A possible buried Paleoproterozoic collisional orogen beneath central South China: Evidence from seismic-reflection profiling

摘要

The South China Craton consisting of the Yangtze and Cathaysia Blocks has figured importantly in the Neoproterozoic supercontinent of Rodinia. However, its lack of Grenville-age structures and metamorphism and the presence of Paleoproterozoic high-grade metamorphism and S-type magmatism raise questions about the timing and nature of the Yangtze-Cathaysia collision. Here we present results of a 400-km-long high-resolution seismic reflection profile across the purported suture between the Yangtze and Cathaysia Blocks. The seismic profile reveals folded and thrust-imbricated seismic reflectors which we interpret to represent the relics of the Yangtze-Cathaysia collisional orogen. The inferred orogen was extended in the Neoproterozoic, resulting in its burial by Neoproterozoic flysch strata. Geochronological data suggest that this buried orogen was formed in the Paleoproterozoic (similar to 2.0-1.9 Ga), likely associated with the assembling of the Columbia supercontinent. These results call for major revision of the models for the formation of the South China craton and its role in the assembling of the Rodinia and the Columbia supercontinents. (C) 2015 Elsevier B.V. All rights reserved.