Sedimentary evolution in the northern South China Sea since Oligocene and its responses to tectonics

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http://minmag.geoscienceworld.org/content/76/6/1401.full.pdf+html
Author(s): Li Anchun; Jie Huang; Jiang Hengyi; Wan Shiming
Author Affiliation(s): Primary:
Chinese Academy of Sciences, Institute of Oceanology, Laboratory of Marine Geology and Environment, Qingdao, China
Volume Title: Goldschmidt 2012 abstract volume
Source: Mineralogical Magazine, 76(6); Goldschmidt 2012, Montreal, QC, Canada, June 24-29, 2012. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X CODEN: MNLMBB
Note: In English. 1 refs.
Summary: The South China Sea (SCS), one of the largest marginal sea of the West Pacific, has complex geological structure, unique development mode and has been controlled by the Eurasian plate, Pacific plate and Australia - the Indian plate interaction since the late Mesozoic. Its formation underwent continental rifting, separation and seafloor spreading. The tectonic evolution has a close relationship with peripheral geological units and can be recorded by sedimentary strata. This work is try to reconstruct sedimentary evolution of the SCS and its response to tectonics since Oligocene based on a multi-proxies including a monomineralic quartz oxygen isotope (δ18O), grain-size of isolated terrigenous materials, terrigenous mineral accumulation rate of sediment samples from Ocean Drilling Program (ODP) Site 1148 in the northern SCS. The results show that the sedimentary evolution of the northern SCS Basin could be divided into five stages: period of initial expansion (34-28.5), period of intense tectonic activity (28.5-23), period of reduced tectonic activity (23-16.5), period of thermal subsidence (16.5-3.5) and period of Taiwan uplift (3.5 Ma to present). Terrigenous mineral composition and oxygen isotope values of quartz altered significantly between 28.5 Ma and 23 Ma during which provenance transition took place, corresponding to the most active period of the SCS since Oligocene. Sediments of the study area were mainly from southern source (presumptively from Palawan) during the early spreading period of the SCS. With the extensive spreading of the SCS, especially when the spreading axis of the SCS jumped to south during 25-23 Ma, Palawan continental block moved away from the study site, while northern sources did not set up as Tibetan Plateau uplift had not spread to Yunnan-Guizhou Plateau, so that, terrigenous mass accumulation rate was very low. Later owing to the rapid uplift of Qinghai-Tibet Plateau, rivers such as Pearl River developed gradually, so did the headward erosion, as a result, South Mainland of China turned to be the main source of ODP Site 1148, and in the meantime the northern SCS converted to distal deposition. While the hiatus of ODP Site 1148 in the late Oligocene resulted from the lack of terrigenous materials supply, sea level rise and relatively stronger currents during the source transformation. With uplift and development of Taiwan island, it turned to be the major sediment provenance of the study area since 3.5 Ma.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Cenozoic; Isotope ratios; Isotopes; Leg 184; Neogene; North Pacific; Northwest Pacific; O-18/O-16; ODP Site 1148; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Paleogeography; Plate tectonics; Quaternary; Reconstruction; South China Sea; Stable isotopes; Tectonics; Tertiary; West Pacific
Coordinates: N185010 N185010 E1163356 E1163356
Record ID: 2014037723
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland