The crust and upper mantle of the Sulu UHPM belt |
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| Authors: | Wencai Yang |
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| Institution: | Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | All results from integrated geophysical investigations in the Sulu region are summarized in this paper, trying to reconstruct the Sulu UHPM processes. New seismic S-wave tomographic results suggest a velocity-abnormal zone occurs beneath the Sulu crust, revealing detailed upper mantle structures that high-velocity lumps within the abnormal zone are sequentially distributed beneath the bottom of the asthenosphere. These high-velocity lumps might represent delaminated eclogites or residuals of the subducted oceanic plate. Based on integrated interpretation of the geophysical data, we propose a working model for tectonic reconstruction of the Sulu UHPM processes, which can explain the crust and upper mantle structures of the area. The involved tectonic processes are related to north-eastward escaping of the Sulu terrane, subduction and delamination cycles of the Dabie-Sulu oceanic plate, and post-orogenic lithospheric thinning and magma underplating. The UHPM rocks are believed to have syn-subduction delaminated down to the bottom of the asthenosphere during 245-180 Ma, and the delamination process seemed smooth and nearly continuous without extensive violence. |
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| Keywords: | Ultrahigh-pressure belt Sulu of eastern China S-wave tomography Deep seismic reflection Crust and mantle structures Tectonic reconstruction model |
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