晚更新世以来巽他陆架暴露对沉积物输运模式和风化沉积记录的影响

巽他陆架是热带地区最大的陆架，冰期时陆架出露改变了其原有的海陆格局和沉积环境。目前巽他陆架古环境研究的一个主要争议和关键问题是如何准确揭示陆架和海区沉积物来源及环境信号传递过程与保存机制，其核心是陆架暴露对陆源沉积物“源—汇”过程的影响。本项目提出巽他陆架在冰期和间冰期经历了“源—汇”角色转换，即在间冰期陆架是周边岛屿入海沉积物的“汇”，而冰期则转变为陆坡和深海盆地的沉积物“源”，进而影响环境信号向深海传递。本项目以“太阳号”获取的南海西南陆坡钻孔为基础，结合现代巽他陆架周边入海河流沉积物的端元特征，借助234U/238U精确厘定钻孔沉积物来源和输运过程，揭示冰期陆架暴露和沉积环境改变如何影响入海沉积物来源；并以沉积滞留时间为线索，为冰期陆架暴露风化加强的猜想寻找更充分证据。本项目将深化巽他陆架环境演化和低纬海陆相互作用研究，为我国学者倡议的巽他陆架IODP钻探计划申请提供参考和资料支撑。

The Sunda shelf is the largest shelf in tropical region and the emergence of the broad shelf during glacial period may induce significant change of sedimentary environment. One of the major debate and critical issue for palaeoenvironmental study on the Sunda shelf is how to distinguish the sediment sources and the mechanism of signal transmission, while the key is the impact of shelf emergence on sediment “Source-to-Sink” processes. In this study, we propose that the shelf has played different roles in the glacial-interglacial cycle. In interglacial, the shelf is the Sink of sediments from adjacent rivers in the islands, while it turns to be a Source for sediment deposited in the continental slope during the glacial period. Hereby, on base of sediment cores drilled by SONNE RV in the continental slop in southwest South China Sea and sediments from rivers around Sunda shelf, we aim to trace the sediment provenance using 234U/238U isotopes and reveal the impact of shelf emergence on sediment transport. Furthermore, we compare chemical weathering intensity and sediment residence time in terms of “comminution age”, in order to find more robust evidences to interpret the enhance of weathering intensity during glacial period. This study can improve our understanding of the palaeoenvironmental evolution in the Sunda shelf and also provide helpful knowledge and reference for the coming IODP proposal in Sunda shelf leading by Chinese scientific community.