东秦岭黄水庵碳酸岩型Mo-REE矿床方解石地球化学特征和氟碳铈矿U-Th-Pb年龄及其意义  

Geochemical Characteristics of Calcite and Bastnäsite U-Th-Pb Age of the Huangshui’an Carbonatite-hosted Mo-REE Deposit,Eastern Qinling

作　　者：王汉辉 唐利[1] 杨勃畅 唐吉根 张彦生 郭俊 冯嘉颖 盛渊明 WANG Hanhui;TANG Li;ANG Bochang;TANG Jigen;ZHANG Yansheng;GUO Jun;FENG Jiaying;SHENG Yuanming(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;PetroChina Changqing Oilfield Company,Xi’an 710018,Shaanxi,China;Inner Mongolia Nonferrous Geology and Mining(Group)108 Co.,Ltd,Chifeng 024000,Inner Mongolia,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]长庆油田分公司,陕西西安710018 [3]内蒙古有色地质矿业(集团)一〇八有限责任公司,内蒙古赤峰024000

出　　处：《西北地质》2023年第1期48-62,共15页Northwestern Geology

基　　金：教育部拔尖青年教师创新能力培养项目“豫西祁雨沟斑岩型和爆破角砾岩型金矿成矿作用研究”(2652019047)资助成果。

摘　　要：黄水庵矿床位于华北克拉通南缘熊耳山矿集区,是东秦岭钼矿带典型的碳酸岩型Mo-REE矿床之一。黄水庵矿床的Mo-REE矿体主要产于碳酸岩中,碳酸岩呈脉状和隐爆角砾岩体侵入太华群。笔者通过碳酸岩方解石微量元素、C-O同位素以及氟碳铈矿U-Th-Pb年龄的研究,探讨了碳酸岩岩浆的来源、成岩成矿年龄和构造地质背景,对东秦岭地区的构造演化和成矿作用提供约束。方解石的微量元素具有富集大离子亲石元素、亏损高场强元素的特征,稀土配分模式为轻稀土元素富集的右倾型(LREE/HREE=3.08~10.33)。方解石δ13 CV-PDB值为−4.11‰~−5.62‰、δ18OV-SMOW值为6.40‰~7.62‰,指示初始火成碳酸岩特征。氟碳铈矿U-Th-Pb定年的加权平均年龄为(213.5±2.9)Ma,代表了黄水庵REE矿化的时限。综合已有成岩成矿年龄和同位素研究结果,认为黄水庵矿床的成矿时代为晚三叠世,形成于秦岭造山带碰撞后的伸展背景。富Mo下地壳与富集地幔的部分熔融形成碳酸岩岩浆,其中地壳物质的再循环是形成碳酸岩型Mo-REE矿化的关键因素之一。The Huangshui’an deposit,located in Xiong’ershan ore concentration area in the southern margin of the North China Craton,is one of the typical carbonatite-hosted Mo-REE deposit in the East Qinling Mo metal-logenic belts.The Mo-REE ore bodies of the Huangshui’an deposit mainly are hosted in carbonatite which occur as veins and cryptoexplosive breccia intrusions in the Taihua Group.Based on the study of trace elements and C-O isotopic compostion of calcite,and bastnäsite U-Th-Pb dating,we discuss the origin of carbonatite,metallogenic age and tectonic setting,which provide constraints for tectonic evolution and mineralization in the East Qinling belt.The trace elements of calcite are characterized by enrichment of large ion lithophile elements and depletion of high field strength elements,and are enriched in LREE(LREE/HREE=3.08~10.33).Theδ13 CV-PDB values of calcite ranging from−4.11‰to−5.62‰andδ18 OV-SMOW values ranging from 6.40‰to 7.62‰indicate the characteristics of primary mantle-derived carbonatite.The weighted average age of U-Th-Pb dat-ing of bastnäsite is 213.5±2.9 Ma,representing the age of REE mineralization in the Huangshui'an deposit.Based on diagenetic and metallogenic age and available isotopic ages,we propose that the metallogenic age of the Huangshui’an deposit is Late Triassic.The Huangshui’an carbonatite-hosted deposit was formed in the post-collisional setting of the Qinling orogenic belt.The partial melting of Mo-fertile lower crust and enriched mantle formed the carbonatite magma,and the recycling of crustal material is one of the key factors for the for-mation of carbonatite-hosted Mo-REE mineralization.

关 键 词：碳酸岩 方解石微量元素 碳氧同位素 氟碳铈矿U-Th-Pb定年 黄水庵矿床 

分 类 号：P618[天文地球—矿床学] P597[天文地球—地质学]