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Crustal-scale Structure of the Eurasian Continental Margin in the Northern South China Sea, Offshore Taiwan from Seismic Reflection and Wide-angle OBS Data
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lester, W. Ryan Mcintosh, Kirk Avendonk, H. J. Van |
| Copyright Year | 2010 |
| Abstract | Multi-channel seismic reflection data and wide-angle OBS data collected in 2009 offshore southwest Taiwan as part of the TAIGER program delineate the crustal structure of the Eurasian rifted continental margin in the northern South China Sea. Geophysical studies in central and southwest South China Sea have revealed the Eurasian margin to be a wide, structurally complex margin, with variable associated volcanic activity. The new TAIGER active source seismic data provide some of the first high-resolution crustal-scale constraints on the opening of the South China Sea basin near present-day Taiwan, as well as images of crustal materials that may serve as analogs for the materials involved in the formation of the nearby Taiwan mountain belt. The new reflection imaging and travel-time tomography show 3-4 km of passive margin sediments overlying continental crust over 20 km thick. Listric normal faults along the continental shelf offset shallow sediments and penetrate deep into the crust. At the base of the continental slope, a necking zone where crust thins to ~4 km is observed in both a travel-time tomography velocity model and reflection images. This necking zone is characterized by a rapidly shoaling Moho, a half-graben structure in the thinned crust, thick sediments and local volcanic activity. Crust thickens gradually basin-ward to 10-12 km thick. While this thickness is consistent with observations from previous potential field studies, seismic velocities of this crustal block are consistent with transitional crust elsewhere in the South China Sea, rather than anomalously thick ocean crust as has been previously inferred. Instead, these new data suggest a zone of seamounts at ~ 20° latitude may serve as the boundary between the block of 10-12 km thick transitional crust to the north and normal ocean crust of the South China Sea basin to the south. Future geophysical imaging and modeling efforts may shed light on the tectonic history of the South China Sea and the influence of pre-existing margin structure on mountain-building processes in Taiwan. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.ig.utexas.edu/people/staff/kirk/projects/taiger/presentations/lester2010.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
