Magnetotelluric evidence for the multi-microcontinental composition of eastern South China and its tectonic evolution

Abstract

The tectonic boundaries and geodynamic evolution of the South China Block are widely debated. While the community largely agrees on the occurrence of the collision between the Yangtze and Cathaysia Blocks, the lack of ultrahigh-pressure metamorphic rocks and obscurity of the boundary lead to inconsistencies among the abundant geological and geophysical data. We present three profiles that reveal the geoelectrical structure of eastern South China. Distinct conductive interfaces oriented NE-SW are identified in the geoelectrical lithosphere, which separate the region into six parts. To interpret our observations and resultant model, we develop and propose a mechanism of "microcontinent interaction". Our new model justifies the prior proposed models of 'block collision' and additionally proposes 'multi-terrane accretion-collision' to address the tectonic evolution.