东昆仑大格勒地区富铌橄榄岩中的含铌矿物组成  

Niobium-bearing mineral compositions of niobium-rich peridotites in the Dagele area of the East Kunlun Mountains

作　　者：李五福 王强[1,2] 李玉龙[3] 王秉璋 金婷婷[3] 刘建栋[3] 王涛[3] 张新远[3] 郑英[3] 袁博武[3] 韩晓龙[3] 周金胜 王泰山[3] 王春涛 曹锦山[3] 赵忠国[3] LI Wufu;WANG Qiang;LI Yulong;WANG Bingzhang;JIN Tingting;LIU Jiandong;WANG Tao;ZHANG Xinyuan;ZHEN Ying;YUAN Bowu;HAN Xiaolong;ZHOU Jinsheng;WANG Taishan;WANG Chuntao;CAO Jinshan;ZHAO Zhongguo(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of the Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources,Qinghai Geological Survey Institute,Xining 810012,Qinghai,China)

机构地区：[1]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]青海省地质调查院青藏高原北部地质过程与矿产资源重点实验室,青海西宁810012

出　　处：《地球化学》2024年第5期708-718,共11页Geochimica

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0702);青海省地质矿产勘查开发局项目(青地矿科[2021]61号);青海省地质调查局项目(2021074055kc024)联合资助。

摘　　要：铌(Nb)是我国极度紧缺的战略性矿产资源,对外依存度非常高。近期本研究团队在东昆仑大格勒地区发现了志留纪–泥盆纪碱性岩–碳酸岩型铌、磷矿化杂岩体,岩石类型主要为橄榄岩、单斜辉石岩、橄榄辉长岩、角闪石岩和碳酸岩等。橄榄岩中Nb_(2)O_(5)品位为0.5%~0.8%,平均为0.6%,是原始地幔Nb丰度(0.713×10^(-6))的数千倍,显示了Nb元素的超常富集。本文在光学显微镜岩相学研究的基础上,应用电子探针背散射图像、能谱分析及电子探针定量分析技术,对橄榄岩中含铌矿物类型、共生关系及其化学组成进行研究。结果表明,橄榄岩中含铌矿物主要为烧绿石、(铈)铌钙矿、(铈)钙钛铌矿、褐铈铌矿和含铌钛铁矿,其中烧绿石含量最高(约1%)。5种矿物中Nb_(2)O_(5)含量依次为:烧绿石(71.45%~74.50%)、(铈)铌钙矿(50.96%~55.26%)、(铈)钙钛铌矿(43.27%~47.73%)、褐铈铌矿(41.63%~44.26%)以及含铌钛铁矿(4.63%~4.99%)。烧绿石呈半自形粒状晶,充填于磁铁矿等矿物粒间。本研究为东昆仑造山带碱性–碳酸岩型铌矿成矿潜力分析、成矿规律总结以及下一步矿产勘查部署提供了依据。Niobium(Nb)is an extremely scarce strategic mineral resource in China,and its dependence on foreign countries has exceeded 99%in recent years.Recently,we discovered a Silurian-Devonian alkaline rock-carbonate-type Nb and phosphate mineralized complex in the Dagele area of East Kunlun.The rock types are mainly peridotite,clinopyroxenite,olivine gabbro,hornblende rock,and carbonate.The Nb_(2)O_(5)grade in the peridotite ranges from 0.5%to 0.8%,with an average of 0.6%,which is thousands of times higher than the primary mantle Nb abundance(0.713´10−6),indicating an extraordinary enrichment of Nb.The types,paragenesis,and chemical compositions of Nb-rich minerals in the peridotite are studied using electron microprobe backscatter images,energy spectrum analyses,and electron microprobe quantitative analyses based on optical microscopy petrography.The results show that the main Nb-rich minerals in the peridotite are pyrochlore,cerium niobium,(cerium)calcium niobite,(cerium)perovskite niobium ore,and Nb-bearing ilmenite.Among these minerals,pyrochlore had the highest Nb content(up to 1%).The Nb_(2)O_(5)contents in the five minerals were as follows:pyrochlorite(71.45%-74.50%),cerium niobium(50.96%-55.26%),(cerium)calcium niobite(43.27%-47.73%),(cerium)perovskite niobium ore(41.63%-44.26%),and Nb-bearing ilmenite(4.63%-4.99%).Pyrochlore is mainly composed of subhedral fine-grained crystals filled between mineral grains such as magnetite.This study provides a basis for the analysis of the metallogenic potential of alkaline-carbonate niobium ore in the East Kunlun orogenic belt and provides a summary of metallogeny and the next step of mineral exploration and deployment.

关 键 词：东昆仑 大格勒 橄榄岩 含铌矿物 电子探针 

分 类 号：P616[天文地球—矿床学]