Early Cretaceous magma flare-up and its implications on gold mineralization in the Jiaodong Peninsula, China

The gold deposits of the Jiaodong Peninsula in the eastern part of the North China Craton constitute one of the richest gold reserves in the world and also define a unique class of gold mineralization. Previous studies correlated the gold mineralization in Jiaodong to Mesozoic magmatic intrusives, particularly granitoids derived from mixed sources of reworked Paleoproterozoic basement rocks, or Early Cretaceous dykes. Here we evaluate the geochemical characteristics of the major magmatic suites in the region as well as the timings of the magma pulses with respect to that of gold metallogeny. It is revealed that the peak of gold mineralization at ca. 120–125 Ma coincides with the major volcanic activity in Jiaodong as represented by the extrusion of basaltic trachyandesites. The magma flare-up was accompanied by a transient fluid influx through an enriched and metasomatised mantle with gold and sulfur predominantly scavenged from subducted sediments over the downgoing paleo-Pacific Plate. The remarkable structural control of the gold-bearing quartz veins and the proximity of the larger gold deposits in Jiaodong to the major Tan–Lu Fault clearly indicate that fluids channeled along structural pathways were the major contributor to the gold mineralization in the area. The asthenospheric upwelling and decompression melting triggered extensive magmatism and crustal recycling aided by the development of deep extensional fractures possibly associated with major stress field changes during plate re-orientation in the Early Cretaceous.