Wagner, Thomas; Lohmann, G. Pat; Shin, In Chul (1996): Carbonate and organic carbon deposition to the Plio/Pleistocene eastern Equatorial Atlantic off Ivory Coast/Ghana (ODP Hole 959C). Geological Society of America (GSA), Boulder, CO, United States, In: Anonymous, Geological Society of America, 28th annual meeting, 28 (7), 121, georefid:1997-040205
Abstract:
Glacial/interglacial sedimentation in the Eastern Equatorial Atlantic is well documented to be effectively controlled by changes in paleoproductivity and variable eolian dust supply from central Africa. These cyclic paleoenvironmental changes caused typical carbonate, sand fraction, and TOC patterns showing elevated carbonate and sand contents during interglacials contrasted by high TOC contents during glacials. Opposite to typical Atlantic records 959C deposits, drilled on the upper flank of the Ivory Coast/Ghana transform margin, reveal elevated carbonate and sand contents during glacials and low contents during interglacials. The corresponding TOC profil lacks a clear glacial/interglacial variability but scatter at elevated levels. High TOC contents throughout the Plio/Pleistocene are surprising considering continuous low sedimentations rates probably related to enforced bottom current activities at the exposed position of 959C. Heavy stable carbon isotope records (delta 13C org) indicate dominant preservation of marine organic carbon (70-100%). Pyrolytic and microscopic characteristics, in contrast, favour a contrasting interpretation. Despite generally enhanced TOC values Hydrogen Indices remain below 100 mgHC/gTOC suggesting high proportions of hydrogen-depleted organic matter, such as of terrigenous plants. Organic petrographic studies clearly support pyrolytic data as detrital allochthonous organic particles contribute 40-70% of the total maceral composition. The contradiction between delta 13C org and microscopic results is likely explained by eolian-derived C4 plant debris from central Africa, Estimated amounts of C4 plants required to compensate for the observed contradiction vary from 20% to 40% of the total organic matter.
Coverage:
West: -80.0000 East: 20.0000 North: 75.0000 South: -60.0000
West: NaN East: NaN North: NaN South: NaN
West: NaN East: NaN North: NaN South: NaN
West: NaN East: NaN North: NaN South: NaN
Relations:
Data access: