Large-scale erosional response of SE Asia to monsoon evolution reconstructed from sedimentary records of the Song Hong-Yinggehai and Qiongdongnan basins, South China Sea
Long Van Hoang, Peter D. Clift, Anne M. Schwab, Mads Huuse, Duc Anh Nguyen, Sun Zhen, 2010. "Large-scale erosional response of SE Asia to monsoon evolution reconstructed from sedimentary records of the Song Hong-Yinggehai and Qiongdongnan basins, South China Sea", Monsoon Evolution and Tectonic–Climate Linkage in Asia, P. D. Clift, R. Tada, H. Zheng
Download citation file:
The Song Hong-Yinggehai (SH-Y) and Qiongdongnan (Qi) basins together form one of the largest Cenozoic sedimentary basins in SE Asia. Here we present new records based on the analysis of seismic data, which we compare to geochemical data derived from cores from Ocean Drilling Program (ODP) Site 1148 in order to derive proxies for continental weathering and thus constrain summer monsoon intensity.
The SH-Y Basin started opening during the Late Paleocene–Eocene. Two inversion phases are recognized to have occurred at c. 34 Ma and c. 15 Ma. The Qi Basin developed on the northern, rifted margin of South China Sea, within which a large canyon developed in a NE–SW direction.
Geochemical and mineralogical data show that chemical weathering has gradually decreased in SE Asia after c. 25 Ma, whereas physical erosion became stronger, especially after c. 12 Ma. Summer monsoon intensification drove periods of faster erosion after 3–4 Ma and from 10–15 Ma, although the initial pulse of eroded sediment at 29.5–21 Ma was probably triggered by tectonic uplift because this precedes monsoon intensification at c. 22 Ma. Clay mineralogy indicates more physical erosion together with high sedimentation rates after c. 12 Ma suggesting a period of strong summer monsoon in the Mid-Miocene.
Figures & Tables
The Earth’s climate varies through geological time as a result of external, orbital processes, as well as the positions of continents, growth of mountains and the opening and closure of oceanic gateways. Climate modelling suggests that the intensity of the Asian monsoon should correlate, at least in part, with the uplift history of the Tibetan Plateau and the Himalaya, as well as the evolution of gateways and the retreat of shallow seas in Central Asia. Long-term reconstructions of both mountain building and monsoon activity are key to testing the proposed links. This collection of papers presents a series of new studies documenting the variations of the Asian monsoon on orbital and tectonic timescales, together with the impact this has had on environmental conditions. The issue of which proxies are best suited to measuring monsoons is addressed, as is the effect that the monsoon has had on erosion and the formation of the stratigraphic record both on and offshore.