Structural control and genesis of gold deposits in the Liaodong Peninsula, northeastern North China Craton

Two distinct styles of gold mineralization occurred in the Liaodong Peninsula, in the northeastern North China Craton. One formed an altered rock-type gold deposit in the west, and the other formed a quartz vein-type deposit in the east. Geological investigations and structural analysis show that these deposits may have originated from two distinct tectono-magmatic hydrothermal systems. The former is an E-W-trending contractional-extensional structural system formed in the Late Triassic, which includes the deposits in Baiyun, Jianshangou, and Maoling. The latter is related to high-angle strike-slip faults formed in the Early Cretaceous, and includes the Wulong gold deposit. Stress-induced tectonic analyses show that the principal stress in the western district was nearly N-S-oriented contractional stress initially, which subsequently changed to extensional stress; this might have been the result of the collision and subsequent extension of the Siberia Craton, North China Craton, and Yangzi Craton in the Late Triassic. The principal stress in the eastern district was nearly NW-SE-oriented contractional and sinistral shear stress initially, which subsequently changed to extensional stress, which may be the result of regional extension associated with the westward subduction of the PaleoPacific Plate in the Early Cretaceous. The structural control of the gold mineralization is manifested at all scales from regional to mines to orebodies; that is, the grading of the ores was controlled by different generations or orders of deformation. Gold ores were mainly formed under brittle or brittle-shear deformation conditions; in particular with extensive ore bearing catalasite flows; which were generated by both the brittle or brittle-shear failure along major fault systems and related Late Triassic and Early Cretaceous magmatic hydrothermal activity. This genetic origin for gold mineralization and ore-bearing catalasite flows may provide support for the mechanism of flash vaporization in mineralization processes that form mesothermal gold systems.