Geological significance of sediment provenance change in Taiwan Cenozoic sequences during opening of South China Sea

Author(s): Huang, C.; Yan, Y.; Lan, Q.
Author Affiliation(s): Primary:
Chinese Academy of Sciences, Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Guangzhou, China
Volume Title: AGU 2013 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2013; American Geophysical Union 2013 fall meeting, San Francisco, CA, Dec. 9-13, 2013. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: During opening of the South China Sea, a stratigraphic hiatus associated with a slumping interval and changes of sediment geochemistry occurs in 25-27 Ma in ODP core of Site 1148 (Wang et al., 1999). This event was considered to be driven by the C7 MOR jump (Briais et al., 1993; Wang and Li, 2009). Study on detrital zircon ages in sandstones of the Taiwan Cenozoic sequence indicates a significant change of sediment provenance occurred at 24 Ma. The data indicate that the Cathaysian Block in SE China continuously provides sediments (predominant Mesozoic Yenshanian volcanics and granites) via the Minjiang drainage system to Taiwan throughout the Cenozoic. However, the Yangtze Block in Central China starts to contribute sediments to Taiwan since the Early Miocene (≈24 Ma) as indicated by additional occurrences of 1500-2000 Ma and ≈2500 Ma age peaks of detrital zircon grains. Contributions of these older detrital zircons from the Yangtze Block are consistent with occurrences of much abundant metamorphic minerals, like kyanite, epidote, staurolite and garnet, in the Miocene post-rift sequence of Taiwan and wide exposures of Achaean and Proterozoic metamorphic rocks in the Yangtze River drainage area. This suggests that the Yangtze River might initiate at ≈24 Ma. In addition, sedimentology study further shows predominant braided river sandstones, fine conglomerates and coal measures in Taiwan Eocene syn-rift strata. This reveals that during the Eocene time the elevation in SE China-Taiwan area was much higher than the Present. This implies that the present east-tilting China geomorphology has not occurred until the Miocene/Oligocene boundary near 24 Ma. This 24 Ma event of provenance change in Taiwan Cenozoic sequences coincides with multiple tecto-stratigraphic events in Asia: a) stratigraphic hiatus, slumping, deepening of Miocene post-rift basins, changes of sediment geochemistry and C7 MOR jumping in the South China Sea, b) rapid exhumation of the Kuluan Mountain and the Longmen Shan in the N-NE Tibetan Plateau (Wang et al., 2008; Wang et al., 2012; Furlong et al., 2013), c) start of loess depositions in the Qaidam Basin north of Tibetan Plateau (Guo et al., 2002), d) initiation of the Yangtze River in E China (Zheng et al., 2013), e) dramatic change of China geomorphology from a west-tilting state in the Eocene to the present east-tilting characteristics, f) regional transgressions in SE Asian marginal seas, and g) re-organization of drainages in SE Asia (Clift et al., 2006). The mechanisms that could drive such coincided multiple events in wide area at ≈24 Ma could be a regional eastward heat flow from the Tibetan Plateau to the Asian marginal seas due to the Indian-Asian continental collision-exhumation and opening with thermal subsidence of SE Asian marginal seas related to subduction rollbacks of the Pacific and Philippine Sea Plates.
Year of Publication: 2013
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Cenozoic; Cores; Leg 184; Marine sediments; North Pacific; Northwest Pacific; ODP Site 1148; Ocean Drilling Program; Pacific Ocean; Sediments; South China Sea; West Pacific
Coordinates: N185010 N185010 E1163356 E1163356
Record ID: 2015080378
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