Reconstructing the Cenozoic sedimentary history of the Bay of Bengal (BoB) is significant for understanding the evolutionary history of South Asian river systems and the links between river development, tectonic deformation and global climate change. Here, we present the first long-term clay mineral record combined with Sr-Nd isotopic compositions from a 200-m-long sediment core from Ocean Drilling Program (ODP) Site 758 in the southern BoB to establish past variations in sediment sources and river evolution that have occurred since the late Eocene. Provenance analysis suggests that the contribution of the Himalayan source materials from the Irrawaddy and Brahmaputra Rivers to the study site became more important and stable since 22 Ma and 8 Ma, respectively. This new evidence indicates that the Brahmaputra and Irrawaddy Rivers were possibly initiated in the early Miocene (~22 Ma). Considering the timing of major tectonic and climatic evolution in South Asia, we conclude that the two phases of tectonic uplift of the Himalayan orogen that occurred in the early and late Miocene were the primary controls on river development in South Asia and provenance changes in the southern BoB. Global cooling and Indian drying after the late Miocene could also have strengthened Himalayan erosion and contributed more illite and chlorite to the South Asian margin.

重建孟加拉湾（BoB）的新生代沉积历史对于了解南亚河流系统的演化历史以及河流发展，构造变形和全球气候变化之间的联系具有重要意义。在这里，我们提出了第一个长期粘土矿物记录，结合了BoB南部海洋钻探计划（ODP）758号站点200米长沉积岩心中的Sr-Nd同位素组成，以建立沉积物来源和河流的过去变化自始新世以来发生的演化。来源分析表明，自伊洛瓦底江和雅鲁藏布江的喜马拉雅源物质对研究地点的贡献分别自22 Ma和8 Ma以来变得更加重要和稳定。这一新证据表明，雅鲁藏布江和伊洛瓦底江可能是在中新世早期（约22 Ma）开始的。考虑到南亚主要的构造和气候演化的时间，我们得出结论，中新世早期和晚期发生的喜马拉雅造山带的构造隆升的两个阶段是控制南亚河流发展和南部源区变化的主要控制因素。 BoB。中新世晚期后的全球降温和印度干旱也可能加剧了喜马拉雅山的侵蚀，并为南亚边缘贡献了更多的伊利石和绿泥石。我们得出的结论是，在中新世早期和晚期发生的喜马拉雅造山带的构造隆升的两个阶段是南亚河流发育和南部BoB物源变化的主要控制因素。中新世晚期后的全球降温和印度干旱也可能加剧了喜马拉雅山的侵蚀，并为南亚边缘贡献了更多的伊利石和绿泥石。我们得出的结论是，在中新世早期和晚期发生的喜马拉雅造山带的构造隆升的两个阶段是南亚河流发育和南部BoB物源变化的主要控制因素。中新世晚期后的全球降温和印度干旱也可能加剧了喜马拉雅山的侵蚀，并为南亚边缘贡献了更多的伊利石和绿泥石。