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| Titel |
The formation of post-spreading volcanic ridges in the South China Sea |
| VerfasserIn |
Minghui Zhao, Jean-Claude Sibuet, Enyuan He, Pingchuan Tan, Jian Wang, Xuelin Qiu |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123901
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| Publikation (Nr.) |
 EGU/EGU2016-3239.pdf |
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| Zusammenfassung |
| In the South China Sea (SCS), the post-spreading magmatism (∼8-13 Ma) largely masks
the previous spreading fabric. The resulting post-spreading seamounts are more
numerous in the northern part than in the southern part of the East sub-basin. In the
eastern part of the East sub-basin, the post-spreading volcanic ridge (PSVR) is
approximately N055˚ oriented and follows the extinct spreading ridge (ESR). In
the western part of the East sub-basin, the PSVR, called the Zhenbei-Huangyan
seamounts chain, is E-W oriented and hides the ESR. Based on swath bathymetric and
magnetic data, the ESR in the eastern part of the East basin is also N055˚ oriented
and thus is oblique the E-W Zhenbei-Huangyan seamounts chain (Sibuet et al.,
2016).
We conducted a seismic refraction survey covering both the Zhenbei-Huangyan
seamounts chain and the adjacent ESR, providing new constraints for understanding the
relationship between the PSVR and the ESR. The detailed velocity structure shows that the
Zhenbei-Huangyan seamounts chain was emplaced through a typical oceanic crust. The
thicknesses of Zhenbei (14 km) and Huangyan seamounts (8 km) are larger than the ones of
the normal oceanic crust. The correlation between crustal thicknesses and mean lower-crustal
seismic velocities suggest that an asymmetric generation of seamounts in the East sub-basin
where active upwelling mantle (Holbrook et al., 2001), the presence of a fertile mantle
component (Korenaga et al., 2002), or buoyancy-driven decompression melting
may happened (Castillo et al., 2010). Below the seamounts, the thickened lower
crust is probably due to secondary magmatic intrusions and the large thickness of
upper crust is possibly due to volcanic extrusions. The crustal thicknesses as well
as the mean lower-crustal velocities of the Zhenbei and Huangyan seamounts are
different, suggesting an independent origin for magmatic feeding. This research
was granted by the Natural Science Foundation of China (91028002, 91428204,
41176053).
References
Sibuet J.-C., Yeh Y.-C. and Lee C.-S., 2016 revised. Geodynamics of the South China
Sea. Tectonophysics.
Holbrook, W. S., H. C. Larsen, J. Korenaga, et al., 2001. Mantle thermal structure and
active upwelling during continental breakup in the North Atlantic, Earth Planet. Sci. Lett.,
190, 251-266.
Korenaga, J., P.B.Kelemen, W.S. Holbrook., 2002. Methods for resolving the origin of
large igneous provinces from crustal seismology. Journal of Geophysical research: Solid
Earth (1978-2012), 107(B9), 2178,doi:10.1029/2001JB001030.
Castillo, P. R., Clague, D. A., Davis, A. S., et al., 2010. Petrogenesis of Davidson Seamount
lavas and its implications for fossil spreading center and intraplate magmatism in the eastern
Pacific. Geochemistry, Geophysics, Geosystems, 11, Q02005, doi:10.1029/2009GC002992. |
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