2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 86-2
Presentation Time: 8:15 AM

NEOPROTEROZOIC OROGENY-RELATED MAGMATIC EVENT IN THE NORTHWESTERN YANGTZE BLOCK AND ITS IMPLICATIONS FOR THE UNIFICATION OF SOUTH CHINA


WAFA, Berkana and LING, Wenli, State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Faculty of Earth Sciences, China University of Geosciences, state key laboratory of geological process and mineral resources, china university of geosciences, wuhan 430074, china, faculty of earth sciences, china university ofgeosciences, wuhan 430074, china, Wuhan, 430074, China

Neoproterozoic tectonic history of South China has long been an issue of debate, including its connection with the cycle of Rodinia. The South China block has been traditionally thought to have formed by Neoproterozoic welding between the Yangtze and Cathysian blocks along the Jiangnan Orogen. However, increasing evidence suggests that the Neoproterozoic unification of South China comprises a set of collision events. Here we report a newly recognized syn-collisional intrusive suite at the northwestern Yangtze block.

The igneous suite is located at the Wangcang area, NE Sichuan province. It consists of tholeiitic- and alkali mafic rocks, and adakitic to calc-alkali felsic intrusions. They are dated at 8554Ma to 8675 Ma by U-Pb zircon, and show arc-related geochemical affinities with highly variable whole rock εNd (up to +7.78) and zircon εHf(t) values. The Wangcang suite is featured by high deformation and metamorphism of upper greenschist to amphibolitic facieses, which is contrast to the low grade ~820-750 Ma igneous suites in the same region. It suggests that the northwestern Yangtze block experienced an arc-continental orogenic event occurred during ~860-820 Ma.

Our recent work has revealed that the Shennongjia terrain and the Yangtze continental nucleus was welded between ~1100-950Ma. These findings suggest that the unification of South China comprises a set of collision events. This work provides a new clue for our understanding of the connection between the Neoproterozoic evolution of South China and Rodinia cycle.

This study was supported by the NSFC (Grants 41173048 and 41373037).

Session No. 86

Crustal Deformation Processes—From Orogens and Oroclines to Meteorite Impacts: Recent Advances Based on Field and Modeling Studies
Monday, 20 October 2014: 8:00 AM-12:00 PM
214 (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.225
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