The uplift of Fuping Complex and its implications for the late Paleoproterozoic evolution of the North China Craton

Abstract

The Paleoproterozoic is a key period in the evolution of the North China Craton, involving major tectonic events such as the cratonization and the transition of the tectonic regime. Previous study showed that the continent–continent collision occurred during the late Paleoproterozoic (∼1.85 Ga), which is related to the amalgamation of the Eastern and Western blocks. However, the anorogenic magmatism and intra-continental rifts indicated the extensional setting after the collision. Therefore, the tectonic regimes of the North China Craton underwent the transition from compression to extension during the late Paleoproterozoic. In this paper, it is proposed by authors that the uplift of the Fuping Complex occurred under the extensional setting during the late Paleoproterozoic, which probably indicate the original manifestation and initial time of the Meso- to Neoproterozoic extension in the North China Craton. Main evidences suggested by author are listed as follows. (1)The low-angle deformation zone developed on the northwest margin of the Fuping Complex, including the Longquanguan shear zone, Wangmaoshan folded deformation layer and Xiaomai shear zone. Various asymmetrical indicators in these structures showed the top-to-the-NW or W sense of shearing. (2) Based on constraints from different kinds of dating results, the deformation time of Longquanguan shear zone is constrained in period 1.83 ∼ 1.78 Ga, which is later than the collision along the Trans-North China Orogen (∼1.85 Ga), while earlier than the occurrence of the Xiong’er Group (1.78 ∼ 1.75 Ga) in the Xiong’er rift. Meanwhile, the Pingshan shear zone on the southeastern margin of Fuping Complex showed the top-to-the-SE shearing which deformed synchronously with Longquanguan shear zone. The uplift of Fuping complex is confirmed by the fact that it was sandwiched by two low-angle shear zones with different shearing orientation on its northwest and southeast margins. The author proposed that the uplift process is probably the result of the magma diapirism, which is related to the lithospheric dissociation of North China Craton along with the breakup of the Columbia Supercontinent.