Middle to Late Pleistocene Evolution of the Bengal Fan: Integrating Core and Seismic Observations for Chronostratigraphic Modeling of the IODP Expedition 354 8° North Transect
Middle to Late Pleistocene Evolution of the Bengal Fan: Integrating Core and Seismic Observations for Chronostratigraphic Modeling of the IODP Expedition 354 8° North Transect
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DOI：
10.1029/2019gc008878
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发表时间：
2020-04
期刊：
影响因子：
3.7
通讯作者：
B. Reilly;F. Bergmann;M. Weber;J. Stoner;P. Selkin;L. Meynadier;T. Schwenk;V. Spiess;C. France‐Lanord
中科院分区：
文献类型：
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作者：
B. Reilly;F. Bergmann;M. Weber;J. Stoner;P. Selkin;L. Meynadier;T. Schwenk;V. Spiess;C. France‐Lanord
基于国际大洋发现计划354孟加拉扇考察的结果和对GeoB97-020/027地震线的分析，我们使用一种新的年龄深度模拟方法研究了中更新世至上更新世下孟加拉扇的年代学和年龄不确定性，该方法考虑了岩石地层、磁性地层、生物地层、旋回地层和地震地层的约束。最初的年代地层框架是利用区域广泛的半深海沉积单元建立的，只接受尊重遗址之间河道-堤坝系统叠加的扇沉积的年龄深度模型。在此基础上，从北纬8°~320 km的二维断面上重建了区域沉积速率和岩性沉积输入信号，与更远、更模糊的区域记录相吻合。这一年代学使我们能够在海平面、气候和构造控制的背景下讨论中更新世至上更新世下孟加拉扇的沉积史。根据堆积速率变化的时间，我们假设孟加拉扇8°N的河道-堤防系统的进积和强化在很大程度上是由海平面幅度在此期间的增加推动的。然而，这种进积也可能受到更新世气候变化和喜马拉雅侵蚀速率增加的影响，促使更多的沉积物流向扇体。
We investigate chronology and age uncertainty for the middle to upper Pleistocene lower Bengal Fan using a novel age‐depth modeling approach that factors lithostratigraphic, magnetostratigraphic, biostratigraphic, cyclostratigraphic, and seismic stratigraphic constraints, based on results from the International Ocean Discovery Program Expedition 354 Bengal Fan and analysis of the GeoB97‐020/027 seismic line. The initial chronostratigraphic framework is established using regionally extensive hemipelagic sediment units, and only age‐depth models of fan deposits that respect the superposition of channel‐levee systems between sites are accepted. In doing so, we reconstruct signals of regional sediment accumulation rate and lithogenic sediment input through the perspective of a two‐dimensional ~320 km transect at 8°N that are consistent with more distal and more ambiguous regional records. This chronology allows us to discuss the depositional history of the middle to upper Pleistocene lower Bengal Fan within the context of sea level, climate, and tectonic controls. We hypothesize, based on the timing of accumulation rate changes, that progradation and intensification of the Bengal Fan's channel‐levee system at 8°N was largely driven by increases in sea level amplitude during this time. However, it is also possible this progradation was influenced by changes in Pleistocene climate and increased Himalayan erosion rates, driving greater sediment flux to the fan.