Gold mineralization in the northern margin of the North China Craton: Influence of alkaline magmatism and regional tectonic during Middle Paleozoic-Mesozoic

Abstract The northern margin of North China Craton (NNCC) has undergone multiple tectonic and magmatic episodes associated with numerous gold mineralization during Devonian to Cretaceous. The origin of gold mineralization is a subject of debate in the NNCC, but there is a consensus on a metamorphic-hydrothermal origin and a magmatic-hydrothermal origin. For this study, we focused on four gold districts including the Daqingshan, Zhangjiakou, West Liaoning, and Changbaishan from west to east. We specifically constrain the link between the Hadamengou, Dongping, Jinchanggouliang, Erdaogou and Haigou gold deposits and their magmatic episodes. The Dahuabei and Haigou granites, and Dongping syenite rocks have an alkaline affinity. In contrast, the Xitaizi-Jinchanggouliang and Xiaoxigou granites as well as the Duimiangou quartz monzonites are calc-alkaline with high alkaline rocks. They are predominantly metaluminous and high fractionated I-type granites, except the Xiaoxigou granite which is A-type granites with peraluminous nature. This indicates a variable mixing between depleted mantle-derived mafic magma and ancient crust derived magma. The magmatic events overlap the gold mineralization episodes in the NNCC. We have identified four magmatic episodes during Middle Paleozoic to Mesozoic at 400-320 Ma, 245-221 Ma, 199-161 Ma, and 143-125 Ma. On the other hand, gold mineralization was emplaced from Carboniferous to Cretaceous (390-110 Ma) with a peak in the Middle Jurassic (170-160 Ma). The available sulfur, oxygen, and carbon isotopic data from the studied NNCC gold deposits suggest that the ore-forming fluids were derived from a mixture of magmatic fluids and meteoric waters that flow in the wall rocks, except for the Hadamengou and Jinchanggouliang gold deposits. Both late deposits present a multi-source involving organic matter and other regional crustal rocks as shown by their positive δ34S values (0.6-18.5 ‰). The intrusive rocks and sulfides in the NNCC display similar lead isotope data, suggesting that the lead isotopes might have similar origin. The gold-forming materials resulting from the mixing of these fluids are the product of several alkaline magmatism activities in this region. Hence, this study has proved that gold mineralization is spatially and temporally related to the alkaline magmatism in the NNCC. The dominant tectonic events in the NNCC are marked by post-collisional or anorogenic geodynamical setting which is characterized by high alkaline features and Andean-type arc related to subduction geodynamical setting and characterized by calc-alkaline features of the studied rocks. Both tectonic events are controlled by: (1) the collision between the NCC and the Bainaimiao arc, (2) the subduction of the Paleo-Asian-ocean plate beneath the NCC, (3) the collision between the Siberian Craton and the NCC, and (4) the subduction of the western Paleo-Pacific beneath the NCC. These tectonic regimes are expressed by a transitional regime changing from compression to extension at western and an extensional regime at western and eastern parts of the NNCC, respectively.