投稿时间：2024-07-31
修订日期：2024-11-01
网络发布日期：2025-01-07
中文摘要:文章对柴北缘沙柳泉1号绿柱石型伟晶岩脉按结构分带开展系统矿物学和流体包裹体研究，探讨沙柳泉伟晶岩岩浆分异和成矿流体演化特征。微斜长石和云母的成分变化趋势表明，沙柳泉1号伟晶岩从边缘向核部的岩浆演化主要受分离结晶的控制，分异程度逐渐升高。熔体的演化伴随着流体盐度的降低，流体于绿柱石结晶阶段变为富CO2弱酸性流体。成矿流体从早期的中高温（200~427℃）、低盐度（w(NaCleq)为3.2%~9.9%）的NaCl-H2O体系向后期的NaCl-H2O和NaCl-H2O-（CO2）组成的2种不同性质的流体演化。大量CO2流体包裹体及流体包裹体内含较多菱铁矿（FeCO3），指示富CO2（CO32-）流体可能促进了绿柱石结晶。1号脉伟晶岩铍矿化是伟晶岩熔（流）体分异演化的结果。
Abstract:In this contribution, systematic mineralogical and fluid inclusion study were performed on the Shaliuquan No.1 beryl-type pegmatite dike at northern margin of Qaidam Basin based on its internal zonation to explore the magmatic differentiation and evolution of ore-forming fluid within the pegmatite. The evolutionary trends of microcline and mica compositions suggest that the evolution of magmatic differentiation of the No.1 pegmatite from margin to core is mainly controlled by fractional crystallization, and the degree of differentiation increases gradually. The differentiation of the pegmatite-forming melt is accompanied by the decrease in the fluid salinity. The ore-forming fluids evolved to CO2-bearing, weakly acidic fluids during the beryl crystallization. The ore-forming fluid hosed by quartz belongs to the NaCl-H2O system with medium-high temperature (200~427℃) and low salinity (w(NaCleq) 3.2%~9.9%), whereas that hosted by beryl belongs to the NaCl-H2O-(CO2) system with medium-high temperature (213~363℃) and low salinity (w(NaCleq) 1.1%~10.2%). The early-stage NaCl-H2O fluid evolved to two distinctly different fluids, namely a NaCl-H2O fluid and a NaCl-H2O-CO2 fluid at the late stage. The presence of abundant CO2-rich fluid inclusions and daughter minerals including siderite (FeCO3) indicates that the crystallization of beryl was facilitated by fluids enriched in CO2 (CO32-). The Be mineralization hosted by the Shaliuquan No. 1 pegmatite is likely the consequence of both melt differentiation and fluid evolution.
文章编号：
中图分类号：
文献标志码：
基金项目:本文得到国家重点研发计划“战略性矿产资源开发利用”专项“我国西部伟晶岩型锂等稀有金属成矿规律与勘查技术”项目（编号：2021YFC2901902）和中国地质调查局“中国矿产地质志”项目（编号：DD20221695）共同资助
引用文本：
李兴辉,凤永刚,梁婷,李善平,李积清,余福承,高景刚,刘艳荣,郑炜.2024.柴北缘沙柳泉稀有金属伟晶岩矿物学及成矿流体特征[J].矿床地质,43(6):1404~1427LI XingHui,FENG YongGang,LIANG Ting,LI ShanPing,LI JiQing,YU FuCheng,GAO JingGang,LIU YanRong,ZHENG Wei.2024.Mineralogy and ore-forming fluid characteristics of Shaliuquan rare metal pegmatites at northern margin of Qaidam Basin[J].Mineral Deposits43(6):1404~1427
图/表
