Cenozoic climate-tectonic interactions preserved in the Song Hong-Yinggehai and Qiongdongnan Sedimentary Basins, South China Sea

In this thesis, I present new results based on 2D multi-channel seismic data of the Song Hong-Yinggehai and Qiongdongnan Basins, geochemical data derived from ODP Site 1148, and sediment provenance analysis of modern sediment and Cenozoic sedimentary rocks collected along the Red River system. The Song Hong-Yinggehai Basin started opening after ~50 Ma but strong subsidence, triggered by motion on the Red River Fault, only occurred after ~34 Ma. This process was followed by thermal subsidence after ~21 Ma. In contrast, the formation the Qiongdongnan Basin is believed to be related to the development of the northern rifted margin of the South China Sea. Sediment budget estimates, coupled with geochemical data show that chemical weathering gradually decreased after ~25 Ma, while physical erosion became stronger. These data also suggest a period of the monsoon enhancement (~15-10 Ma), although with a likely initial East Asia monsoon strengthening ~23 Ma. U-Pb zircon dating coupled with Hf isotopes, muscovite Ar-Ar dating, bulk sediment Nd isotope and heavy mineral analysis allow me to draw the following points: (1) if the headwaters of the modern Yangtze, Mekong and Salween Rivers were ever connected to the palaeo-Red River then they were disconnected from the Red River no later than the Middle Miocene; (2) The palaeo-Red River flowed northeast of the Day Nui Con Voi during the Miocene and did not flow via Lao Cai and southwest of the range as it is observed today; (3) the Yangtze Craton and the Songpan Garze Block are the most important source regions to the Red River; (4) apart from the main Red River trunk, the Lo River is the most important sediment contributor to the Red River system, while the Da River is only a minor contributor.EThOS - Electronic Theses Online ServiceGBUnited Kingdo