黔西南望谟县打岩萤石矿床流体包裹体地球化学特征  

Geochemical Characteristics of Fluid Inclusions in the Dayan Fluorite Deposit in Wangmo County of Southwestern Guizhou Province

作　　者：杨友[1] 公斌[1] 潘有良 肖玉 YANG You;GONG Bin;PAN Youiang;XIAO Yu(Guizhou Provincial Bureau of Geology and Mineral Exploration and Development 117 Geological Brigade,Guiyang,Guizhou 550018;College of Earth Science,Chengdu University of Technology,Chengdu,Sichuan 610059)

机构地区：[1]贵州省地质矿产勘查开发局117地质大队,贵州贵阳550018 [2]成都理工大学地球科学学院,四川成都610059

出　　处：《地质与勘探》2024年第5期971-981,共11页Geology and Exploration

基　　金：贵州省2022年度新一轮找矿突破行动项目(编号:黔自然资〔2022〕632号)资助。

摘　　要：黔西南望谟县打岩萤石矿床产于二叠系吴家坪组灰岩层间破碎带及P/T界面构造蚀变体中。通过萤石流体包裹体岩相学、显微激光拉曼光谱成分分析,探讨打岩独立萤石矿成矿流体性质、来源及成因机制,以丰富望谟县地区萤石矿研究资料,为下一步找矿勘查提供参考。该矿床流体包裹体主要发育气液H_(2)O包裹体(Ⅱ型)及少量富子晶包裹体,萤石流体包裹体均一温度为101~216℃,主要集中在130~150℃;盐度为0.17%~1.45%NaCl_(eqv),密度为0.84~0.96 g/cm^(3),属低盐度及低密度流体范围。成矿流体成分较为简单,固相成分为方解石(CaCO_(3))、气相成分主要为H_(2)O、微弱CO_(2),液相成分为H_(2)O,主要为NaCl-H_(2)O体系。打岩萤石矿床为金、锑矿成矿流体同源,属于该流体晚期阶段成矿产物。含F成矿流体沿南盘江深大断裂上涌通过P/T界面运移,与围岩发生水岩反应萃取围岩中的钙,在向地表运移中因大气降水加入使成矿流体发生冷却,同时构造扩容减压作用使成矿流体沸腾导致CaF2沉淀。在吴家坪组灰岩层间破碎带、节理裂隙及P/T界面虚脱空间等成矿有利部位形成交代充填型低温热液萤石矿床。The Dayan fluorite deposit in Wangmo County of southwestern Guizhou Province is located in the fractured zone between the Permian Wujiaping Formation limestone and the P/T interface structural alteration body.Through the analysis of fluorite fluid inclusion lithology and micro laser Raman spectroscopy composition,the properties,sources,and genesis mechanisms of independent fluorite ore fluids were explored,to enrich the research data on fluorite deposits in Wangmo County and provide reference for the next step of mineral exploration.Fluid inclusions mainly develop gasliquid H_(2)O inclusions(type II)and a small amount of rich crystal inclusions.The homogenization temperature of fluorite fluid inclusions is 101~116℃,mainly concentrated in 130~150℃.The salinity is 0.17%to 1.45%NaCleqv,and the density is 0.84 to 0.96 g/cm^(3),belonging to low salinity and low density.The composition of the ore-forming fluid is relatively simple,with the solid phase consisting of calcite(CaCO_(3)),the gas phase mainly consisting of H_(2)O and weak CO_(2),and the liquid phase consisting of H_(2)O,mainly the NaCl-H_(2)O system.The fluorite in the Dayan deposit belongs to the same source of ore-forming fluids with gold and antimony deposits,and is a late-stage ore-forming product of this fluid.The ore-forming fluid containing F surged up along the Nanpanjiang deep fault and migrated through the P/T interface,which has undergone water rock reactions with the surrounding rock to extract calcium from the rock.During its migration to the surface,the ore-forming fluid cooled due to the addition of atmospheric precipitation,while the tectonic expansion and decompression caused ore-forming fluid to boil,resulting in fluorite precipitation.A low-temperature hydrothermal fluorite deposit of metasomatic filling type was formed in favorable mineralization areas such as fractured zones,joint fissures,and P/T interface voids between the Wujiaping Formation limestone layers.

关 键 词：萤石矿 流体包裹体 均一温度 打岩背斜 望谟 黔西南 

分 类 号：P595[天文地球—地球化学] P619.215[天文地球—地质学]