Comparative Compositional Studies of Organic Matter in Various Deep-Sea Drilling Project Cores: ABSTRACT

Abstract

The Deep-Sea Drilling Project (JOIDES) is providing cored samples taken through the sedimentary layers of the deep ocean basins and continental rises. Preliminary organic geochemical studies on spot samples from cores in the Atlantic and Pacific Oceans have yielded data which suggest that planktonic versus terrigenous components in the total extractable organic matter may be distinguished. The biologic markers of terrestrial detritus used in this study are the high-weight paraffins (odd numbered n-C27-n-C33) with the corresponding high-weight fatty acids (even numbered n-C22-n-C30) and triterpenes. Some specific terrigenous markers found are a series of dehydroabietic acids, traceable to a conifer rosin derivation. In addition, a remarkable degree of preservation of certain suites of organic compounds, such as monolefins and diolefins (phytadienes), has been found in anoxic recent marine cores, decreasing markedly with depth, for example, in a continuous calcareous clay and organic carbon-rich sediment from the Cariaco Trench. A concentration correlation of the phytadienes with the chlorine pigments is positive, indicating the source of these olefins is phytoplankton chlorophyll metabolized by zoo-plankton and thus preserved. Recently available continuous cores from the Cariaco Trench and the Bengal fan promise to yield an excellent opportunity to analyze further and then compare planktonic, calcareous clay-rich anoxic sediments with oxic sandy-silt sequences having a high terrigenous component. End_of_Article - Last_Page 772------------