Rock eval analysis of organic matter in sediment core 159-959D

The Cretaceous Equatorial Atlantic Gateway between the Central and South Atlantic basins is of interest not only for paleoceanographic and paleoclimatic studies, but also because it provided particularly favourable conditions for the accumulation and preservation of organic-rich sediments. Deposition of carbonaceous sediments along the Côte d'Ivoire-Ghana Transform Margin (Ocean Drilling Program Leg 159) was intimately linked to the plate tectonic and paleoceanographic evolution of this gateway. Notably, the formation of a marginal basement ridge on the southeastern border of the transform margin provided an efficient shelter of the landward Deep Ivorian Basin against erosive and potentially oxidizing currents. Different subsidence histories across the transform margin were responsible for the development of distinct depositional settings on the crest and on both sides of the basement ridge. Whereas the southern, oceanward flank of the basement ridge was characterized by rapid, continuous deepening since last Albian-early Cenomanian, marine sedimentation on the northern, landward flank was interrupted by a period of uplift and erosion in the late Albian, and rapid subsidence started after the early Coniacian. […]

白垩纪中-南大西洋盆地的赤道大西洋通道，不仅因其对古海洋学和古气候学研究的价值而备受关注，而且由于其提供了有利于富含有机质沉积物积累和保存的特别优越条件。在科特迪瓦-加纳转换边缘（海洋钻探计划第159航次）沿线的碳质沉积物沉积，与该通道的板块构造和古海洋学演化密切相关。值得注意的是，在转换边缘东南边缘形成的边缘基底脊，为内陆深科特迪瓦盆地的侵蚀和潜在氧化流提供了有效的庇护。转换边缘不同的沉降历史，导致了基底脊顶部及其两侧形成不同的沉积环境。而基底脊南部的海洋侧翼自上一次阿尔比阶-早坎潘阶以来经历了快速而持续的加深，而基底脊北部的陆侧翼在晚阿尔比阶时期经历了抬升和侵蚀的间歇，在康尼亚克阶早期之后开始了快速沉降。