Morphology and Stratigraphy of Continental Margins During Tertiary Global Change: From Carbonate Ramps to Clastic Progradation

9521336新生代Steckler许多边缘经历了重大的形态变化，从碳酸盐斜坡演化到前进型碎屑陆架，而世界气候从温室条件永久地转变为冰库条件。在新泽西州边缘，从碳酸盐斜坡向硅屑陆棚的转换发生在渐新世早期。在安哥拉边缘，始新世-渐新世界线时间证明了一次重大的侵蚀事件。我的中新世，两个边缘都以硅质碎屑进积为主，边缘演化为现代大陆边缘，具有平坦的陆架和陆架斜坡断裂。在其他边缘也观察到了这种模式，需要从渐新世到中新世增加沉积物供应。到渐新世中期，碳酸盐工厂在以前占主导地位的碳酸盐斜坡上关闭了。硅质碎屑的转变与冰库条件的发展、海平面的长期下降以及由于大陆季节性增强和侵蚀而增加的陆源沉积物供应同时发生。这项研究将重建非洲边缘，以了解从地震数据中大陆边缘形态和地层的变化。将对边缘进行反剥离或正演模拟，以确定近似的构造沉降。***

9521336 Steckler In the Cenozoic many margins underwent major changes in morphology and evolved from carbonate ramp to prograding clastic shelves, while the world climate changed permanently from a hothouse to icehouse conditions. On NJ margin the switch from carbonate ramp to siliciclastic shelf occurred in the early Oligocene. On the Angola margin the Eocene-Oligocene boundary time evidenced a major erosional event. My Miocene both margins were dominated by siliciclastic progradation and margins evolved to the modern continental margins with flat shelves and shelf- slope breaks. This pattern is also observed at other margins and require an increase in sediment supply from Oligocene to Miocene. By mid-Oligocene the carbonate factory had shut down over the previously dominant carbonate ramps. The siliciclastic shift occurs at the same time as the development of the icehouse conditions, a long-term lowering of sea level and increase in terrigenous sediment supply due to enhanced continental seasonality and erosion. The study will reconstruct the African margin to understand the shift in continental margin morphology and stratigraphy from seismic data. Backstripping or forward modeling of the margin will be performed to determine the approximate tectonic subsidence. ***