吉林省塔东群锆石U-Pb定年、微量元素研究及其地质意义

发布时间：2018-07-02 14:28

本文选题：塔东群 + 岩浆锆石　；参考：《地球科学》2017年04期

【摘要】：吉林省塔东群以含大型磁铁矿床而著称,塔东铁矿是吉黑成矿省内最大的火山喷流沉积-变质改造型铁矿.由于塔东群地质特征复杂,多种地质作用复合叠加,使其形成时代归属一直存在争议.通过LA-ICP-MS锆石定年,确定了吉林省塔东群黑云斜长片麻岩和磁铁透辉斜长变粒岩中锆石年代.黑云斜长片麻岩中锆石呈长柱状,Th/U值为0.17~0.65,206Pb/238U加权平均年龄为517.6±2.7Ma,代表了其原岩火山岩形成的年龄.磁铁透辉斜长变粒岩中共有两组锆石年龄,其中一组短柱状,Th/U值介于0.78~1.00,加权平均年龄为249.8±4.0Ma,代表后期热事件年龄;另一组锆石半自形短柱状晶形,异常高的U、Th,Th最高含量可达17 422μg/g,~(206)Pb/~(238)U加权平均年龄为518.3±3.8Ma,表示热液活动年龄,显示该区518.3Ma左右经历了一次热液作用,可能与该区的岩浆作用以及塔东铁矿的成矿有关.据此,塔东群内塔东铁矿可能存在一期早寒武世(±520Ma)的成矿作用.
[Abstract]:The Tadong Group of Jilin Province is famous for its large magnetite deposits. Tadong Iron Mine is the largest volcanic jet deposition-metamorphic iron ore deposit in Jihei metallogenic province. Due to the complex geological characteristics of the Tadong Group and the complex superposition of various geological processes, the origin of the Tadong Group has always been controversial. Based on the LA-ICP-MS zircon dating, the zircon ages of the Black-Yun plagioclase gneiss and the magnetite permeable feldspar granulite in the Tadong Group, Jilin Province, were determined. The weighted mean age of zircon in the biocline gneiss is 517.6 卤2.7 Ma, which represents the age of volcanic formation of its original rocks. The U / U value of zircon is 0.170.65206Pb / 238U, and the average weighted age is 517.6 卤2.7Ma. There are two groups of zircon ages in magnetite perpendicular amphiphilic granulites, one of which is short columnar Th / U value between 0.78 and 1.00, the weighted average age is 249.8 卤4.0 Ma, which represents the later thermal event age, and the other group of zircon semiautomorphic short columnar crystals. The maximum Th content of the abnormal high UH is 17 422 渭 g / g ~ (206) Pb / 238 U weighted mean age is 518.3 卤3.8 Ma. it indicates that the hydrothermal activity age in this area is about 518.3 Ma, which may be related to magmatism and mineralization of Tadong Iron Mine. Based on this, it is suggested that the first stage of early Cambrian (卤520 Ma) mineralization may exist in the Neitadong Iron Mine of the Tadong Group.
【作者单位】：吉林大学地球科学学院;哈尔滨师范大学地理科学学院;桂林理工大学地球科学学院;
【基金】：中国地质调查局项目(No.1212011120329)
【分类号】：P597.3;P618.31

【相似文献】