New SHRIMP U-Pb age from the Wuqiangxi Formation of Banxi Group: Implications for rifting and stratigraphic erosion associated with the early Cryogenian (Sturtian) glaciation in South China |
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Authors: | ShiHong Zhang GanQing Jiang Jin Dong YiGui Han HuaiChun Wu |
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Institution: | (1) State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, 100083, China;(2) Department of Geoscience, University of Nevada, Las Vegas, Nevada 89154-4010, USA |
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Abstract: | In South China, the Wuqiangxi Formation of the Banxi Group and its equivalents underlie the early Cryogenian (Sturtian) glacial
deposits but their thickness varies from <200 m to >2000 m. In the Guzhang section of western Hunan, the Wuqiangxi Formation
is only 152 m thick, and an ash bed 58 m below the glacial diamictite yielded a SHRIMP U-Pb age of 809.3±8.4 Ma. In contrast,
90 km south of the Guzhang section towards the basin in Zhijiang area where the Wuqiangxi Formation is ∼2200 m thick, an age
of 725±10 Ma has been reported from the top of this unit, 300 m below the glacial diamictite. These ages provide new evidence
for the regional stratigraphic correlation across the Nanhua basin, and suggest unusually large (>2 km) stratigraphic erosion
potentially associated with the Sturtian glaciation in South China. The magnitude of erosion may imply significant uplifting
and tectonotopography at the onset of the Sturtian glaciation.
Supported by the National Natural Science Foundation of China (Grant Nos. 40621002, 40572019), Ministry of Education of China
(Grant Nos. IRT0546, NCET-04-0727, “111” Project B07011) and the National Science Foundation of USA (Grant No. EAR 0745825) |
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Keywords: | Neoproterozoic Banxi Group SHRIMP U-Pb age Sturtian glaciation South China |
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