54. C1-C8 HYDROCARBONS IN SEDIMENTS FROM THE LOWER CONTINENTAL RISE,DEEP SEA DRILLING PROJECT SITE 6031

Jean K. Whelan and Christine Burton, Woods Hole Oceanographic Institution 2

ABSTRACT

Small amounts of C1-C8 hydrocarbons were detected in continental rise sediments from DSDP Site 603. Organic-carbon-lean sections contained only C1-C3 compounds believed to have migrated from organic-carbon-rich sections.Heavier (C4-C8) hydrocarbons were found only in organic-carbon-rich sections. Restricted and sporadic distribution ofC4-C6 compounds in 0-1100 m sub-bottom sediments suggest low-temperature (<20°C) biological/chemical genera-tion processes. Increased C4-C8 concentrations and complexity, including unusually high levels of xylene, were detectedin two deeper Cretaceous sections (603-34-2, 134 cm and 603-81-3, 120 cm). This behavior, which was not observed in17 other samples from sub-bottom depths greater than 1100 m, is similar to that observed in immature surface sedi-ments from the geothermally active Guaymas Basin (Gulf of California) area.

INTRODUCTION

Small amounts [parts per billion (ppb)] of light hydro-carbons have been detected in surface and DSDP sedi-ments from many areas. In immature fine-grained sedi-ments, traces of these compounds are produced in situby a combination of low-temperature (< 30°C) chemicaland biological processes, which could occur near the sed-iment/water interface before burial (Whelan, 1984; Whe-lan and Hunt, 1983). Migration of these hydrocarbonslarger than propane (C3) is minimal, being on the orderof centimeters, between Cretaceous interbedded greenand black shale layers recovered from the South Atlan-tic, DSDP Leg 75 (Jasper et al., 1984; Whelan et al.,1985).

Leg 93 sediments provide an opportunity to furtherexamine small-scale migration of these light hydrocar-bons between interbedded organic-carbon-rich and -leansediments. In addition, examination of several closelyspaced samples from various depths may allow us to dif-ferentiate migration from thermal generation processesin the 25-35°C temperature range. Earlier work showsthat in this temperature range, light hydrocarbons beginto increase in both amount and complexity above levelsin surface sediments (Whelan and Hunt, 1983).

EXPERIMENTAL

The methods used in this work have been described in detail else-where (Whelan, 1984). Briefly, frozen sediment is placed in a stainlesssteel vessel equipped with a septum. After distilled water and heliumare added, the vessel is sealed, shaken, and heated at 90°C for 30 min.to drive volatile compounds into the gas phase. The compounds re-leased are analyzed by gas chromatography and peak areas are mea-sured using an electronic integrator.

RESULTS AND DISCUSSION

Except for samples at 160 and 1130 m sub-bottom,the amounts of sorbed methane in Holes 603B and 603C

van Hinte, J. E., Wise, S. W., Jr., et al., Init. Repts. DSDP, 93: Washington (U.S.Govt. Printing Office).

2 Address: Chemistry Department, Woods Hole Oceanographic Institution, Woods Hole,MA 02543.

1983). (Throughout the remainder of this chapter, theterm "biological" will also include any chemical pro-cesses occurring at temperatures of less than 20°C; theseprobably occur together with and are not distinguish-are generally low (Fig. 1). Amounts of C1-C5 hydrocar-bons from 0 to 1600 m sub-bottom are shown in Table 1and Figure 1 and, on an expanded scale, Figure 2. Meth-ane gas pockets were found throughout these holes, par-ticularly in Hole 603B. The methane measurementsrepresent residual gas remaining in these cores afterfreezing, sectioning, and storage. Thus, methane con-centrations in Table 1 are qualitative only. However,based on previous work with surface sediments (Whe-lan, 1984; Whelan and Hunt, 1983; Whelan et al., 1985,and references cited therein), the amounts of sorbedmethane retained by anoxic sediments are generallyhigher than for more oxic sediments not exposed to sig-nificant methanogenic activity.

Figure 2 shows a magnification of the C1-C3 com-pounds where the methane is generally accompanied bytraces of ethane and propane that appear to be covari-ant with methane. (The magnification shows the covari-ance, which cannot be seen in Fig. 1). This behavior istypical of many immature, gassy DSDP sediments. Thesesmall amounts of ethane and propane are probably mi-crobiologically produced near the sediment/water inter-face (Oremland, 1981). In deeper horizons, below 900 m,they may be produced by low-temperature thermal pro-cesses (Rice and Claypool, 1981). However, no generalincrease of C2 and C3 with depth is observed at Site 603(Fig. 2), as should be seen if production were occurringvia a thermal maturation process (Rice and Claypool,1981).

A few sections of these holes showed traces of C6-C8compounds (Table 2). In the shallower sections to 1100m, the C6 and C8 constituents are of limited compounddistribution (consisting of «-hexane and w-heptane onlyat 969 m sub-bottom), suggesting that these compoundswere produced by biological/low-temperature chemicalprocesses in shallower sections, as occurs, for example,in surface cores from the Peru Shelf (Whelan and Hunt,

1231

J. K. WHELAN, C. BURTON

0

100

200

300

400

500

600

700

800

900

1000

1100

500 1500 2500 50 100 150

πg hydrocarbon/g dry wt. sediment (ppb)

20 40 60 20 40 60 5 10 15 10 20 30 40 50 13 26 39 52

1300

1400

1500

1600

C1

i i i i

C2 C3 /C4 nC4 /C5

l 1 1 1 1

πC5

Figure 1. C1-C5 alkanes sorbed on Site 603 sediments. Abbreviations: methane (Cl); ethane (C2); propane (C3); isobutane (/C4); n-butane («C4);

/'sopentane (/C5); n-pentane (nC5).

Table 1. Concentrations of C1-C5 alkanes at DSDP Site 603.

Sample(interval in cm)

Hole 603C

10-1, 5020-1, 5025-1, 50

Hole 603B

16-1, 1416-1, 12716-2, 2716-2, 13816-3, 6328-4, 3529-3, 12033-2, 11734-1, 5334-2, 13436-3, 12236-3, 12537-4, 12037-4, 12437-4, 12638-3, 12542-1, 6542-1, 7342-1, 8043-4, 453-4, 11959-4, 12066-2, 12066-2, 12866-2, 14781-3, 120

Sub-bottomdepth (m)

77.8164.9212.9

965.5966.7967.2968.3969.0

107810851121.211281130.341149.721149.751160.21160.241160.261167.751197.851197.9311981209.31306.51364.41426.51426.61426.81562.4

Description

Silty clay olive-greenSilty-sideriteSilty clay olive green

Red/beigeBrown and red/beigeDark grayDark grayRed/beigeDark gray-clay/siltDark red-clay/siltGreen quartz/micaDark gray carbonaceous/clayDark gray carbonaceous/clayDark gray carbonaceous/clayDark gray carbonaceous/clayDark gray/greenOrg-rich clay/pyrDark gray green clayBioturb. clayLayers-green and grayDark grayLayers-green and grayRed brownDark gray-nanno clayGrn gray sandstoneWhite light grayGreen to dark grayLight grayGray

C o r g (<Vo)

ndndnd

<O.l<O.l<O.l<O.l<O.l<O.l<O.l

410.513.6

110.31.10.3

<O.l0.7-1.2

2.50.7-1.2

<O.l0.20.6

<O.lnd

<O.l0.4

Cl

46708

95

245266351247

91173787

16303410

2451715547931840807625106263

75830

ng HC/g dry wt.

C2

36.15.5

135.65.04.42.302.25

68178

4.8113.71.85.3

1.02

1141.80.74.15.605.42.8

C3

1.62.82.0

3.921.51.3000.61.2

3485

1.22.71.21.61.800

411.8001.62.5001.5

sediment

C4

01.10

00000000

4898

0000.8000

431.50000004.6

C5

1.400

00000000

2950

0000000

1122.5000000

13

1983). (Throughout the remainder of this chapter, theterm "biological" will also include any chemical pro-cesses occurring at temperatures of less than 20°C; theseprobably occur together with and are not distinguish-able from strictly biological processes, as discussed in

detail in Whelan, 1984, and Whelan and Hunt, 1983.)In contrast, a much larger diversity of compounds iscommonly observed in sediments below 1100 m sub-bot-tom, suggesting a thermal origin. The geothermal gradi-ent at this site is 2.19°C per 100 m. If it is assumed that

1232

C1-C8 HYDROCARBONS, SITE 603

ng hydrocarbon/g dry wt. sediment100 200 300 400 10 20 30 40 2 4

Figure 2. Expansion of C1-C3 hydrocarbon profiles. Dashed lines showunit boundaries: I is Pleistocene to Eocene claystone; II is Eoceneclaystone; III is lower Paleogene variegated claystone; IV is Creta-ceous claystone (including black shales); V is Cretaceous laminatedmarl and bioturbated limestone.

bottom waters average 4°C, then current geothermal tem-peratures would be about 30°C at 1150 m sub-bottom.The sediments show no evidence from sedimentologicalor pyrolysis data (Meyers et al., this volume) of expo-sure to higher temperatures in the past. Thus, any ther-mal processes operating at this site must occur at lowtemperatures (as compared to about 50°C, the minimumgenerally accepted as representing the start of the oil-generation window; Hunt, 1979, p. 101).

The Cl to C8 profiles of specific intervals (Tables 1and 2) are presented here with a discussion of possiblesources for the compounds.

Surface (78-213 m sub-bottom) (Pleistocene)

Cl and C3 hydrocarbons were detected in five sec-tions with methane levels 10 to 100 times greater thanthose of ethane and propane. This is typical of sorbedhydrocarbons in anoxic sediments that have been affect-ed by methanogenic bacteria (Whelan, 1984; Whelan andHunt, 1983). The absence of any C6-C8 compounds andonly restricted occurrences of n-C4 and n-C5 support abiogenic rather than a thermogenic source for these com-pounds. This limited compound distribution is typicalof sediments subjected only to biological processes andnot exposed to thermal hydrocarbon generation or tomigrated or anthropogenic hydrocarbons. The currentgeothermal temperature at the bottom of this sequence(213 m sub-bottom) can be calculated to be about 8°C,which is consistent with the absence of hydrocarbonstypical of thermal generation. Pore water sulfate levelsdrop to values below 2 mM by 17 m sub-bottom so thatmicrobiological methane production is geochemically pos-sible in all deeper sediments below this depth, assumingother nutrients are adequate (Rice and Claypool, 1981).

Methane is about an order of magnitude higher at165 m sub-bottom than in sediments above and below—at 78 and 213 m sub-bottom. These data suggest that thesediment at 165 m sub-bottom (603C-20-1, 50-54 cm)may have been subjected to greater influence of methano-gens than adjacent sections.

Samples 603B-16-1, 14-16 cm to 603B-16-3, 63-65 cm(965.5-969.0 m sub-bottom) (Eocene)

These radiolarian claystones show large color varia-tions not related to their organic carbon content (<0.1%).Organic carbon is too low for significant light hydrocar-bon production from thermogenic or biogenic sources.Thus, the small amounts of methane, ethane, and pro-pane in the five sections examined are probably migrated,a conclusion supported by comparable levels of thesecompounds in all sections. Compounds larger than C3are not present. This observation is consistent with pre-vious work on alternating green and black shale (organ-ic-lean and -rich) layers from Cretaceous shales from theSouth Atlantic (DSDP Leg 75), where it was concludedthat only Cl and C2 appeared to be consistently migrat-ing from organic-rich into adjacent organic-lean sections(Jasper et al., 1984; Whelan et al., 1985). In the currentwork, propane also appears to have undergone some mi-gration throughout the section.

Samples 603B-28-4, 35-36 cm and 603B-29-3,120-124 cm (1078 and 1985 m sub-bottom,respectively) (Paleogene)

Both of these samples are terrigenous silty claystonescontaining less than 0.1 °7o organic carbon. Only tracesof methane occur in the shallower sample, and onlyC1-C3 were detected in the deeper. No higher molecularweight compounds (C4-C8) were found. Methane is ap-proximately 10 times less than in the 965-969 m sub-bottom section described previously.

Samples 603B-33-2, 117-121 cm to 603B-36-3,125-126 cm (1121.1-1149.75 m sub-bottom)(Cretaceous-Cenomanian-Turonian)

Five samples from this section varied in color fromgray to dark gray with moderate to very high (1-13.6%)organic carbon content. Maximum organic carbon andlight hydrocarbon values occur in two samples near thecenter of the section. Variations in C1-C5 hydrocarbonsbetween organic-carbon-rich and -lean sections are stillapparent when the data are normalized to organic car-bon (Table 3), although the differences have been reducedsomewhat. No C4-C8 compounds were detected in Sam-ples 306B-33-2, 117 cm (6.8 m sub-bottom, above thericher intervals) or in 306B-36-3, 122 cm or 306B-36-3,125 cm (19.4 m sub-bottom, below the rich intervals).Thus, vertical migration of the C4 + compounds fromrich to lean sections has not occurred over distances of afew meters, consistent with results found previously overmuch shorter vertical distances at other sites.

The three leaner sections contain moderate amountsof organic carbon (1-4%), which also might be capableof undergoing in situ light hydrocarbon generation. How-ever, only C1-C3 compounds are found in these inter-vals in levels comparable to those in the more organic-

1233

J. K. WHELAN, C. BURTON

Table 2. Content of C6-C8 hydrocarbons at DSDP Site 603.

Compounds

Alkanes

Sum C6Sum C7SumC8

Aromatics

Tol and benzXylenes

77.8

000

00

Individual compounds8

CP23DMB2MP3MP«C6MPCCH2MH22DMP24DMP1T3DMCP1T2DMCP1C2DMCPnCl3EPMCHBENZTOL234TMPDMH b

«C81C2T3TMCP1T2DMCHETBENZm&p XYLoXYL

0.830000000000000000000000000

969

1.62.40

00

00001.6000000002.43000000000000

1128

198.92.8

00

0.391.18.51.11.15.91.60.5600.562.10.850.980.662.20.98002.00.71000000

1130

27125.2

00

1.21.6

11.21.51.29.72.10003.61.41.703.81.60001.53.700000

Sample depths (m)

1160

0.6500

00

000.6500000000000000000000000

1197.93

443.61.8

5.8110

210.81371.12.21.61.31.10.5300001.400.641.44.301.8000

484418

1198.0

6.900

00

006.9300000000000000000000000

1306.5

4.49.38.4

6.80

00.491002.900001.34.30.94002.806.83.9002.12.3000

1426.6

4.01.50

00

001.5002.50000000001.50000000000

1562

1717.73.1

012

00.884.31.12.26.2121.1002.54.20.92.42.14.50002.001.107.34.90

a Abbreviations: cyclopentane (CP); 2,3-dimethylbutane (23DMB); 2-methylpentane (2MP); 3-methylpentane(3MP); w-hexane («C6); methylcyclopentane (MCP); cyclohexane (CH); 2-methylhexane (2MH); 2,2-di-methylpentane (22DMP); 2,4-dimethylpentane (24DMP); l-trans-3-, l-trans-2-, and l-cis-2-dimethylcyclo-pentane (1T3DMCP, 1T2DMCP, and 1C2DMCP, respectively); w-heptane («C7); 3-ethylpentane (3EP);methylcyclohexane (MCH); benzene (BENZ); toluene (TOL); 2,3,4-trimethylpentane (234TMP); dimethyl-hexane (DMH); n-octane (nC8); l-cis-2-trans-3-trimethylcyclopentane (1C2T3TMCP); l-trans-2-dimethylcy-clohexane (1T2DMCH); ethylbenzene (ETBENZ); m- and p-xylene (m&p XYL); o-xylene (o XYL).Total for all isomers.

Table 3. C1-C5 hydrocarbons—normalization to organic carbon.

Sample(interval in cm)

33-2, 11734-1, 5334-2, 13436-3, 12236-3, 125

C o r g (*>

410.513.611

Methane

21.8155.0224.2245.0171.0

ng HC/g C o r g

Ethane

1.26.5

13.14.8

10.7

Propane

0.33.26.21.22.7

n-C4

0.04.67.20.00.0

n-C5

0.02.83.70.00.0

lean interval from 965-969 m sub-bottom, discussedpreviously. Thus, it seems probable that if in situ lighthydrocarbon generation did take place in these samples,it was limited to the C1-C3 range.

Samples 603B-37-4, 120-122 cm to 603B-38-3,125-132 cm (1160.2-1167.75 m sub-bottom)(Cretaceous-Albian-Cenomanian)

Of the four claystones examined, three contain lessthan 0.3% organic carbon. The C1-C3 compounds in

the section may represent migrated compounds, as dis-cussed previously for other organic-carbon-lean sections.Sample 37-4, 124-125 cm contains more organic carboncontent (1.1%) and pyrite lenses. However, levels of C l -C3 are similar to the other three samples, suggesting mi-gration and equilibration of these three low-molecular-weight compounds throughout this section. The richersample contains 0.8 ng/g of /sobutane, 0.6 ng/g of2-methyl pentane, and no other C4+ compounds. Therestricted distribution suggests that these compounds werebiologically produced. The absence of these two com-pounds only 2-4 cm above and below shows that C4 andC6 compounds have not migrated vertically out of theorganic-carbon-rich section.

Samples 603B-42-1, 65-67 cm to 603B-43-4, 0-4 cm(1197.85-1209.3 m sub-bottom)(Cretaceous-Aptian-Albian)

Four samples were examined—three gray to dark graylayers are within 20 cm of each other, whereas the fourth

1234

C1-C8 HYDROCARBONS, SITE 603

red brown layer is 11.3 m sub-bottom deeper. The graylayers all contain 0.7 to 1.2% organic carbon with thecenter layer containing the highest amount. Levels of Cland C2 in all of these are about equal, with the methanebeing about the same as in the 1160 m sub-bottom sec-tion and considerably lower than in some other organic-carbon-rich intervals (Table 1). These data are consistentwith diffusion of Cl and C2 throughout the section. Thisinterpretation is supported by approximately equal lev-els of Cl and C2 in the organic-carbon-lean ( < 0 . 1 %organic carbon) section at 1209 m sub-bottom.

The center two sections of this interval (603B-42-1,73 cm and 603B-42-1, 80 cm, Tables 1 and 2) containC3+ compounds. The 603B-42-1, 80 cm sample showsa restricted hydrocarbon distribution consisting of a ho-mologous series of /soalkanes—/sobutane, zsopentane,and /sohexane (2MP in Tables 1 and 2). The limited dis-tribution suggests the same biogenic source as for Sam-ple 603B-37-4, 124-125 cm at 1160.24 m, which con-tains an almost identical distribution. The possibility thatthese compounds have diffused in from the richer inter-val 7 cm above (603B-42-1, 73-75 cm) is unlikely be-cause the shallower interval contains slightly more A2-pen-tane than /-pentane, whereas the deeper interval containsonly /-pentane. The diffusion coefficient of iso-C5 is alittle higher than for «-pentane (Sahores and Witherspoon,1970), but not enough to account for such a large fraction-ation over these short distances. Thus, it is concludedthat the C5 + fraction (which is fairly complex in Sam-ple 603B-41-1, 73-75 cm) is not migrating significantlyin these sediments, even over distances as small as 7 cm.

Because of the apparent nondiffusion of C5-C8 hy-drocarbons in this interval, it is proposed that the com-plex light hydrocarbon mixture in Sample 603B-42-1,73-75 cm is either thermogenic in source or caused bysome migration process other than diffusion. The pres-ence of aromatic compounds, benzene, toluene, and rel-atively large amounts of xylene, suggest that this mix-ture was formed at a relatively high temperature, as foundfor the Guaymas Basin samples from the Gulf of Cali-fornia (Whelan and Hunt, 1982). Alternatively, migra-tion of light hydrocarbons favors the more water solublearomatic over the less soluble aliphatic hydrocarbons(Thompson, 1979). There is not evidence in the sedi-mentological record to suggest higher paleotemperaturesfor this interval (see site chapters, this volume). Thus,some sort of localized lateral migrational process is sug-gested, possibly similar to that found in surface organic-carbon-rich sediments from the Guaymas Basin (Whe-lan and Hunt, 1982). Such a process requires that adja-cent sediments received a source of heat at some time inthe past. Alternatively, petroleum hydrocarbons can mi-grate considerable distances (sometimes hundreds of miles)from petroleum sources or reservoirs through fault orfracture systems.

Samples 603B-66-2, 120-123 cm to 603B-66-2,147-150 cm (1426.5-1426.8 m sub-bottom)(Cretaceous-Hauterivian)

These three samples contain less than 0.1% organiccarbon and small amounts of C1-C3 hydrocarbons as-

sumed to have migrated into this section. The amountsare comparable to those in other organic-carbon-leanintervals of this hole, as discussed previously.

Sample 603B-81-3, 120-124 cm (1524.4 m sub-bottom)(Cretaceous-Valanginian)

This sediment is a nannofossil claystone/limestone.Sediments 18 cm below this section contain a large woodchunk and wood fragments (see site chapters, this vol-ume). Organic carbon is moderate to low (0.4%). How-ever, the section contains a complex series of C4-C8 hy-drocarbons suggesting a thermogenic source. Benzeneand toluene are absent but two xylene isomers are pres-ent. Thus, a nondiffusional (lateral) migrational processcould be responsible, as suggested for Sample 603B-34-2,134 cm.

CONCLUSIONS

1. Organic-carbon-lean sections generally contain on-ly C1-C3 hydrocarbons that are believed to have migratedthroughout the hole from organic-carbon-rich sections.In richer sections, these compounds show sporadicallyhigher values, particularly in shallower parts of the hole.The increased "smearing out" of the profiles with depthsuggests that diffusion over geological time smooths outspikes, which are initially caused by early biogenic pro-duction near the sediment/water interface.

2. No evidence was found for vertical diffusional mi-gration of C4-C8 hydrocarbons, even over a few cm, inany section of the hole.

3. Sporadic and simple distributions of C4-C6 com-pounds in organic-carbon-rich, shallow sections suggestin situ generation by biological (or low-temperature chem-ical) processes occurring near the sediment/water inter-face shortly after deposition as commonly found for sur-face sediments (Whelan and Hunt, 1984).

4. The concentrations and complexity of the C4-C8hydrocarbon mixture increased in two deeper sections(603B-34-2, 134 cm and 603B-81-3, 120 cm), suggestinga switch either to thermal generation over a very narrowdepth range (for which there is no sedimentological evi-dence) or to the influence of a nondiffusional (lateral)petroleum migration process, possibly similar to thatfound in immature surface sediments of the geothermal-ly hot Guaymas Basin area. The relatively high propor-tions of xylene and ethyl benzene found in these twointervals are consistent both with a higher temperaturesource and/or with lateral petroleum migration.

ACKNOWLEDGMENTS

We would like to thank Dr. Ken Peters and Dr. Keith Thompsonfor their careful reading of the manuscript. This work was supportedby Department of Energy Contract No. EG-77-02-4392. Woods HoleOceanographic Institution Contribution No. 6051.

REFERENCES

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

Jasper, J. P., Whelan, J. K., and Hunt, J. M., 1984. Migration of Clto C8 volatile organic compounds in sediments from the Deep SeaDrilling Project, Leg 75, Hole 53OA. In Hay, W. W., Sibuet, J. C ,et al., Init. Repts. DSDP, 75, Pt. 2: Washington (U.S. Govt. Print-ing Office), 1001-1008.

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J. K. WHELAN, C. BURTON

Oremland, R. S., 1981. Microbial formation of ethane in anoxic estu-arine sediments. Appl. Environ. Microbiol., 42:122-129.

Rice, D. D., and Claypool, G. E., 1981. Generation, accumulationand resource potential of biogenic gas. Am. Assoc. Pet. Geol. Bull.,65:5-25.

Sahores, J. J., and Witherspoon, P. A., 1970. Diffusion of light hy-drocarbons in water from 2°C to 80°C. In Hobson, G. D., andSpeers, G. C. (Eds.), Advances of Organic Geochemistry: New York(Pergamon Press), pp. 219-230.

Thompson, K. F. M., 1979. Light hydrocarbons in subsurface sedi-ments. Geochim. Cosmochim. Ada, 43:657.

Whelan, J. K., 1984. Volatile C1-C8 compounds in marine sediments.In Odham, G., Larsson, L., and Mardh, P. (Eds.), Gas Chroma-tography/Mass Spectrometry Applications in Microbiology: NewYork (Plenum Press),

Whelan, J. K., and Hunt, J. M., 1982. C r C 8 hydrocarbons in Leg 64sediments, Gulf of California. In Curray, J. R., Moore, D. G., etal., Init. Repts. DSDP, 64, Pt. 2: Washington (U.S. Govt. PrintingOffice), 763-779.

, 1983. Volatile C1-C8 organic compounds in sediments fromthe Peru upwelling region. Org. Geochem., 5:13-28.

Whelan, J. K., Hunt, J. M., Jasper, J., and Hue, A., 1985. Migrationof C1-C8 hydrocarbons in marine sediments. Org. Geochem., 6:683-694.

Date of Initial Receipt: 29 March 1985Date of Acceptance: 21 October 1985

1236