Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China;Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China;Chinese Acad Geol Sci, Inst Geol, Beijing, Peoples R China;
Li, Yongchen;Xiao, Wenjiao;Tian, Zhonghua;
The Datong area is located in the western part of the Western Kunlun Orogen (WKO), occupying a key area of the Tethyan domain. Our new SHRIMP U-Pb zircon ages from the Datong area provide new information about the Palaeozoic evolution of the Western Kunlun Orogen. A 473.0 +/- 2.8Ma granite with 493.6 +/- 4.8Ma inherited zircons from the Kusilafu extrusive rocks is interpretation as an A-type granite formed in a fore-arc tectonic setting. The 485.5 +/- 1.9Ma granitoid of the Datongdong pluton combined with the 452.7 +/- 7Ma granitoid of the Datong pluton indicate that the Datong pluton is an intra-oceanic arc complex formed by the southern subduction of the Proto-Tethyan ocean crust. Zircons from gabbros of the Datong mafic-ultramafic complex have a 499.2 +/- 2.1Ma U-Pb crystallization age. Combined with its complicated whole-rock geochemistry, we propose that there may have existed a Datong seamount in the early Palaeozoic. The detrital zircon results of Silurian-Devonian sandstones reveal that the Late Silurian sandstones have the characteristic zircons both from the Tarim Block and Datong Arc, suggesting that the Datong arc collided with the Tarim Block in the Late Silurian. The tectonic history of the WKO was characterized by a southern subduction of Proto-Tethys terminated in the Late Silurian.