Intra-arc rifting induced the fragmentation of microplate from the continental margin

Abstract

Although abundant Neoproterozoic igneous rocks exposed along the periphery of the Yangtze Block of the South China Craton record the tectonic processes of the assembly and breakup of the Rodinia supercontinent, the mechanism that induced the rifting of the South China Craton from Rodinia and reconstruction of the paleogeographic position of the South China Craton in Rodinia remain controversial. We document two episodes of bimodal intrusions with emplacement ages of ca. 785 Ma and ca. 750 Ma in the Diancangshan Massif that provide critical constraints on the rifting processes and mechanisms. The rock association and the elemental and Hf-O isotopic signatures of these two episodes of bimodal intrusions illustrate that they are an important component of the Panxi-Hannan magmatic arc in the western Yangtze Block. The spatial pattern of Neoproterozoic sedimentary rocks to the west of the Panxi-Hannan arc and their provenance indicate that intra-arc rifting promoted the separation of microplates such as the Xuelongshan and Diancangshan massifs and even the Yidun Block from the western Yangtze Block and the mechanism induced synchronous deposits in these regions.