Abstract
Magnetic data suggest that the distribution of the oceanic crust in the northern South China Sea (SCS) may extend to about 21 °N and 118.5 °E. To examine the crustal features of the corresponding continent–ocean transition zone, we have studied the crustal structures of the northern continental margin of the SCS. We have also performed gravity modeling by using a simple four-layer crustal model to understand the geometry of the Moho surface and the crustal thicknesses beneath this transition zone. In general, we can distinguish the crustal structures of the study area into the continental crust, the thinned continental crust, and the oceanic crust. However, some volcanic intrusions or extrusions exist. Our results indicate the existence of oceanic crust in the northernmost SCS as observed by magnetic data. Accordingly, we have moved the continent–ocean boundary (COB) in the northeastern SCS from about 19 °N and 119.5 °E to 21 °N and 118.5 °E. Morphologically, the new COB is located along the base of the continental slope. The southeastward thinning of the continental crust in the study area is prominent. The average value of crustal thinning factor of the thinned continental crust zone is about 1.3–1.5. In the study region, the Moho depths generally vary from ca. 28 km to ca. 12 km and the crustal thicknesses vary from ca. 24 km to ca. 6 km; a regional maximum exists around the Dongsha Island. Our gravity modeling has shown that the oceanic crust in the northern SCS is slightly thicker than normal oceanic crust. This situation could be ascribed to the post-spreading volcanism or underplating in this region.
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References
V. Benes N. Bocharova E. Popov S.D. Scott L. Zonenshain (1997) ArticleTitleGeophysical and morpho-tectonic study of the transition between seafloor spreading and continental rifting, western Woodlark Basin, Papua New Guinea Marine Geol. 142 85–98 Occurrence Handle10.1016/S0025-3227(97)00042-X
A. Briais P Patriat P. Tapponnier (1993) ArticleTitleUpdated interpretation of magnetic anomalies and seafloor spreading stages in the South China Sea. Implications for the tertiary tectonics of Southeast Asia J. Geophys Res 98 6299–6328
Clift P.D, Lin J, ODP Leg 184 Scientific Party, 2001, Patterns of extension and magmatism along the continent-ocean boundary, South China margin, in: Wilson, et al. R. C. (ed.) Non-Volcanic Rifting of Continental Margins: a Comparison of Evidence from Land and Sea, Geological Society, London, Special Publication 187, 489–510.
Henkart, P., 1992, SIOSEIS – a Computer System for Enhancing and Manipulating Marine Seismic Reflection and Refraction Data, Scripps Institute of Oceanography.
S.-K Hsu C.-S Liu C.-T Shyu S.-Y Liu J.-C Sibuet S Lallemand C Wang D. Reed (1998) ArticleTitleNew gravity and magnetic anomaly maps in the Taiwan-Luzon region and their preliminary interpretation TAO 9 509–532
Hsu, S.-K., Yeh, Y.-C., Doo, W.-B. and Tsai, C.-H., 2005, New identification of magnetic lineations and bathymetry in the Northernmost South China Sea and their tectonic insights, Marine Geophys. Res. (this issue).
Y. Kido K. Suyehiro H. Kinoshita (2001) ArticleTitleRifting to spreading process along the Northern continental margin of the South China Sea Marine Geophys. Res. 22 1–15 Occurrence Handle10.1023/A:1004869628532
Lin, A. T. and Watts, A. B., 2002, Origin of the west Taiwan basin by orogenic loading and flexure of a rifted continental margin, J. Geophys. Res. 107, doi:10.1029/2001 JB000669.
T. Ludmann H. K. Wong (1999) ArticleTitleNeotectonic regime on the passive continental margin of the northern South China Sea Tectonophysics 311 113–138
T. Ludmann H.K. Wang P. Wang (2001) ArticleTitlePlio-Quaternary sedimentation processes and neotectonics of the northern continental margin of South China Sea Marine Geol. 172 331–358 Occurrence Handle10.1016/S0025-3227(00)00129-8
W.J. Ludwig N. Kumar R.E. Houtz (1979) ArticleTitleProfiler-sonobuoy measurements in the South China Sea Basin J. Geophys. Res. 84 3505–3518
R. Mjelde S. Kodaira R.K. Hassan A. Goldschmidtrokita N. Tomita M.A. Sellevoll H.B. Hirschleber H. Shimamura T. Iwasaki T. Kanazawa (1996) ArticleTitleThe continent/ocean transition of the Lofoten volcanic margin, N Norway. J. Geodyn. 22 189–206 Occurrence Handle10.1016/0264-3707(96)00016-6
S.S. Nissen D.E. Hayes P. Buhl J. Diebold B. Yao W. Zeng Y. Chen (1995a) ArticleTitleDeep penetration seismic soundings across the northern margin of the south China Sea J. Geophys. Res. 100 22407–22433 Occurrence Handle10.1029/95JB01866
S. S. Nissen D. E. Hayes B. Yao W. Zeng Y. Chen X. Nu (1995b) ArticleTitleGravity, heat flow, and seismic constraints on the processes of crustal extension: Northern margin of the South China Sea J. Geophys. Res. 100 22447–22483 Occurrence Handle10.1029/95JB01868
L. M. Pinheiro R. C. L. Wilson R. Pena dos Reis R. B. Whitmarsh A. Ribeiro (1996) ArticleTitleThe western Iberia margin: a geophysical and geological overview Proceedings of the Ocean Drilling Program: Scientific Results 149 3–23
D. T. Sandwell W. H. F. Smith (1997) ArticleTitleMarine gravity anomaly from Geosat and ERS-1 satellite altimetry J. Geophys. Res. 102 10039–10050 Occurrence Handle10.1029/96JB03223
J.-C. Sibuet S.-K. Hsu (1997) ArticleTitleGeodynamics of the Taiwan arc–arc collision Tectonophysics 274 221–251 Occurrence Handle10.1016/S0040-1951(96)00305-8
J.-C. Sibuet S.-K. Hsu X. L. Pichon J. P. L. Formal D. Reed G. Moore C.-S. Liu (2002) ArticleTitleEast Asia plate tectonics since 15 Ma: Constraints from the Taiwan region Tectonophysics 344 103–134 Occurrence Handle10.1016/S0040-1951(01)00202-5
J.-C. Sibuet V. Louvel R. B. Whitmarsh R. S. White S. J. Horsefield B. Sichler P. Leon M. Recq (1995) Constraints on Rifting Processes from Refraction and Deep-Tow Magnetic Data: The Example of the Galicia Continental Margin (West Iberia) Rifted Ocean-Continent Boundaries. Kluwer Academic Publishers Netherlands 197–218
B. Taylor D. E. Hayes (1983) Origin and history the South China Sea D. E. Hayes (Eds) The Tectonic and Geologic Evolution of Southeast Asia Seas and islands, 2, Geophysical Monographic Series, 27 AGU Washington DC
P. Wessel W. H. F. Smith (1995) ArticleTitleNew version of the Generic Mapping Tools released Eos Trans., AGU (Suppl.) 76 329
P. Yan D. Zhou Z. Liu (2001) ArticleTitleA crustal structure profile across the northern continental margin of the South China Sea Tectonophysics 338 1–21 Occurrence Handle10.1016/S0040-1951(01)00062-2
B. Yao W. Zeng D. E. Hayes S. Spangler (1994) The Geological Memoir of South China Sea Surveyed Jointly by China and the U.S.A. The Press of Chinese Geological University Wuhan
H.-S. Yu Y.-W. Chou (2001) ArticleTitleCharacteristics and development of the flexural forebulge and basal unconformity of western Taiwan foreland basin Tectonophysics 333 277–291 Occurrence Handle10.1016/S0040-1951(00)00279-1
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Tsai, CH., Hsu, SK., Yeh, YC. et al. Crustal Thinning of the Northern Continental Margin of the South China Sea. Mar Geophys Res 25, 63–78 (2004). https://doi.org/10.1007/s11001-005-0733-5
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DOI: https://doi.org/10.1007/s11001-005-0733-5