山东金城地区焦家断裂带下盘隐伏花岗岩类岩石地球化学特征及锆石U-Pb年龄

胶西北金矿集区内中生代花岗岩类分布广泛，与区内金矿成矿关系密切。焦家断裂带深部下盘隐伏的岩体岩性以花岗岩类为主，其成岩时间及成因分类尚存在争议，本次在金城地区采取深部花岗岩类样品，开展了锆石U-Pb测年、主微量元素等测试工作，对花岗岩的岩相学特征、形成时间、岩石地球化学特征等进行了研究。金城地区焦家断裂带下盘深部花岗岩类为中生代侏罗纪玲珑型花岗岩（测得锆石U-Pb年龄值为158.4Ma和160.4Ma）和白垩纪郭家岭型花岗岩。本次研究花岗岩样品均表现为I型花岗岩的地球化学特征，说明玲珑型花岗岩重熔物质较复杂，若重熔地壳源岩为火成岩表现为I型花岗岩的特征，重熔的地壳源岩为表壳岩类，则表现为S型花岗岩的特征。区内中生代花岗岩类的形成与太平洋板块俯冲华北板块有关，属大陆弧花岗岩类，为火山弧构造环境。

Geochemical Characteristics and Zircon U-Pb Age of Concealed Granitoids in the Footwall of Jiaojia Fault Zone in Jincheng Area, Shandong Province

Mesozoic granitoids are widely distributed in the gold concentration area of Northwest Jiaodong, which is closely related to gold mineralization in the area. The lithology of the concealed rock mass in the deep footwall of Jiaojia fault zone is mainly granitoids, and there are disputes about its diagenetic time and genetic classification. This time, deep granite samples were taken in Jincheng area, zircon U-Pb dating, major and trace elements and other tests were carried out, and the petrographic characteristics, formation time and petrochemical characteristics of granite were studied. The deep granitoids in the footwall of Jiaojia fault zone in Jincheng area are Mesozoic Jurassic Linglong type granite (the measured zircon U-Pb ages are 158.4ma and 160.4ma) and Cretaceous Guojialing type granite. The granite samples in this study show the geochemical characteristics of I-type granite, indicating that the remelting materials of Linglong type granite are complex. The remelted crustal source rock is igneous rock, which shows the characteristics of I-type granite. If the remelted crustal source rock is surface crust rock, it shows the characteristics of S-type granite. The formation of Mesozoic Granitoids in the area is related to the subduction of the Pacific Plate to the North China Plate. They belong to continental arc granitoids and belong to the volcanic arc tectonic environment.