Sedimentary budget of the Southwest Sub‐basin, South China Sea: Controlling factors and geological implications

Abstract

Calculation of the sediment budget in the South China Sea abyssal basin lacks constraints from drilling data and reinterpretation of seismic data. On the basis of six multichannel seismic profiles across the Southwest Sub-basin (SWSB) and the drilling data from International Ocean Discovery Program Expedition 349, we divided the Cenozoic sediments into four sedimentary units. The sedimentary budget of the abyssal basin at different geological times was calculated. The previous works in the Mekong continental shelf and slope areas were integrated to calculate the sediment budget of the whole SWSB. Our researches show that the sediment budget in the SWSB increased during the Palaeogene and reached its first peak because of intensified erosion, which might have resulted from the continued uplift of the Tibetan Plateau and accelerated southeastward extrusion of the Indo-China Peninsula. Since the Late Miocene, the sediment budget was mainly influenced by the East Asia monsoon, that is, the intensified winter monsoon decreased the sediment budget of the entire area during the Late Miocene, whereas the strengthened summer monsoon increased the sediment budget during the Pliocene and reached a peak during the Pleistocene. The sediment budgets of the Mekong continental shelf, the Mekong continental slope, and the abyssal basin have distinct characteristics, relating to the infilling sequence of the terrestrial sediments in different regions. The sediment provenance of the SWSB was mainly from the Indo-China Peninsula, the Nansha area, and the Palawan before the Late Miocene. After that time, sediments were mainly transported from the modern Mekong River.

Himalayan‐Tibetan Erosion Is Not the Cause of Neogene Global Cooling

“…Geochemical data obtained the Mekong are as studied by Liu, Clift, Murray, et al (2017), Pearl from Wan et al (2007), and Indus from Zhou et al (2021). Sediment flux data for the Indus and Pearl rivers are from Clift (2006), with flux data for the Mekong from Wu et al (2018).…”

“…The scatter of CIA values prior to 8 Ma (Figure 2f) are interpreted to represent a mixed sediment provenance, for which we now correct. Although sediment budgets only based on proximal Vietnamese shelf records indicate increasing sediment delivery rates after ∼8 Ma (Li et al., 2013), a revised budget accounting for sedimentation on the deep oceanic crust adjacent to the margin indicates a relatively steady sediment flux since ∼16 Ma (Wu et al., 2018) (Figure 2c).…”

Sedimentary budget of the Northwest Sub-basin, South China Sea: controlling factors and geological implications

“…With these drilling results and multichannel seismic (MCS) data, well dated abyssal stratigraphy and the lithologies of different sedimentary units are now possible. The sedimentary budget of the Southwest Sub-basin has been constrained using this approach (Ding et al 2016;Wu et al 2018). Results show that the uplift of Tibetan Plateau, the accelerated southeastward extrusion of the Indochina Peninsula, and the East Asia monsoon dominated control of the sedimentary budget.…”

“…In this study, we integrated the drilling results and downhole geophysical logging from IODP Expeditions 367 and 368, with MCS data to conduct a detailed seismic stratigraphy study of the Northwest Sub-basin (NWSB), and then calculated the sedimentary budget through time, in doing so we reconstructed the sedimentary history of the NWSB. To better understand the significance of sediment volumes deposited in the NWSB, we compared our results with the sedimentary budget of continental margin basins, such as the Pearl River Mouth Basin, the Yinggehai-Song Hong Basin, and the Qiongdongnan Basin (Clift 2006;Clift and Sun 2006), as well as the Southwest Sub-basin (Wu et al 2018). The objective of the sedimentary budget studies is to determine the flux and transport paths of terrestrial sediments, and to identify the major controlling factors over the sedimentary budget in order to increase understanding of the interaction between solid earth tectonic activity, climate change, and sedimentary evolution of the NWSB, SCS.…”

“…Sedimentary budgets for the major marginal and abyssal basins in the South China Sea. (a) Yinggehai-Song Hong Basin(Clift and Sun 2006), (b) Qiongdongnan Basin(Clift and Sun 2006), (c) Pearl River Mouth Basin(Clift 2006), (d) Baiyun Sag(Xie et al 2013), (e) Southwest Sub-basin(Wu et al 2018), and (f) Northwest Sub-basin.…”