Study On The Characteristics Of Zircon Of Early Cretaceous Granite In The Jiaodong Area And Its Restriction On Gold Mineralization

The Jiaodong gold mine concentration area not only has a large scale of mineralization,but also its metallogenic geological background,producing environment and metallogenic role are unique in the global gold metallogenic model.Previous studies have shown that its mineralization is closely related to Mesozoic granite,especially the Early Cretaceous granite is very important for the gold mineralization in Jiaodong area.In this paper,we systematically sampled granites of the Early Cretaceous in the Jiaoxibei area ? Qixia area and Wendeng area.Detailed mineralogy,petrology,geochemistry and chronology were studied by means of microscope,ion probe,laser densification multi-receiver plasma mass spectrometer and laser Raman analysis instruments.Through the analysis of rare earth and trace elements,Lu-Hf and O isotopes of zircon,the nature?degree of differentiation and oxygen fugacity characteristics of the granitic magma were compared.Furthermore,the magma evolution and provenance properties were analyzed to with a view to restricting the possible causes of the huge gold accumulation in the Jiaoxibei area.The study found that there are obvious differences between the early stage of Early Cretaceous granite in the Jiaoxibei area?the Daliuhang and Xiangkuang of the Qixia area and the Early Cretaceous later period granite in the Wendeng area.The specific performance is as follows:the early stage of Early Cretaceous Guojialing-type granitic magma in the Jiaoxibei area is a crust-mantle mixture.Its provenance is mainly the ancient Archean crust components.The magma oxygen fugacity and the degree of differentiation are the highest in the study area.The early stage of Early Cretaceous granitic magma in the Qixia area is also a crust-mantle mixture.Its provenance is mainly Neoarchean-Paleoproterozoic crustal components.The magma oxygen fugacity performance is second highest,and the degree of differentiation is relatively low.The Early Cretaceous later period granitic magma in the Wendeng area is also a crust-mantle mixture.Its provenance is also dominated by Paleoproterozoic crustal components.The oxygen fugacity is the lowest,and the degree of magma differentiation is between the first two.The proven gold resource reserves in Jiaodong gold mine concentration area are about 5000 tons.Mainly distributed in the Jiaoxibei area(80%).The research in this paper shows that the main factors causing this huge difference are related to the provenance properties,degree of differentiation and oxygen fugacity of the Early Cretaceous granitic magma of ore-forming geological body.Specifically,the Guojialing-type granitic magma in the Jiaoxibei area is mostly ancient Archean crust-derived material,and the highest magma oxygen fugacity and degree of differentiation may be the main reasons for the huge gold accumulation in this area.