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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.
The Tadong Group in Jilin Province is well known for its large magnetite deposits, which is the largest volcanic sedimentary-metamorphic iron ore deposit in the Kathei metallogenic province. Due to the complex geologic features of the Tadong Group and the complex geological features Superimposed to make it belong to the formation of the era has been controversial.Through the LA-ICP-MS zircon dating, to determine the Jilin Tadong group of biotite plagioclase gneiss and magnetite diopside granite zircon zircon age black The zircons in the plagioclase gneiss have long columnar shape with Th / U values of 0.17-0.65 and 206Pb / 238U weighted average ages of 517.6 ± 2.7Ma, representing the age of the original volcanic rocks. There are two groups of zircon ages in the granitic rocks. One group of short columns has Th / U values ranging from 0.78 to 1.00 and a weighted average age of 249.8 ± 4.0Ma, representing the age of late thermal events. The highest content of U, Th and Th in the columnar crystals was 17 422 μg / g and the weighted average age of 206 Pb / 238 U was 518.3 ± 3.8 Ma, indicating the age of hydrothermal activity, indicating that 518.3 Ma experienced a hydrothermal fluid that may be related to the magmatism in the area and the mineralization of the Tadong iron mine, Mineralization in a period of Early Cambrian (± 520Ma).