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史最完整的记录者。因此，扇上的沉积受喜马拉雅/西藏体系的生长、区域气候的过去演化及其相互作用的控制。因此，IODP 354远征队（孟加拉扇）致力于研究：(1)喜马拉雅和西藏发展所产生的喜马拉雅早期侵蚀的地形特征；(2)新近纪亚洲季风的历史及其对沉积物供应和通量的影响。这次考察于2015年2月/ 3月进行，联合首席科学家是C. France-Lanord和V. Spiess。在远征354期间，在8°N的东西样带上钻了7个点。这种钻井策略还可以确定海底扇的侧向沉积中心迁移，并在解释钻井结果时利用该结果。在这一更新建议的框架内，建议将IODP 354考察队的结果与孟加拉湾两次现场前调查（RV Sonne cruises SO125和SO188）的可用地震数据网相关联，以建立一个关于区域构造和气候演化的新的孟加拉扇地层学。现有地层学的基础是：a) DSDP 218站点的点核年龄限制很差；b)仅基于SO125巡航期间在8°N附近收集的地震数据。包括Cruise SO188的所有可用数据，将地层扩展到11°N。新的地层特征定年将为扇的形成提供新的、重要的见解，作为喜马拉雅/西藏系统和亚洲季风历史的功能。最后，本项目将提高对源-2-汇系统控制过程的一般理解。在项目运行阶段，所有可用的地震数据都进行了（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地层进行分析，以最终建立一个可靠的区域地层学。以下解释的目标将是精确确定孟加拉扇上河道堤防系统的开始，确定确定时间片的单个河道堤防系统的演替和平均寿命，以及研究这些不同时间片内从北到南的扇结构变化。所有这些结果都将用于估算沉积物通量，并且对IODP Exp. 354群落具有重要意义，因为必须根据这种横向高动力系统来评估单个钻孔的结果

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