Rapid tectonic transition, crust-mantle interaction, and gold metallogenesis in the Jiaodong Peninsula, eastern China: Revealed by Early Cretaceous granitoids and microgranular mafic enclaves

Abstract

The Early Cretaceous granitoids and mafic enclaves (MEs) are extensively distributed throughout the Jiaodong Peninsula, providing valuable insights into the region's tectono–magmatic evolution and gold mineralization processes. This contribution presents zircon geochronology, whole–rock major and trace element compositions, and Sr–Nd–Pb isotopic data for the Early Cretaceous Guojialing and Weideshan suites, as well as related magmatic enclaves in the Jiaodong Peninsula. These rocks were emplaced at approximately 128 Ma and 118 Ma, corresponding to two distinct magmatic events. Whole–rock and isotope geochemical characteristics indicate that the Early Cretaceous granitoids were formed through the interaction and mixing of lower crustal and lithospheric mantle magmas. Adakitic Shangzhuang MEs of the Guojialing suite originated from the mingling and homogenization of lower crustal felsic magma with mantle–derived basaltic magma. The mafic components of arc–like Aishan MEs of the Weideshan suite were derived from partial melting of metasomatized lithospheric mantle. The Early Cretaceous magmatism in the Jiaodong Peninsula reflects the geodynamic evolution, marking the transition from the subduction and collision of the Paleo-Pacific Oceanic Plate (PPOP) beneath the Eurasian Plate to the roll-back of the subducted PPOP slab. This transition is characterized by a shift from crustal thickening to lithospheric thinning and from a compressional setting to an extensional setting. The early Early Cretaceous magmatism marks the culmination of the crustal thickening event in the Jiaodong Peninsula. The short interval (approximately 10 Ma) between the Guojialing and Weideshan magmatic events supports the hypothesis of intensified lithospheric delamination. During this period, the intense tectonic, magmatic, and fluid activities served as the material source, migration pathways, and spatial hosts for the intense metallogenic processes in the Jiaodong Peninsula.