Mesozoic biostratigraphic, paleoenvironmental, and paleobiogeographic synthesis, equatorial Atlantic

Abstract

Part of the Earth Sciences CommonsThis Article is brought to you for free and open access by the Earth and Atmospheric Sciences, Department of at DigitalCommons@University of Nebraska -Lincoln. It has been accepted for inclusion in Papers in the Earth and Atmospheric Sciences by an authorized administrator of DigitalCommons@University of Nebraska -Lincoln. ABSTRACTCretaceous sediments from Ocean Drilling Program Leg 159 on the Côte d'Ivoire-Ghana Marginal Ridge (CIGMR), eastern equatorial Atlantic, are characterized by distinct stratigraphic changes in sedimentary facies associated with changes in the composition of the clayey and organic fractions, as well as of the calcareous nannofossil, radiolarian, foraminiferal, and palynomorph assemblages. In the absence of reliable magnetostratigraphic information, an integrated biostratigraphy provides the only means used to calibrate the geologic history of the Leg 159 area.The existence of marine depositional environments as early as the late Aptian to early Albian close to the Leg 159 drill sites puts constraints on the timing of the opening of the equatorial Atlantic gateway. Marine sedimentation on the ridge suggests that the West African and South American cratons were largely detached at this segment of the margin by the middle to late Albian. During the Cenomanian to Coniacian the ridge appears to have remained in an elevated position with concurrent low deposition or condensation (Site 959), high carbonate debris accumulation (Site 960), and even erosion (Site 962). Total organic Carbon measurements and microfaunal data lead us to suggest that, following the early opening of the seaway during the Albian, circulation remained restricted in the fragmented sub-basins of the CIGMR. It probably was not until the Santonian that a deep-water connection and circulation system became established between the Central and the South Atlantic. The sedimentary and faunal record at Site 959 show that a rapid subsidence occurred during the Santonian, with sub-calcite compensation depth conditions maintained until and beyond the Cretaceous/Tertiary boundary.

Paleotemperature and paleosalinity inferences and chemostratigraphy across the Aptian/Albian boundary in the subtropical North Atlantic

“…Rifting between South America and Africa during the Early Cretaceous created initially discontinuous marine basins with thick accumulations of siliciclastic sediments and evaporites [ Natland , 1978; Rabinowitz and LaBrecque , 1979; Tucholke and Vogt , 1979; Jones et al , 1995]. As rifting continued the basins widened, deepened and became permanently interconnected with the North Atlantic between the late Aptian and early Albian [ Moullade et al , 1998; Pletsch et al , 2001; Moulin et al , 2010]. Regional hiatuses in the Albian of the North Atlantic [ Pletsch et al , 2001], including the Aptian/Albian boundary unconformity at Blake Nose, may provide evidence of episodic outflow from this incipient ocean basin.…”

Significance of ODP results on deepwater hydrocarbon exploration – Eastern equatorial Atlantic region

“…The margin itself is a transform margin associated with lateral movements along the Romanche Fracture Zone. Available data suggest that West Africa and South America were largely detached along this portion of the African margin by the middle to late Albian (Moullade et al, 1998).…”

Did the Benue Trough connect the Gulf of Guinea with the Tethys Ocean in the Cenomanian? New evidence from the palynostratigraphy of the Yola Sub-basin

“…The angiosperm pollen taxon Triorites africaensis was reported from the upper Cenomanian of the Maranhão Basin (Herngreen and Duenas Jimenez, 1990), from the upper Cenomanian of the Angola Basin (Morgan, 1978), from the lower to upper Cenomanian of the equatorial Atlantic (Moullade et al, 1998), and upper Cenomanian deposits of the Ivory Coast (Jardine, 1967). Salard-Chebolddaeff (1990) A second important species of this zone is Galeacornea causea, considered one of the key pollen taxa of the upper Albian-Cenomanian interval of the African -South American province (Hochuli, 1981).…”