P Wave Velocity Structure and Tectonics Analysis of Lithospheric Mantle in Eastern China Seas and Adjacent Regions

Abstract

Using earthquake data recorded by seismic stations in the eastern China and Taiwan areas, Japan and Ryukyu Arcs, we reconstructed the P wave velocity structure of the eastern China seas and adjacent areas through a seismic tomography inversion. By analyzing the properties of lithosphere mantle and deep dynamic conditions in these regions, we discussed the locations of the boundaries between the Sino-Korea, Yangtze and South China blocks. They revealed the effects of the collision of Philippine Sea plate with Eurasian continent, slab subduction, and back-arc extension on the lithosphere structure of the eastern China seas. The results also revealed a strong lateral heterogeneity of the lithosphere mantle in the eastern China seas and it has a certain relation with regional tectonics. The Wulian-Qingdao fault zone, the west-margin fault zone of Korea Peninsula and the south-margin fault zone of the Cheju Island jointly construct the boundary between the Sino-Korea and Yangtze blocks. Extending to the south end of the Korea peninsula, the Jiangshao fault zone appears as the boundary to separate the Yangtze and South China blocks. A clear difference in lithosphere structure exists for the continental shelf of the East China Sea and the Okinawa Trough. The former is similar to that in eastern China, belonging to an extension of the Eurasian continent; whereas the latter is a continent-ocean transition zone with a strongly thinned lithosphere. Along the Ryukyu-Taiwan subduction zone, the sinking of the Philippine Sea plate has a great effect on the upper mantle structures of the eastern China seas, while the interaction between the Eurasian continent and the Philippine Sea plate is a major reason for the thickening of the lithosphere of Taiwan area.

Mesozoic magmatic activity and tectonic evolution in the southern East China Sea Continental Shelf Basin: Thermo‐mechanical modelling

“…(Zhu, Cao, & Yan, ). What is more, the existence of the low‐velocity lithospheric mantle in the Western Pacific can be found several sections (Cheng, Zhu, & Cai, ; Liu et al, ; Xu, Liu, Hao, Liu, & Li, ). Coevally, the upwelling of the hot mantle causes a thinning of the upper crust, which also contributes to the further descent of the settlement centre.…”

Crustal Poisson’s ratio anomalies in the eastern part of North China and their origins

“…Research on P-wave seismic tomography started from the 1980s onwards with several reports published since then (Liu et al, 1986;Zhao et al, 1992;Huang and Zhao, 2005;Xu et al, 2006). S-wave seismic tomography is also a primary method to study the fabric of the upper mantle, although this was initiated only later due to difficulties with the technique (Pei et al, 2004;Xu and Zheng, 2005;Zhang et al, 2006;Ji et al, 2007;Yang et al, 2007;Ji et al, 2009).…”

“…For nearly 30 years the fact that seismic tomography can be utilized to investigate both fine P-wave and S-wave velocity structures of the crust and upper mantle has gained world-wide acknowledgment (Liu et al, 1986;Nolet, 1987;Yang, 1989;Zhao et al, 1992;Yang and Li, 1993;Nolet and Ziehuis, 1994;Pei et al, 2004;Huang and Zhao, 2005;Xu et al, 2006;Zhang et al, 2006;Yang et al, 2007). The Poisson's ratio image of the crust and upper mantle can be determined by proper computation after P-wave and S-wave velocity imaging.…”

East Marginal Fault of the Yellow Sea: a part of the conjunction zone between Sino‐Korea and Yangtze Blocks?

“…The velocity profile crossing the southern end of the Korean Peninsula ( Fig. 6; Xu et al 2006) shows that above 100 km the fault is very steep, and below 100 km it dips towards the west. It should be noticed that the P-velocity image of the Korean Peninsula on the east side of the EMFYS shows high velocity above 200 km, which is obviously different from the velocity distribution in the southern Yellow Sea on the west side of the EMFYS.…”