The control of deformation partitioning on gold mineralization in the Qingchengzi district, Liaodong Peninsula, northeastern China

The Qingchengzi Au-polymetallic district is one of the three major gold districts in the Liaodong gold metallogenic province, northeastern China. The mid-crustal deformation partitioning in northeastern China during Early Triassic is well documented, but the corresponding deformation partitioning at the shallow crust is poorly constrained. Kinematic and chronological analyses in this study indicate that the gold mineralization in Qingchengzi was associated with reactivation of ore-related faults in different orientations during Early-Middle Triassic. The reactivation of ore-related faults is generated by an overall top-to-the-north thrusting due to the oblique convergence between the North China Craton (NCC) and South China Block (SCB). This thrusting was partitioned into the EW-striking Baiyun thrust fault, NW-striking Jianshanzi fault, NE-striking Erdaogou fault, and intralayer fractures corresponding to the pre-existing Paleoproterozoic structures and highly contrasting lithological and rheological layers. Compression structures (Baiyun and Jianshanzi faults, and intralayer fractures) controlled the distribution of altered-rock type ores that were formed in a relatively closed hydrothermal system owing to fluid mixing and carbonaceous reduction. Comparatively, quartz-vein type gold mineralization is distributed in the NE-striking faults due to depressurization and vapor loss in a relatively open hydrothermal system. This study demonstrates that the gold mineralization in the Qingchengzi Au-polymetallic district recorded the deformation partitioning at the shallow crust along the oblique convergence orogen between the NCC and SCB in Early Triassic.