The Bengal Fan stratigraphy as a function of tectonic and climate - Correlation of IODP Expedition 354 results and available seismic data from the Bay of Bengal

覆盖整个孟加拉湾的孟加拉扇是喜马拉雅山脉侵蚀历史最完整的记录。因此，扇体上的沉积作用受喜马拉雅-青藏体系的发育、区域气候的历史演变及其相互作用的控制。因此，IODP 354号考察队（孟加拉扇）致力于研究（1）喜马拉雅山和西藏地形特征的发展所产生的喜马拉雅早期侵蚀和（2）亚洲季风的新近纪历史及其对沉积物供应和通量的影响。该考察于2015年2月/3月进行，联合首席科学家是C。弗朗斯·兰诺和V·斯皮斯在第354次考察期间，在8°N的东西向样带上钻探了7个地点。这种钻探策略还允许确定通常用于海底扇的横向沉积中心迁移，并在解释钻井结果时利用这一结果。在这一更新建议的框架内，建议将IODP Expedition 354的结果与两次现场前调查的现有地震数据网相关联（RV索内号在孟加拉湾进行SO 125和SO 188巡航），从区域构造和气候演化的角度建立孟加拉扇的新地层。现有地层学的依据是：a）来自DSDP 218号现场点取心的不良年龄限制; B）仅基于SO 125号巡航期间在8°N附近收集的地震数据。包括来自Cruise SO 188的所有可用数据将把地层扩展到11°N。地层特征的新测年将提供新的，重要的见解建立的风扇作为喜马拉雅山/西藏系统和亚洲季风的历史的功能。最后，该项目将提高对控制源-2-汇系统的过程的总体理解。在项目运行阶段，所有可用的地震数据都被（重新）处理。地震地层分析已经在进行中，并将继续对已钻探的半深海层进行分析，以最终确定可靠的区域地层。以下解释的目的是准确确定孟加拉扇上河道-堤坝系统的起始点，确定各个河道-堤坝系统的时序和平均寿命，以及研究这些不同时间段内从北到南的扇体结构变化。所有这些结果将用于沉积物通量的预算，并为IODP Exp。354社区，因为单钻孔的结果必须根据该横向高动态系统进行评估

The Bengal Fan, which covers the entire Bay of Bengal, is the most complete recorder for the erosional history of the Himalayans. Consequently the sedimentation on the fan is controlled by the growth of the Himalaya/Tibetan system, the past evolution of the regional climate and their interactions. Therefore IODP Expedition 354 (Bengal Fan) is dedicated to study (1) the early stage of Himalayan erosion generated by the development of the Himalaya and Tibet as topographic features and (2) the Neogene history of the Asian monsoon and its impact on sediment supply and flux. The expedition was carried out in February/March 2015, co-chief scientists were C. France-Lanord and the V. Spiess. During Expedition 354 seven sites were drilled on a East-West transect at 8°N. This drilling strategy also allows determining the lateral depocenter migration typically for submarine fans, and utilizing this result during interpretation of drilling results.In the frame of this renewal proposal it is proposed to correlate results from IODP Expedition 354 and the available seismic data net from two pre-site surveys (RV Sonne cruises SO125 and SO188) in the Bay of Bengal to establish a new stratigraphy for the Bengal Fan with respect to the regional tectonic and climatic evolution. The existing stratigraphy bases a) on poor age constraints from the just spot-cored DSDP Site 218 and b) only on seismic data gathered during Cruise SO125 around 8°N. Including all available data from Cruise SO188 will extend the stratigraphy to 11°N. New dating of stratigraphic features will give new, significant insights into the build-up of the fan as a function of the histories of the Himalaya/Tibetan system and the Asian monsoon. Finally this project shall improve the general understanding of processes controlling soure-2-sink systems.In the running project phase all available seismic data were (re)-processed. A seismo-stratigraphic analysis is already ongoing and shall be continued with respect to the drilled dated hemipelagic layer to finally establish a robust regional stratigraphy. Objectives of the following interpretation will be the exact determination of the onset of channel-levee systems on the Bengal Fan, the identification of succession and average lifetimes of individual channel-levee systems for dated time slices, and the study of variations of fan architecture from north to south within these different time slices. All these results will be utilized in the budgeting of sediment fluxes, and are of significant relevance for the IODP Exp. 354 community, since results from single drill holes have to be assessed in the light of this lateral highly-dynamic system