西北地质2024，Vol.57Issue(4)：1-20,20.DOI:10.12401/j.nwg.2024038
阿尔金西段库木塔什萤石矿床成因:磷灰石U-Pb年龄、原位Sr-Nd同位素、地球化学约束
Genesis of Kumutashi Fluorite Deposit in the West Altyn-Tagh Orogen,NW China:Constraints from Apatite In-Situ U-Pb Dating,Sr-Nd Isotope and Chemistry
摘要
Abstract
In recent years,significant breakthroughs in fluorite prospecting have been made in the western Al-tyn-Tagh Terrane,and Kaerqiaer,Kumutashi and other deposits have been discovered successively,however,the research on metallogenic epoch and ore-forming processes are still unclear.In this paper,the closely symbi-otic apatite with fluorite were selected as the research object to carry out the main microanalysis of apatite,U-Pb dating and in situ Sr-Nd isotopic test analysis,so as to explore the metallogenic epoch and the genesis of deposit.The apatite often has a self-semi-automorphic structure with uniform surface and nearly transparent under monopolarized light,mainly symbiotic with fluorite,calcite,tainiolite,bastnaesite and other minerals.The study shows that the U-Pb isotope age of apatite microregion is(448±27)Ma,and the fluorite mineralization is close-ly related to the invasive activity of alkali feldspar granite,all of which are the products of the late Ordovician tectonic-magmatic activity.The F content of apatite is 4.20%to 5.12%;the Cl content is less than 0.02%,and the very low Cl content indicates a low dissolved fluid Cl content.The content of rare earth elements is high(908×10-6～2 164×10-6),and the partition curve of rare earth shows strong Eu negative anomaly and positive Ce negative anomaly.This anomaly is obviously consistent with its associated fluorite,calcite and alkali feldspar granite,which may be closely related to the dissolution of massive fluid in the magma-hydrothermal stage.The ratio of 87Sr/86Sr of apatite is from 0.709 13 to 0.710 47,the ratio of 143Nd/144Nd is from 0.511 38 to 0.511 53,and εNd(t)is from-13.27 to-10.26,reflecting that the ore-forming materials have the characteristics of crust-man-tle mixing.Comprehensive studies show that the ore-forming age of fluorite in the western Altyn-Tagh Terrane is Ordovician,closely related to the same period alkali feldspar granite,formed in the post-collision extension stage,the ore-forming fluid may be derived from the melt-fluid evolution of alkali feldspar granite,and it is a magmatic hydrothermal filling type deposit.关键词
地球化学特征/磷灰石/萤石矿床/库木塔什/阿尔金西段Key words
geochemical characteristics/apatite/fluorite deposit/the Kumutashi deposit/West Altyn-Tagh Orogen分类
天文与地球科学引用本文复制引用
高永宝,刘基,陈康,王亮,赵辛敏,李艳广,刘明,张龙,王元伟,张毅..阿尔金西段库木塔什萤石矿床成因:磷灰石U-Pb年龄、原位Sr-Nd同位素、地球化学约束[J].西北地质,2024,57(4):1-20,20.基金项目
陕西省自然科学基础研究计划项目"阿尔金卡尔恰尔超大型萤石矿带高氟岩浆-热液演化与成矿机制研究"(2023-JC-YB-241),中国地质调查局自然资源综合调查指挥中心科技创新基金项目"阿尔金卡尔恰尔地区超大型萤石成矿带成矿流体性质研究"(KC20230011),中国地质调查局项目"西昆仑大红柳滩-甜水海地区大型矿产资源基地综合调查"(DD20190143)、"新疆若羌县帕夏拉依档一带萤石、锂矿产调查评价"(DD20243309)、"阿尔金伊里奇曼-红柳沟地区萤石、金铜矿产调查评价"(DD20211551)联合资助. （2023-JC-YB-241）
