Depositional Age, Provenance Characteristics and Tectonic Setting of Gaofan Group in the Wutai Area
Addressing the debated aspects of the study on the depositional age, provenance, and sedimentary tectonic environment of Gaofan Group in the Wutai area of Shanxi, systematic sampling and detailed sedimen-tological and petrological analysis were conducted on the classic section of Gaofan Group exposed in Tanshang Town, Daixian County, Xinzhou City, Shanxi Province. Typical samples were selected for whole rock mineral composition, zircon U-Pb dating, major and trace element determinations. By analyzing detrital zircons and synthesizing previously published age data, the depositional age of Gaofan Group was considered to be approximate 2.2 Ga. This chronologic analysis showed that Gaofan Group was in a superposition relationship with the underlying Wutai Group and overlying Hutuo Group. The major and trace element composition of Gaofan Group indicated that the source rock was mainly intermediate-acidic igneous rock, suggesting that during the deposition of Gaofan Group, the upper continental crust was predominantly composed of granitoids. The age distribution of detrital zircons and tectonic discrimination diagrams based on major and trace elements of fine-grained sedimentary rocks suggested that Gaofan Group exhibited characteristics of an active continental margin. However, sedimentological analyses indicated that it was deposited in a passive continental margin with littoral and neritic facies. This contradictory conclusion may suggest that the tectonic discrimination methods derived from plate tectonic theory may not be applicable for studying the sedimentary tectonic background during the Paleoproterozoic period.
万方数据
维普
