Neoproterozoic Arc - related mafic intrusions along the Northern Margin of South China: implications for accretion of Rodinia

Abstract

South China has been considered as part of the Rodinian supercontinent during Neoproterozoic time, although itspaleogeographic position within this supercontinent is still a matter of debate. The Wangjiangshan and Bijigou complexesalong the northern margin of South China are among the largest mafic intrusions in China. New SHRIMPzircon U-Pb results indicate that these two intrusions have crystallization ages of 820 Ma and 780 Ma, respectively.Enrichment of large ion lithophile and light rare earth elements and depletion of high field-strength elements in theseintrusions suggest derivation from an active arc along a continental margin. This interpretation of these intrusionsas part of a continental arc assemblage is in contrast with the previous view that they were products of a Neoproterozoicmantle plume that initiated the breakup of Rodinia. The presence of a Neoproterozoic magmatic arc suggests thatRodinian oceanic lithosphere was subducted beneath the (present) northern margin of South China and therefore thatSouth China flanked the Rodinian ocean.