湖北省通城—九宫山地区九宫山花岗岩锆石U-Pb定年及地质意义

Zircon U-Pb Dating and Its Geological Significance of Jiugongshan Granite in Tongcheng-Jiugongshan Area,Hubei Province

通城—九宫地区九宫山花岗岩体是其附近已发现的钨矿体的主要来源。在研究钨矿物质来源过程中,利用地球化学方法分析了花岗岩体的地球化学特征,采用LA-ICP-MA锆石U-Pb定年方法测定了花岗岩体的形成时代。同时确定了九宫山花岗岩的构造背景环境,探讨了其物质来源及与成矿之间的关系。通过岩石地球化学试验表明,该岩体为地壳中以火山岩为源区重熔形成的“S”型花岗岩。综合研究表明该型花岗岩岩石测年结果为(124.6±1.7)Ma,代表岩浆结晶年龄,属于中生代白垩纪时期;岩体为燕山早期岩浆活动的产物,产于大陆碰撞构造环境。

The main source of tungsten ore bodies found nearby is Jiugongshan granite rock mass in Tongcheng-Jiugong Mountain Area.During the study process of material source of tungsten ores,the geochemical characteristics of granite rock mass is studied based on geochemical methods,the formation age of granite rock mass is determined by LA-ICP-MA zircon U-Pb dating.At the same time,the tectonic background environment of Jiugongshan granite was determined,and its material source and its relationship with mineralization were discussed.Rock geochemical test results show that the rock mass is an"S"type granite formed by remelting volcanic rocks in the crust.The comprehensive study results show that the dating result of the granite rock is about(124.6±1.7)Ma,which represents the age of magma crystallization and belongs to the Mesozoic Cretaceous period;the rock mass is the product of magmatic activity in the early Yanshanian,it should be produced in the continental collisional tectonic setting.