Stable Isotopes of Oxygen and Carbon in Carbonates and Organic Material from Pleistocene to Upper Miocene Sediments at Site 374 (DSDP Leg 42A)

Hahn-Weinheimer, Paula; Fabricius, F.; Müller, Jens Daniel; Sigl, W.

doi:10.2973/dsdp.proc.42-1.115.1978

Cited by 2 publications

(2 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The type of organic matter in Mediterranean sapropels is still a matter of debate. Some authors favor a predominantly terrigenous (Deroo et al, 1978;Sigl et al, 1978;Hahn-Weinheimer et al, 1978) or marine (e.g., Nesteroff, 1973;Cita and Grignani, 1982) origin of the organic matter. A dominance of amorphous organic matter and high concentrations of C 1 to C 12 compounds were taken as evidence to support the latter view.…”

Section: Organic Geochemical Studiesmentioning

confidence: 99%

Biological marker significance of organic matter origin and transformation in sapropels from the Pisano Plateau, Site 964

Rullkötter¹,

Rinna²,

Bouloubassi³

et al. 1998

Proceedings of the Ocean Drilling Program, 160 Scientific Results

View full text Add to dashboard Cite

The organic matter in a series of 39 sapropel samples from Hole 964D drilled during Ocean Drilling Program Leg 160 in the Ionian Basin of the Eastern Mediterranean Sea has been characterized. Organic carbon contents exceed 20% in many sapropels of Pliocene to early Pleistocene age, but are conspicuously lower in those of the late Pleistocene and Holocene. The organic matter is predominantly of marine origin, with varying admixtures of terrigenous organic matter. The most abundant molecular algal markers are long-chain alkenones, alkandiols, and alkanolones (ketools) as well as a significant proportion of sterols. Terrigenous markers include long-chain alkanes, n-alcohols, and fatty acids. Although strong alteration of the organic matter by sulfate-reducing bacteria is inferred from the high total sulfur contents of the sapropels, there was little direct molecular evidence of a bacterial biomass contribution. High C org :N ratios, exceeding values of 20, particularly in the most organiccarbon-rich sapropels, have to be interpreted as the result of partial degradation of the sinking organic matter with selective remineralization of nitrogen-bearing compounds.

show abstract

Section: Organic Geochemical Studiesmentioning

confidence: 99%

Biological marker significance of organic matter origin and transformation in sapropels from the Pisano Plateau, Site 964

Rullkötter¹,

Rinna²,

Bouloubassi³

et al. 1998

Proceedings of the Ocean Drilling Program, 160 Scientific Results

View full text Add to dashboard Cite

show abstract

“…They were first called to the attention of marine researchers in the Japan Trench Transect during Leg 56, where they occur well below the carbonate compensation depth (Okada, 1980). Only a few isotopic studies have been made on authigenic carbonate phases in deep sea environments (Milliman et al, 1969;Anderson and Lawrence, 1976;Hein et al, 1979), except for evaporation phases in the Mediterranean Sea (Hahn-Weinheimer et al, 1978;McKenzie and Ricchiuto, 1978). Carbonate nodules in sedimentary rocks now exposed on land have been isotopically studied (Weber et al, 1964;Galimov et al, 1968;Fritz et al, 1971;Suss and Kolodny, 1972;Hirabayashi, 1977), and carbonate nodules in unconsolidated deep sea sediments have recently been reported by Hein et al (1979).…”

Section: Introductionmentioning

confidence: 99%

Deep Sea Carbonate Nodules from the Middle America Trench Area off Mexico, Deep Sea Drilling Project Leg 66

Wada¹,

Niitsuma²,

Nagasawa³

et al. 1982

Initial Reports of the Deep Sea Drilling Project

View full text Add to dashboard Cite

We collected 20 carbonate nodules from the inner trench slope deposits of the Middle America Trench area off Mexico. Carbonate nodules are found only within the methane-rich layer beneath the mixed layer of methane and hydrogen sulfide. They have been investigated by microscopic, scanning electron microscopic (SEM), X-ray diffraction, and stable isotopic analytical methods. Calcite, magnesian calcite, dolomite, and rhodochrosite were recognized as carbonate minerals. Each carbonate nodule is usually represented by single species of carbonate minerals. Carbonate nodules are subdivided into micrite nodules and recrystallized nodules according to textural features. The carbonate crystallites in each micrite nodule are equidimensional. Their sizes range from several to 30 µm, as revealed by SEM micrographs.The chemical composition of calcite is changed from pure calcite to high magnesian calcite, as shown by the shift of the (104) reflection in X-ray diffraction patterns. Fe substitution for Ca in dolomite was also observed.Carbon isotopic composition shows an unusually wide range-from -42.9 to + 13.5% O -in PDB scale, whereas oxygen isotopic compositions of almost all the carbonate nodules are constantly enriched in 18 O from + 3.4 to + 7.60% 0 in PDB scale. These wide variations in carbon isotopic composition indicate several sources for the carbon in carbonate nodules. Carbon with a negative δ 13 C value was derived from biochemical oxidation of methane with a negative δ 13 C value. On the other hand, carbon with positive δ 13 C value was probably formed during methane production in an anoxic condition.

show abstract

Stable Isotopes of Oxygen and Carbon in Carbonates and Organic Material from Pleistocene to Upper Miocene Sediments at Site 374 (DSDP Leg 42A)

Cited by 2 publications

References 10 publications

Biological marker significance of organic matter origin and transformation in sapropels from the Pisano Plateau, Site 964

Biological marker significance of organic matter origin and transformation in sapropels from the Pisano Plateau, Site 964

Deep Sea Carbonate Nodules from the Middle America Trench Area off Mexico, Deep Sea Drilling Project Leg 66

Contact Info

Product

Resources

About