Petrogenesis of the Early Cretaceous Zhouguan Granodiorite in Jiaodong Peninsula: Evidence from Mineralogy, Geochemistry, Geochronology, and Sr-Nd Isotopes

The Jiaodong Peninsula is the most important gold mineralization area in China, and formation of deposits closely related to granitoids. isotopic ages Early Cretaceous granodiorites northwestern are concentrated range 111~123 Ma, coeval with area. However, studies on geotectonic settings granodiorites, especially their petrogenesis relationship Peninsula, scarce. Based field petrographic observations, geochemistry, EPMA analysis, zircon U-Pb chronology, Sr-Nd isotopes Zhouguan granodiorite area, age determined as 115 Ma ± 0.77 Ma; analysis shows that biotite mainly composed Fe-biotite Mg-biotite, its MgO content ranging from 9.797% 11.635%. crystallization temperature 500 °C~625 °C emplacement depth rock mass 3.98~8.71 km. amphibole includes magnesiohornblende, pargasite, magnesiosadanagaite; among them, former two crustal origin, while magnesiosadanagaite mantle origin. pressure 0.75~3.02 kbar 2.81~11.4 km, respectively, for latter 4.64 17.53 respectively. (87Sr/86Sr) values 0.710424 0.711074 (143Nd/144Nd) 0.511530 0.511808. parental magma highly oxidized high-water favorable Au enrichment. Combined Nb-Y Yb-Ta diagrams, a model describing proposed.