Late Mesozoic magmatism and gold metallogeny of the Jiaodong Peninsula, China: A response to the destruction of the North China Craton

Abstract

The late Mesozoic destruction of the eastern North China Craton (NCC) resulted from intense crust-mantle interaction, culminating in the formation of world-class gold deposits in the Jiaodong Peninsula at ca. 120 Ma. We present zircon U-Pb geochronological data, Hf isotopic compositions, whole-rock major and trace element, and Sr-Nd-Pb isotopic compositions for two suites of granitoids: one (the Linglong suite) that hosts significant mineralization and the other (the Weideshan suite) that is largely unmineralized. The Linglong suite was emplaced in the Late Jurassic at 160 ± 3 Ma to 155 ± 3 Ma, whereas the Weideshan suite was emplaced in the Early Cretaceous at 121 ± 2 Ma to 118 ± 1 Ma, coeval with gold mineralization. Geochemical data indicate the Linglong suite was derived from the melting of thickened lower crust of the NCC, mixed with material from the Yangtze Craton (YC) and intervening Su-Lu Orogenic Belt, whereas the Weideshan suite was formed from the partial melting of lower continental crust, with the addition of enriched lithospheric mantle components. The Late Jurassic magmatism was associated with crustal growth resulting from the continental collision between the NCC and YC and subsequent subduction of the Paleo-Pacific Oceanic Plate (PPOP). In contrast, Early Cretaceous magmatism was triggered by rapid lithospheric thinning and asthenospheric upwelling resulting from slab roll-back and stagnation of the PPOP beneath the NCC. Lithospheric delamination induced the widespread development of secondary structures associated with the major Tan-Lu Fault, providing favorable loci for the accumulation of auriferous fluids.