Accumulation of organic and inorganic carbon in Pliocene-Pleistocene sediments along the SW African margin

Author(s): Giraudeau, Jacques; Meyers, Philip A.; Christensen, Beth A.
Author Affiliation(s): Primary:
Université Bordeaux I, CNRS, Talence, France
Other:
Universite Bordeaux I, France
University of Michigan, United States
Furman University, United States
Volume Title: Neogene and Quaternary evolution of the Benguela coastal upwelling system
Volume Author(s): Christensen, Beth A., editor; Giraudeau, Jacques
Source: Marine Geology, 180(1-4), p.49-69; Evolution of major upwelling systems , American Geophysical Union 1999 fall meeting, San Francisco, CA, Dec. 13-17, 1999, edited by Beth A. Christensen and Jacques Giraudeau. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 52 refs.; illus., incl. 2 tables, sketch maps
Summary: The Ocean Drilling Program Leg 175 recovered a unique series of stratigraphically continuous sedimentary sections along the SW African margin, an area which is presently affected by active coastal upwelling. The accumulation rates of organic and inorganic carbon are a major component of this record. Four Leg 175 sites (1082, 1084, 1085, 1087) are chosen as part of a latitudinal transect from the present northern to southern boundaries of the Benguela Current upwelling system, to decipher the Pliocene-Pleistocene history of biogenic production and its relationship with global and local changes in oceanic circulation and climate. The pattern of CaCO3 and Corg mass accumulation rates (MARs) over 0.25-Myr intervals indicates that the evolution of carbon burial is highly variable between the northern and the southern Benguela regions, as well as between sites that have similar hydrological conditions. This, as well as the presence over most locations of high-amplitude, rapid changes of carbon burial, reflect the partitioning of biogenic production and patterns of sedimentation into local compartments over the Benguela margin. The combined mapping of CaCO3 and Corg MARs at the study locations suggests four distinct evolutionary periods, which are essentially linked with major steps in global climate change: the early Pliocene, the mid-Pliocene warm event, a late Pliocene intensification of northern hemisphere glaciation and the Pleistocene. The early Pliocene spatially heterogeneous patterns of carbon burial are thought to reflect the occurrence of mass-gravitational movements over the Benguela slope which resulted in disruption of the recorded biogenic production. This was followed (3.5-3 Ma) by an episode of peak carbonate accumulation over the whole margin and, subsequently, by the onset of Benguela provincialism into a northern and a southern sedimentary regime near 2 Ma. This mid and late Pliocene evolution is interpreted as a direct response to changes in the ventilation of bottom and intermediate waters, as well as to dynamics of the subtropical gyral circulation and associated wind stress. Abstract Copyright (2002) Elsevier, B.V.
Year of Publication: 2002
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Africa; Algae; Atlantic Ocean; Benguela Current; Biochemical sedimentation; Bioclastic sedimentation; Biogenic processes; Burial diagenesis; Calcium carbonate; Carbon; Carbonate sediments; Cenozoic; Climate change; Continental margin sedimentation; Diagenesis; Glacial environment; Glaciomarine environment; Inorganic materials; Leg 175; Marine environment; Marine sediments; Microfossils; Nannofossils; Neogene; ODP Site 1082; ODP Site 1084; ODP Site 1085; ODP Site 1087; Ocean Drilling Program; Organic carbon; Paleo-oceanography; Paleocirculation; Paleoclimatology; Paleocurrents; Paleoecology; Plantae; Pleistocene; Pliocene; Quaternary; Sedimentation; Sedimentation rates; Sediments; South Atlantic; Southeast Atlantic; Southern Africa; Tertiary; Upwelling
Coordinates: S210539 S210539 E0114914 E0114914
S253049 S253049 E0130140 E0130140
S292228 S292228 E0135924 E0135924
S312754 S312754 E0151839 E0151839
Record ID: 2002026683
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands