Seismic Evidence for a Geosuture between the Yangtze and Cathaysia Blocks, South China

Chuansong He,Xuanhua Chen,M Santosh,Shuwen Dong

doi:10.1038/srep02200

Abstract

South China, composed of the Yangtze and Cathaysia Blocks and the intervening Jiangnan orogenic belt, has been central to the debate on the tectonic evolution of East Asia. Here we investigate the crustal structure and composition of South China from seismic data employing the H-k stacking technique. Our results show that the composition and seismic structure of the crust in the Jiangnan orogenic belt are identical to those of the Cathaysia Block. Our data reveal a distinct contrast in the crustal structure and composition between the two flanks of the Jiujiang-Shitai buried fault. We propose that the Jiujiang-Shitai buried fault defines a geosuture between the Yangtze and Cathaysia Blocks, and that the felsic lower crust of the Cathaysia Block and the Jiangnan orogenic belt may represent fragments derived from the Gondwana supercontinent.

Highlights

South China, composed of the Yangtze and Cathaysia Blocks and the intervening Jiangnan orogenic belt, has been central to the debate on the tectonic evolution of East Asia
We propose that the Jiujiang-Shitai buried fault defines a geosuture between the Yangtze and Cathaysia Blocks, and that the felsic lower crust of the Cathaysia Block and the Jiangnan orogenic belt may represent fragments derived from the Gondwana supercontinent
The Jiangnan orogenic belt and the Cathaysia Block are characterized by lower Vp/Vs ratio of 1.66–1.73, as compared to the Vp/Vs ratios of 1.74–1.79 in the SECCLMVZ (Southeast China coastal late Mesozoic volcanic zone)

Summary

Introduction

South China, composed of the Yangtze and Cathaysia Blocks and the intervening Jiangnan orogenic belt, has been central to the debate on the tectonic evolution of East Asia. The South China Block is composed of two sub-blocks, the Yangtze in the NW and Cathaysia in the SE (Figure 1), which collided and amalgamated during the Neoproterozoic, giving rise to the Jiangnan Orogen[1,2,3,4,5,6,7,8,9,10]. Collision zones such as this are critical to our understanding of orogenic process and the evolution of the continents[11,12].

Methods

Results

Conclusion