Depositional Age, Provenance and Tectonic Significance of the Huodiya Group in Wangcang Area, Northwestern Margin of the Yangtze Block: Constraints from Detral Zircon U-Pb Geochronology

Key words: 
• Huodiya Group /
• depositional age /
• provenance /
• zircon U-Pb dating /
• Northwestern margin of the Yangtze Block /
• Neoproterozoic

Abstract: The Huodiya Group is an important Precambrian stratigraphic unit in the northwestern margin of the Yangtze Block and a significant graphite-bearing stratum in China. However, its depositional age, provenance and tectonic attribution have been controversial for a long time. In this paper, LA-ICP-MS zircon U-Pb dating were carried out on the sericite phyllite from the Shangliang Formation of Huodiya Group, Wangcang area. The results show that maximum depositional age of the sample is 837.6 ± 6.0 Ma (MSWD = 0.60, n = 5). Combined existing data, the depositional age of Huodiya Group is constrained between ~910 Ma and ~835 Ma. The age populations of detrital zircons are concentrated in the four peaks of 832-843 Ma, 855-883 Ma, 895-936 Ma and 952-988 Ma, and the detrital provenance is mainly from the southeast and northwest magmatic rocks. A synthesis of depositional age, provenance and regional geological background, the Shangliang Formation of Huodiya Group in Wangcang area probably deposited in the backarc basin receiving provenance from both sides, which is a response to the late-stage convergence of the Rodinia supercontinent in the northwestern margin of the Yangtze Block.