Preliminary Lipid Analyses of Two Quaternary Sediments from the Middle America Trench, Southern Mexico Transect, Deep Sea Drilling Project Leg 66

Abstract

We investigated the solvent-extractable hydrocarbons, ketones, alcohols, and carboxylic acids of two Quaternary sediments from the Middle America Trench (Sections 487-2-3 and 491-1-5). These lipids are derived from a mixed input of autochthonous and allochthonous materials, with minor contributions from thermally mature sources. Their compositions are typical of those of immature Quaternary marine sediments, and their lipid distributions show many similarities to those of Japan Trench sediments. INTRODUCTIONThe solvent-extractable lipids of two Quaternary sediments (Sections 487-2-3 and 491-1-5) from the oceanic plate and central slope of the Middle America Trench were investigated by gas chromatography and computerized gas chromatography-mass spectrometry. The sections were chosen to permit the comparison of environments on either side of the trench. This preliminary report describes the lipid compositions of these two samples and interprets them in terms of their input sources, conditions of deposition, and extent of diagenesis. We also make a brief comparison of their lipid distributions with those of Quaternary sediments from the Japan Trench. Table 1 summarizes the lithological characteristics of the samples and includes their weights. Organic carbon determinations were not made for these samples, but the values of adjacent sections are given (site chapters, this volume).

Organic Geochemistry of Cretaceous Black Shales and Adjacent Strata from the Galicia Margin, North Atlantic Ocean

“…and rocks (Brassell et al, 1982). These long-chain-length alcohols are especially dominant in the black shale in Samples 103-638B-26R-1, 14-19 cm (Hauterivian), 103-641C-2R-4, 3-6 cm (Albian), and 103-641A-6X, CC (3-6 cm) (Cenomanian).…”

Organic Geochemistry of Quaternary Sediments from Deep Sea Drilling Project Leg 72, South Atlantic Ocean

“…Land plants commonly have hydrocarbon compositions dominated by C27, C29, and C31 rt-alkanes, whereas algae contain mostly shorter-chain components in the C16 to C20 range (Simoneit, 1978). Quaternary sediments containing terrigenous hydrocarbon distributions like those at these locations have been reported at other DSDP sites, including Sites 436 and 440 in Japan Trench (Brassell et al, 1980;Rüllkotter, Conford, et al, 1980); Sites 467, 469, and 471 offshore of southern California (Rüllkotter et al, 1981;McEvoy et al, 1981;Simoneit and Mazurek, 1981); and Sites 487 and 491 in the Middle America Trench (Brassell et al, 1982). The dominant n-alkane in these examples is n-C29, but it is «-C31 in Quaternary samples from Site 362 on the Walvis Ridge (Boon et al, 1978) and Sites 442, 443, and 444 from the northern Philippine Sea .…”

Aliphatic Hydrocarbons of a Cretaceous Black Shale and Its Adjacent Green Claystone from the Southern Angola Basin, Deep Sea Drilling Project Leg 75

“…Prior to extraction, both samples were pulverized in a Tema disc mill (as in Comet et al, 1981), and other experimental procedures followed those previously used in our other DSDP investigations (Barnes et al, 1979;Brassell et al, 1980aBrassell et al, , 1980cBrassell, Gowar, Eglinton, 1980;Brassell et al, 1982) except that the extracts were not saponified. Instead the total extract was methylated (BF 3 /MeOH) prior to thin-layer chromatography (TLC) where carboxylic acid methyl esters eluted in the 'ketone' fraction (cf.…”

“…Brassell et al, 1980a). Each lipid fraction was analyzed by gas chromatography (GC) and computerized-gas chromatography-mass spectrometry (C-GC-MS) using previously described methods (Brassell et al, 1980b(Brassell et al, , 1982. Individual compounds were characterized from a combination of their GC retention times, mass spectra, and mass fragmentographic (MF) responses by reference to literature or standard mass spectra, where possible.…”