赣中紫云山花岗岩晶质铀矿的电子探针U-Th-Pb化学定年

发布时间：2018-03-24 15:50

本文选题：晶质铀矿　切入点：铀源矿物　出处：《地球科学》2017年03期

【摘要】：紫云山岩体是赣中地区与钨铀成矿关系极为密切的过铝质花岗岩体,但目前该岩体的成岩时代尚不明确.通过偏光显微镜、扫描电镜、电子探针等手段,首次开展了紫云山花岗岩中赋存晶质铀矿的精细矿物学研究.结果表明:晶质铀矿主要赋存于黑云母之中,少数被黄铁矿包裹,部分晶质铀矿被不同程度溶蚀和交代,表明晶质铀矿是本区花岗岩型铀矿的主要铀源矿物之一.利用电子探针U-Th-Pb化学定年法测得蕉坑单元(J3J)5颗晶质铀矿年龄为154.5~168.9Ma,加权平均年龄为161.8±2.4Ma(MSWD=0.26,n=26),庙前单元(J3M)三颗晶质铀矿年龄为152.8~164.7 Ma,加权平均年龄为159.7±3.2 Ma(MSWD=0.2,n=15).获得的年龄与南岭地区主要含钨花岗岩的侵入时间高度一致,对应华南中生代大规模岩浆活动的第二阶段.晶质铀矿年龄与华南含钨花岗岩锆石U-Pb年龄非常一致,验证了过铝质富铀花岗岩中晶质铀矿电子探针定年方法的可行性.
[Abstract]:Ziyunshan rock body is a peraluminous granitic body closely related to tungsten and uranium mineralization in central Jiangxi, but its diagenetic age is not clear at present. By means of polarizing microscope, scanning electron microscope, electron probe and so on, Fine mineralogical studies of the crystalline uranium deposits in Ziyunshan granite have been carried out for the first time. The results show that the crystalline uranium deposits mainly occur in biotite, a few are wrapped in pyrite, and some of the crystalline uranium deposits are dissolved and replaced to varying degrees. It is indicated that the crystalline uranium deposit is one of the main uranium source minerals of granitic type uranium deposits in this area. The age of 5 crystalline uranium deposits in the Jiaokeng unit J 3J is 154.5 卤168.9 Ma.The weighted average age is 161.8 卤2.4 Ma, MSWDU 0.26n26n26and Miaoqian unit J3M). The uranium age is 152.8U 164.7 Ma, and the weighted average age is 159.7 卤3.2MaM MSWDU 0.2N ~ 150.The obtained age is consistent with the intrusive time of the major tungsten-bearing granites in Nanling area. It corresponds to the second stage of Mesozoic large-scale magmatism in South China. The age of uraniferous uranium deposit is very consistent with the zircon U-Pb age of tungsten bearing granites in South China, which verifies the feasibility of electron probe dating method for uranium-rich granites in peraluminous granites.
【作者单位】：东华理工大学放射性地质与勘探技术国防重点学科实验室;江西有色地质勘查局;
【基金】：国家自然科学基金项目(No.41302053) 东华理工大学博士启动资金(No.DHBK201120)
【分类号】：P619.14;P597.3

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