西北地质2024，Vol.57Issue(4)：50-65,16.DOI:10.12401/j.nwg.2024049
内蒙古喀喇沁旗大西沟萤石矿床成因:来自稀土元素、流体包裹体和H-O同位素的制约
Genesis of the Daxigou Fluorite Deposit,Harqin Banner,Inner Mongolia,China:Constraints from Rare Earth Elements,Fluid Inclusions and H-O Isotopes
摘要
Abstract
Fluorite is a strategic mineral that plays an important role in maintaining national resource security and stable economic development.The Harqin Banner in Inner Mongolia is located at the northern margin of the North China Craton,which is an important production area for fluorite ore.In this study,rare earth element(REE),fluid inclusion and H-O isotope analyses of the Daxigou fluorite deposit of the Harqin Banner were car-ried out to investigate the nature of its ore-forming fluids and the genesis of the deposit.The rare earth element content of the early-stage fluorite in Daxigou is higher than the late-stage fluorite,and the Y/Ho ratios of the ear-ly and late-stage fluorspar are similar,indicating that the mineralizing fluids are homologous.In the Tb/La-Tb/Ca diagram,all the samples fall within the range of hydrothermal deposits,indicating that the deposits are hydrothermal in origin.The early-and late-stage fluorites exhibit negative Eu anomalies and weak negative Ce anomalies,indicative of their formation in a reducing environment.The fluid inclusions trapped in fluorite are dominated by liquid-rich gas‒liquid two-phase inclusions,with the homogeneous temperatures concentrated at 160～190℃,the salinities ranging from 0.18%to 2.57%NaCleqv,the densities concentrated at 0.88～0.94 g/cm3.The H-O isotope data from regional fluorite deposits indicated that the H-O isotope compositions of the independent fluorites show a significant latitudinal effect,which suggests the ore-forming fluids were domi-nated by meteoric precipitation.The fluorspar deposit in Daxigou is a medium-low temperature hydrothermal vein type deposit.According to the crosscutting relationships,it is inferred that the Daxigou fluorite deposit formed during the late Yanshan period(<120 Ma),a large number of faults and fissures formed by ductile tec-tonic deformation during the two phases of the Late Jurassic and the Early Cretaceous provided a channel for the transport and aggregation of ore-forming fluids,and the fluid-rock interactions were the main reason for fluorite precipitation.关键词
萤石矿床/稀土元素/流体包裹体/H-O同位素/热液脉型/华北陆块北缘Key words
fluorite deposit/rare earth elements/fluid inclusions/H-O isotopes/hydrothermal vein type/the northern margin of the North China Craton分类
天文与地球科学引用本文复制引用
马少兵,裴秋明,王亮,韩术合,梁翼,孙清飞,沈家乐..内蒙古喀喇沁旗大西沟萤石矿床成因:来自稀土元素、流体包裹体和H-O同位素的制约[J].西北地质,2024,57(4):50-65,16.基金项目
国家自然科学基金项目(42302104),陕西省自然科学基础研究计划(2024JC-YBQN-0259)联合资助. （42302104）
