Coeval granitic magmatism in the southern segment of the Liupanshan at the SW margin of the NCC: Implications for Paleoproterozoic extension

Abstract

The ages of the Shizuizi, Baojiashan and Duanjiaxia granites are poorly constrained. They are exposed along the southern segment of the Liupanshan fault system at the southwestern margin of the North China Craton. They form a NW-trending belt of coeval A-type granitic magmatism, characterized by high Si, alkalis, Rb/Sr, and Ga/Al. Their trace element characteristics include relative enrichments in K, Rb, and Th, and depletions in Ti, Ta, Nb, P, and Sr. Zircons from the granite yield U-Pb age of 1738 ± 15 Ma for the Baojiashan granite which has similar zircon U-Pb ages with Shizuizi (1778 Ma) and Duanjiaxia (1802 Ma) granites. The granite has negative εNd(t) of -22.5 to -20.0 and the two-stage model ages of 2.29 - 2.45 Ga. An analysis of the regional tectonics suggests that the granites were emplaced during Paleoproterozoic extension at the southwestern margin of North China Craton, where magmatism was caused by tectonic activity related to the development of the Helan aulacogen.