Metamorphic P-T paths of different tectonic domains in the North China Craton and their implications

Abstract

North China Craton (NCC) had been well studied by expertise for years, yet the evolution history and nature of formation of different tectonic domain is still remained controversial caused by complex deformation series associated with multiple thermotectonic event in different tectonic settings between Late Archean and Paleoproterozoic. Exposures of basement rock commonly have been reworked and metamorphosed from ancient crustal rock in 2.6-2.5Ga, which constrained and limited source and evidence of the early Archean formation. Nonetheless, previous studies and reviewed models from recent researches had reconstructed the evolution model of the NCC. In this paper, metamorphic P-T paths from each tectonic domains were studied associated with the nature of the exposures including chemical composition, lithotectonic assemblages, phase equilibrium and geochronology information, the evolution of the NCC can be summarized into four major thermotectonic period; (1) 2.8-2.7Ga major juvenile crustal growth of the basement rock defined by clockwise PT path including greenstone belt and wide spread TTG gneiss; (2) 2.6-2.5Ga closure of ancient ocean led to collision in Eastern Block associated with accretionary prism defined by anticlockwise P-T path from Longgang block and further tectonism developed the Jiao-Liao-Ji belt characterized by clockwise P-T path; (3) 1.95-1.9Ga evolution of the E-W trending Khondalite belt triggered by the collision between the Yinshan block and Ordos basin characterized by clockwise P-T path associated with crustal thickening and anticlockwise P-T path developed by isothermal decompression followed by isobaric cooling respectively; (4) 1.85Ga Extensional thermotectonism leading to the closure of the east dipping ocean slab that developed a TNCO in between the Western block and Eastern block with major faults defining the boundaries, and finish of the closure led to final amalgamation of the NCC in 1.8Ga.