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  

作　　者：ZHANG ShiHong JIANG GanQing DONG Jin HAN YiGui WU HuaiChun 

机构地区：[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

出　　处：《Science China Earth Sciences》2008年第11期1537-1544,共8页中国科学（地球科学英文版）

基　　金：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);the National Science Foundation of USA (Grant No. EAR 0745825)

摘　　要：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.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 &lt;200 m to &gt;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 (&gt;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.

关 键 词：NEOPROTEROZOIC Banxi Group SHRIMP U-Pb age Sturtian GLACIATION South China 

分 类 号：P535[天文地球—古生物学与地层学]