Climate-tectonic control on the structure and built-up of the Bengal Shelf: Processing and evaluation of high-resolution multichannel seismic profiles for an IODP-Proposal

恒河-雅鲁藏布江从喜马拉雅山向孟加拉湾输送的泥沙量是世界上最大的。这种源-汇系统是由气候-构造联系驱动的，即季风和喜马拉雅山的隆起。因此，恒河-雅鲁藏布江的沉积中心包含了气候和构造过程相互作用的记录。可以在深海扇和相应的IODP提案552（France-Lanord，Spiefounder等人）中研究该系统的长期新近纪历史。得到了积极的评价，并准备钻探。然而，该系统的短期更新世历史记录在快速积累的陆架沉积物中。与上覆的印缅板块碰撞所引起的陆架构造沉降，不断为季风降水从喜马拉雅山输送的高陆源通量提供新的容纳空间。通过使命专用平台或新的JOIDES决议在孟加拉国大陆架钻探将有助于了解：通过研究碎屑物质的来源和确定盐度变化来研究印度季风系统的更新世气候变化，通过地震地层学、确定大陆架边缘的旧石器海滩、山脊和低位沉积物的年代来研究更新世海平面的变化，该地区更新世沉降的估计，全新世季风变化，包括陆架峡谷中超高分辨率记录的热带气旋频率（~ 1公里全新世沉积物），通过分析海洋和陆地生物标志物，以及通过分析峡谷沉积物的地球化学，研究印度-喜马拉雅地区森林砍伐和农业集约化的影响。本提案旨在处理2006年索内号SO 188号巡航期间在大陆架和上斜坡记录的高分辨率多通道数据。结合SO 93/SO 126剖面资料和露头单元样品，利用地震地层学方法分析了外陆架和上斜坡的构造格架。根据这一评价，提出了在陆架峡谷、外陆架和上斜坡进行全新世和更新世IODP钻探的建议。

The Ganges-Brahmaputra rivers transport the worldwide largest sediment freight from the Himalayas to the Bay of Bengal. This source-to-sink system is driven by climatic-tectonic links, i.e. the monsoon and the uplift of the Himalayas. Consequently the sedimentary depocenters of the Ganges-Brahmaputra rivers contain a record of the interaction of climate and tectonic processes. The long-term Neogene history of the system can be studied in the deep-sea fan and the corresponding IODP proposal 552 (France-Lanord, Spieß et al.) was positively evaluated and is ready for drilling. The shortterm Pleistocene history of the system, however, is recorded in the rapidly accumulating shelf sediments. The tectonic subsidence of the shelf, caused by the collision with the overriding Indo-Burmese plate, constantly adds new accommodation space for the high terrigenous flux delivered from the Himalayas by the monsoonal precipitation. Drilling at the shelf of Bangladesh by a Mission Specific Platform or the new JOIDES Resolution will contribute to understand: The Pleistocene climatic variability of the Indian monsoon system by studying the provenance of detrital material and determining salinity changes, The Pleistocene sea level changes by seismic stratigraphy, dating of oolithic beaches ridges and low-stand deposits at the shelf edge, An estimation of the Pleistocene subsidence of the area, The Holocene monsoonal changes including the frequency of tropical cyclones with an ultra-high resolution record in the shelf canyon (~ 1 km Holocene sediments) by analysing marine and terrestrial biomarkers, and The effects of deforestation and intensification of agriculture in the Indian-Himalaya region by analysing the geochemistry of canyon sediments. This proposal aims to process the high-resolution multichannel data recorded on the shelf and upper slope during the 2006 SONNE cruise SO188. In combination with the data of SO93/SO126 profiles and the samples of outcropping units, the structural framework of the outer shelf and upper slope is analysed by using seismic stratigraphic methods. Based on this evaluation an IODP drilling proposals with sites in the shelf canyon, outer shelf and upper slope for the Holocene and Pleistocene history are developed.