-21 (22)-ene, C30H50

17/~ (H}- trisnorhopone, C27H46

17fl(H)-hopane, C30H52

.__~COOH

TX- 17#(H), 21~ (H)bishomohoponoic ocid, C32H5402

17(x(H),18c((H), 21,6'(H)28, :30 - bisnorhopone,

C28H48

~ 0 11- 6,10-dimethylundecon-2-one, C13 H260

X

extended 17cc(H)hopones

XIT dehydroobietic o cid, C20H2802

891

X11I dehydroabietin, Cl9 H2e

simoneflite, C1gH24

retene, C18H18

~ XVll

homoditerpone, C21H3e

"CnH2n +1 n = 9.16

olkylcyclohexones

XVll!

olkylmethylcyclo hexones