Neoproterozoic Low-δ 18 O Zircons Revisited: Implications for Rodinia Configuration

Abstract

Neoproterozoic magmatic rocks and detrital zircons with low-δ 18 O values were frequently identified in the Yangtze Block, Madagascar, and India. Here we first report Neoproterozoic low-δ 18 O zircons from the central part of the Cathaysia Block in South China. These zircons include detrital grains from the Early Paleozoic metamorphic rocks, inherited domains from the Early Paleozoic granitic rocks, and igneous ones from the Neoproterozoic volcanic rocks. In combination with the available data for Neoproterozoic 18 O-depleted magma and zircons worldwide, we conclude that, globally, 18 O-depleted magmatic activities generally began after 800 Ma and reached the peak at 780–760 Ma, corresponding to the rifting of Rodinia supercontinent. The occurrence of low-δ 18 O magmatism after approximately 730 Ma in the northern Yangtze Block possibly indicates extended rifting that was associated with Neoproterozoic glaciations. The similarity in low-δ 18 O magmatism between northwest India, Madagascar, and South China suggests close connections in the Rodinia supercontinent during the middle Neoproterozoic.