Neoproterozoic–Mesozoic Tectono-Magmatic evolution of the northern Dabie Orogen, eastern China

Abstract

The Dabie orogen was generated by the Late Triassic collision of the North China and South China continents and is important for understanding (ultra)high-pressure metamorphism related to continental subduction. The peak (ultra)high-pressure metamorphism related to this collisional event was followed by Late Jurassic to Early Cretaceous magmatism that generated widespread igneous rocks throughout eastern China. Despite numerous studies on these events during the evolution of the Dabie orogen, other critical issues concern the nature of Proterozoic basement rocks and the Mesozoic tectono-magmatic evolution of the orogen. In this contribution, we synthesize field relationships, crystallization and depositional ages, elemental and Sr–Nd isotopic analyses from the Shangcheng area of the northern Dabie orogen. Our study demonstrates that the northern Dabie orogen contains mid-Neoproterozoic crystalline basement composed of ca. 767–733 Ma granitoids that resemble those of the Yangtze craton. Based on detrital zircons ages, we interpret that the North China continent and Yangtze craton of the South China continent were linked in the Devonian. This was followed by opening of an ocean basin between the continents in the Carboniferous and subsequent ocean closure by Jurassic time. Emplacement of ca. 137–130 Ma adakites in the Dabie orogen is interpreted to be related to regional crustal thickening. This crustal thickening phase was followed by emplacement of ca. 130–121 Ma intermediate igneous rocks during regional extension, which is supported by paleo-crustal thickness trends and the presence of an unconformity between the Cretaceous Shangcheng pluton and overlying volcanic rocks of the Jingangtai Formation.