Millennial- to centennial-scale record of African climate variability and organic carbon accumulation in the Coniacian-Santonian eastern tropical Atlantic (Ocean Drilling Program Site 959, off Ivory Coast and Ghana)

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doi: 10.1130/0091-7613(2003)031<0135:MTCSRO>2.0.CO;2
Author(s): Hofmann, P.; Wagner, T.; Beckmann, B.
Author Affiliation(s): Primary:
University of Cologne, Cologne, Federal Republic of Germany
University of Bremen, Federal Republic of Germany
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 31(2), p.135-138. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. 25 refs.; illus., incl. sect., sketch map
Summary: Millennial- to centennial-scale geochemical records of Coniacian to Santonian deposits from the Deep Ivorian Basin are used to develop a model for the accumulation of black shales in equatorial regions during the final of the Cretaceous oceanic anoxic events (OAE). Proxy records from Ocean Drilling Program Site 959 document a strong precessional signal in the occurrence of black shales, the abundance of quartz, and clay mineralogy during OAE 3. We hypothesize that this signal reflects changes in atmospheric circulation patterns, which in turn caused latitudinal shifts of continental climate belts across western Africa. Furthermore we propose that the periodic deposition of black shales occurred in response to adjustments of oceanic circulation in the Deep Ivorian Basin resulting from climate-controlled fluctuations in continental runoff. A new high-resolution cyclostratigraphic framework allowed us to estimate a rapid change--within <1000 yr--from dysoxic (background) to anoxic or euxinic (black shale) environmental conditions, followed by black shale deposition for ∼10 k.y. and a gradual return to the initial dysoxic conditions. Our findings imply a highly dynamic Late Cretaceous atmosphere-ocean system.
Year of Publication: 2003
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Africa; Algae; Anaerobic environment; Atlantic Ocean; Biostratigraphy; Biozones; Black shale; Carbon; Clastic rocks; Clay mineralogy; Climate change; Climate forcing; Coniacian; Cretaceous; Cycles; Cyclostratigraphy; Depositional environment; Dysaerobic environment; East Atlantic; Equatorial region; Euxinic environment; Framework silicates; Ghana; Ivory Coast; Leg 159; Marine environment; Mesozoic; Microfossils; Nannofossils; ODP Site 959; Ocean Drilling Program; Orbital forcing; Organic carbon; Paleo-oceanography; Paleoatmosphere; Paleocirculation; Paleoclimatology; Plantae; Quartz; Santonian; Secular variations; Sedimentary rocks; Sedimentation rates; Senonian; Silica minerals; Silicates; Tropical environment; Upper Cretaceous; West Africa
Coordinates: N033740 N033740 W0024408 W0024408
Record ID: 2003018497
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