Abstract
The Jiaodong gold province, within the eastern margin of the North China block and the translated northeastern edge of the South China block, has a stated premining gold resource exceeding 4,500 metric tons (t). It is thus one of the world’s largest gold provinces, with a present cumulative annual production estimated at 60 t Au. More than 90% of the Jiaodong gold resource is hosted by batholiths and related bodies of the Linglong (ca. 160–145 Ma) and, to a lesser degree, Guojialing (ca. 130–122 Ma) suites. The intrusions were emplaced into high-grade metamorphic basement rocks of the Precambrian Jiaobei (North China block) and Sulu (South China block) terranes during a 70-m.y.-period of lithospheric delamination, extensional core complex formation, and exhumation. The deposits are located about 20 to 200 km to the east of the continental-scale NNE-striking Tancheng-Lujiang (Tan-Lu) strike-slip fault system. They occur along a series of more regional NNE- to NE-striking brittle and ductile-brittle faults, which appear to intersect the Tan-Lu main structure to the southwest. This system of early to middle Mesozoic regional thrust faults, reactivated during Cretaceous normal motion and ore formation, tends to occur along the margins of the main Linglong batholiths or between intrusions of the two suites of granitoids. Orebodies are mainly present as quartz-pyrite veins (Linglong-type) and as stockwork veinlets and disseminated mineralization (Jiaojia-type). The two mineralization styles are transitional and may be present within the same gold deposit. The ca. 120 Ma timing of gold mineralization correlates with major changes in plate kinematics in the Pacific Basin and the onset of seismicity along the Tan-Lu fault system, with the enormous fluid volumes and associated metal being derived from sediment devolatilization above the westerly subducting Izanagi slab.
Morphology and features of Cambrian oncoids and responses to palaeogeography of the North China Platform
