Organic Petrography and Extractable Hydrocarbons of Sediments from the Gulf of California, Deep Sea Drilling Project Leg 64

Abstract

We determined the quantity, type, and maturity of organic matter in Pleistocene sediment from the Gulf of California. We analyzed extractable hydrocarbons by capillary column chromatography and combined gas chromatography/mass spectrometry (GC/MS). We investigated kerogens by Rock-Eval pyrolysis and microscopy. Organic carbon is mostly between 1 and 2°7o in samples from the mouth of the Gulf (Holes 474 and 474A) and in the Guaymas Basin (Holes 478, 481, and 481 A) and between 2 and 4% at the Guaymas Basin slope (Hole 479). We determined total extracts of about 10 mg/g C org for all samples. The organic matter seems to be mostly terrigenous in Holes 474,474A, 478,481, and 481 A, as indicated by the extractable hydrocarbons and the macefal analysis. But we believe that the large amounts of steroid and triterpenoid hydrocarbons in some samples indicate marine and bacterial biomass, which probably is finely disseminated and cannot readily be identified under the microscope. Rederived, inert organic matter is common in these holes. In Hole 479, the terrigenous contribution is less pronounced, and algal liptinites exceed terrigenous liptinites. But in all samples, perylene is the predominant aromatic hydrocarbon. Optical and chemical investigations show that the organic matter in the Gulf of California sediment is immature, despite the high heat flow and local basaltic intrusions. We could not establish a regular maturity trend with increasing depth.

Biosphere frontiers of subsurface life in the sedimented hydrothermal system of Guaymas Basin

“…Hydrothermal pyrolysis transforms and mobilizes a major proportion of subsurface carbon sources: the organic carbon content of approx. 3–4 wt% in surficial Guaymas Basin sediments (De la Lanza-Espino and Soto, 1999) is reduced to 1–2% in subsurface sediments below sills (Rullkötter et al, 1982; Simoneit and Bode, 1982). Hydrothermal alteration of buried sedimentary organic matter generates petroleum compounds including complex mixtures of linear, branched and cycloalkanes, hopanes, steranes, diasteranes, olefins, and polynuclear aromatic hydrocarbons (PAHs; Simoneit and Lonsdale, 1982; Kawka and Simoneit, 1987; Didyk and Simoneit, 1989), low-molecular weight alkanes (Bazylinski et al, 1988), organic acids (Martens, 1990), and ammonia (Von Damm et al, 1985).…”

Weathering and biodegradation of hydrothermal petroleum in the north rift of Guaymas Basin, Gulf of California

“…The lipids of the Pleistocene sediments drilled in Hole 481 had hydrocarbon distributions analogous to those described above, supporting the dual natural sources of marine productivity and terrigenous influx (Galimov et al, 1982;Rullkötter et al, 1982;Simoneit and Philp, 1982;Thomson et al, 1982). The sedimentology was assessed as typical diatomaceous ooze with mud turbidites (Curray et al, 1982).…”

“…The source of the organic matter was primarily from marine input based on its δ 13 C values (Galimov et al, 1982;Jenden et al, 1982). However, the contemporary lipids were dominated by terrigenous input superimposed on the autochthonous marine components (Rullkötter et al, 1982;Simoneit and Philp, 1982).…”

Quantity, Provenance, and Thermal Maturity of Organic Matter from the New Jersey Continental Margin, Deep Sea Drilling Project Leg 95

“…7B; Appendix) could not be identified with confidence, although the mass spectra (Fig. 7B) resemble those of the C 2 s ster-5,24-or ster-5,24(28)-dienes found in deepsea sediments of the Gulf of California (Rullkötter et al, 1982).…”