湖南东坡矿田金船塘锡铋矿床铅同位素地球化学及成矿年龄

Lead Isotope Geochemistry and Ore-forming Age of Jinchuantang Sn-Bi Deposit in Dongpo Ore Field, Hunan Province

文章选取金船塘锡铋矿床中的辉铋矿_黄铁矿矿石及长石样品进行了铅同位素分析 ,并对其中两个放射成因铅含量较高的黄铁矿进行了单矿物分步酸淋滤铅同位素分析。结果表明矿床的Pb_Pb等时线成矿年龄为(16 4± 12 )Ma,该年龄与千里山岩体燕山早期第一期的岩浆侵入年龄在误差范围内相同 ,说明矿化的发生与该期花岗岩的侵入关系非常密切。金船塘矿床铅同位素的构造演化模式研究表明铅来源于上地壳 。

This paper presents lead isotope analytical results of bismuthine and pyrite from sulfide ores and feldspar from Qianlishan granite in the large-size Jinchuantang Sn-Bi deposit, Dongpo ore field, Hunan Province. Two pyrite samples with high radiogenic Pb were subjected to the Pb-stepwise leaching experiment. The Pb isotopic data form an excellent isochron with age of (164±12) Ma, similar to the first phase intrusive age of the early Qianlishan Yanshanian granite. It is held that this age represents the mineralization age, and that the formation of the deposit was related to the granitic magmatism. The lead of the Jinchuantang Sn-Bi deposit was derived most likely from upper crust materials as deduced from the Zartman Pb model. This conclusion is also consistent with the origin of the Qianlishan granite, an S-type granite body formed by partial melting of the upper crust.