The Cu–Au–Mo deposit mineralization dynamics at the northern margin of the North China Craton and the southeastern margin of the Central Asian Orogenic Belt based on crustal oxide content

Abstract

The study of the mineralization dynamics of the Cu–Au–Mo deposit at the northern margin of the North China Craton and the southeastern margin of the Central Asian Orogenic Belt is important for understanding metallogenic settings. We calculated the crustal oxide content in heterogeneous systems using crustal temperature, seismic wave velocity (V_p), pressure and 1 wt.% water content. The oxide contents of SiO₂, MgO, K₂O and Na₂O in the crust from 10 to 40 km depth were obtained. The Bohai Bay Basin, Yanshan Block and Songliao Basin in the eastern study area exhibit an upper mantle lithology characterized by low SiO₂ and high MgO at 40 km, suggesting that the lithosphere in this area has been thinned. The destruction of the lithosphere was accompanied by the upwelling of the asthenosphere and upper mantle and the underplating of the lower crust by thermal material. Eventually, the crust formed mineralized fluids rich in volatiles, metallic elements and high oxygen fugacity. There is a good correspondence between the mineralization, the medium acidic, high alkali and low Mg–Fe regions in the lower crust and the extensional settings. This suggests that extensional settings provided conditions for the circulation and deposition of metallogenic fluids. The dynamics of Cu–Au–Mo mineralization at the northern margin of the North China Craton are subduction and retreat of the Paleo–Pacific Plate, and the mode of mineralization is ‘Decratonic deposits’. Unlike the northern margin of the North China Craton, the Erguna and Xing'an blocks have a more basal and ancient lower crust, and their mineralization was not only influenced by the Okhotsk, Paleo-Asian and Paleo–Pacific plates but also related to later modifications.