Structure of mantle transition zone beneath South China Block and its dynamic significance
South China Block,influenced by both the Tethys tectonic domain and the Pacific tectonic domain,is one of the key areas for studying plate interactions.To study the deep dynamic process beneath South China Block,based on broadband seismic data(south of 30°N)recorded by the national permanent seismic network,we image the mantle transition zone(MTZ)structure beneath the South China Block using receiver function methods,and discuss the division of deep tectonic units and their shallow structural responses combined with the existing geological and geophysical data.Our results indicate:(1)The MTZ structure beneath the Yangtze craton approaches the global average and is relatively stable;(2)The thickness of the MTZ beneath Hainan Island is relatively thin,with significant subsidence and uplift of the 410-km and 660-km interfaces,respectively,possibly related to the Hainan mantle plume;(3)The deep tectonic boundary between Pacific tectonic domain and Tethys tectonic domain is significant.The southeastern margin of the Tibetan Plateau is mainly affected by the Tethys tectonic domain,and delaminated lithospheric slabs may remain in the MTZ;(4)The area to east of the Xuefeng mountain is mainly influenced by the Pacific tectonic domain,with local differences between the north and south part.There may be no stagnated plate under the Cathaysian Block.The subduction and retreat of the Pacific plate are closely related to the crustal thinning and large-scale exposure of Mesozoic-Cenozoic magmatic rocks in the southeast coastal area.
South China BlockReceiver functionPlate subductionMantle transition zoneMantle plume
万方数据
维普
