摘要
广西大化县透闪石玉矿床产自贫镁碳酸盐岩中,是一种新型透闪石玉矿床,其成矿物质来源及成因研究较为薄弱。对该矿床中围岩、蚀变岩、侵入岩和透闪石玉进行主微量元素和锶同位素对比研究,结果表明:透闪石玉的微量元素和稀土元素配分模式与石灰岩和大理岩相似,且微量元素和稀土元素含量与大理岩相关性较强(相关系数0.931),说明Ca的来源与大理岩有关;透闪石玉^(87)Sr/^(86)Sr与1000/Sr呈线性负相关关系,说明透闪石玉^(87)Sr/^(86)Sr(0.7070)主要受大理岩(0.7075)和辉绿岩(0.7061)两个端元控制,外推1000/Sr=0得到的^(87)Sr/^(86)Sr值与辉绿岩一致,说明成矿流体为岩浆热液;透闪石玉Y/Ho值(均值49.10)高于大理岩和辉绿岩(均值分别为44.53、24.30),说明其受岩浆热液作用较强烈。结合大化透闪石玉成矿特点,推测其成矿物质Ca来自大理岩,Si和Mg来自辉绿岩。采用稀土元素配分、δCe、δEu、Zr/Hf、Nb/Ta、Sr/Ba、U/Th、W、V、Cu等指标判断,其氧逸度较高,成矿环境为碱性。广西大化透闪石玉矿床的成矿过程分为4个阶段:基性岩浆侵入→石灰岩变质为大理岩→富含Mg和Si的基性岩浆热液形成→热液交代大理岩形成透闪石玉。
Turbidite jade deposit in Dahua,Guangxi,produced in the poor magnesium carbonate rock stratum,is a new type of turbidite jade deposit.The source of its mineralization material and the cause of the study is relatively weak.This study has carried out a comparative study by testing the main trace elements and strontium isotopes of peripheral rocks,altered rocks,intrusive rocks and tremolite jade in the deposits.The results show that the trace element and rare earth element partitioning patterns tremolite jade are similar to those of limestone and marble,the trace element and rare earth element contents correlate well with marble(correlation coefficient 0.931),suggesting that the source of Ca is related to marble.There is a linear negative correlation between ^(87)Sr/^(86)Sr and 1000/Sr in Dahua stratified tremolite jade,indicating that ^(87)Sr/^(86)Sr(0.7070)is controlled by marble(0.7075)and diabase(0.7061)endmembers.The ^(87)Sr/^(86)Sr value obtained by extrapolating 1000/Sr=0 is consistent with the ^(87)Sr/^(86)Sr value in the gabbro,suggesting that the mineralising fluid is magmatic hydrothermal;the values of Y/Ho in Dahua stratified tremolite jade(avg.,49.10)are higher than those in marble and diabase(avg.,44.53 and 24.30,respectively),indicating that the marble is more strongly affected by magmatic-hydrothermal action.Combined with the characteristics of Dahua tremolite jade,it is inferred that Ca comes from marble,Mg and Si come from diabase.Using rare earth element composition,δCe,δEu,Zr/Hf,Nb/Ta,Sr/Ba,U/Th,W,V,Cu and other indicators,it determines that their mineralization environment is alkaline with high oxygen fugacity.The formation of tremolite jade deposits in Dahua,Guangxi,is divided into four stages:basic magmatic intrusion→limestone metamorphism to marble→formation of Mg-and Si-rich basaltic magmatic hydrothermal fluids→hydrothermal fluid accounted for the formation of tremolite jade from marble.
作者
陆俐合
于海燕
蓝叶
阮青锋
沙鑫
易泽邦
LU Lihe;YU Haiyan;LAN Ye;RUAN Qingfeng;SHA Xin;YI Zebang(College of Earth Sciences,Guilin University of Technology,Guilin 541006,China;Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541006,China;Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources in Guangxi,Guilin University of Technology,Guilin 541006,China;Testing Center for Gold and Jewelry of Jiangsu Province,Nanjing 210002,China)
出处
《桂林理工大学学报》
CAS
北大核心
2024年第3期391-401,共11页
Journal of Guilin University of Technology
基金
广西自然科学基金项目(2020GXNSFAA159167)
广西科技基地和人才专项项目(2019AC20007)。
关键词
透闪石玉
地球化学
锶同位素
成矿物质来源
大化
广西
tremolite jade
geochemistry
strontium isotope
ore-forming material source
Dahua
Guangxi
