Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第27卷    第11期    总第224期    2017年11月

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文章编号:1004-0609(2017)-11-2329-11
湘西花垣铅锌矿田方解石REE元素和Sr同位素地球化学
隗含涛1, 2,邵拥军1, 2,叶 周3,熊伊曲1, 2,周皓迪1, 2,谢友良1, 2

(1. 中南大学 有色金属成矿预测与地质环境监测教育部重点实验室,长沙 410083; 2. 中南大学 地球科学与信息物理学院,长沙 410083; 3. 湖南省地质博物馆,长沙 410004)

摘 要: 湘西花垣铅锌矿田随着杨家寨、大脑坡及清水塘等一系列大型–超大型铅锌矿床的发现,已经成为世界千万吨级铅锌矿田。通过矿脉切穿关系和不同的矿物共生组合,将花垣矿田成矿过程分为3个阶段。对矿田内主成矿期方解石的REE及Sr同位素进行了研究,并与含矿围岩及不同时代地层的REE和Sr同位素进行了对比。结果表明:方解石稀土元素特征与地层具有相似性,其中I阶段方解石REE含量较低,ΣREE为1.73×10-6~10.94×10-6,平均为4.77×10-6;LREE/HREE为6.21~10.19,平均为7.96;87Sr/86Sr比值0.70935~0.71001,平均为0.709643。II阶段方解石REE含量比I阶段高,ΣREE为24.53×10-6~67.88×10-6,平均为46.71×10-6;LREE/HREE为6.21~10.19,平均为7.96;87Sr/86Sr比值为0.70923~0.70944,平均为0.709301,比I阶段的低,说明I、II阶段成矿流体存在差异。结合围岩及不同时代地层地球化学特征认为,I阶段成矿流体主要为含矿层建造水,混有深循环热卤水;II阶段成矿流体主要为深循环热卤水,混有大气降水,从I阶段至II阶段成矿流体还原性增强。

 

关键字: 方解石;稀土元素;锶同位素;成矿流体;花垣铅锌矿田

REE and Sr isotope geochemistry of gangue calcites from Huayuan Pb-Zn orefield in western Hunan, China
WEI Han-tao1, 2, SHAO Yong-jun1, 2, YE Zhou3, XIONG Yi-qu1, 2, ZHOU Hao-di1, 2, XIE You-liang1, 2

1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, Changsha 410083, China; 2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China; 3. The Geological Museum of Hunan, Changsha 410004, China

Abstract:With the discovery of the large to super large Yangjiazhai, Danaopo and Qingshuitang Pb-Zn deposits, the Huayuan orefield becomes a world-class super large Pb-Zn orefield. According to the crosscutting relationship of ore veins and coexisting mineral assemblage, the mineralization process was subdivided into three stages. REE and strontium isotope of calcites were analyzed and compared with those of ore-hosting limestone and strata of different geological times. The results show that the REE patterns of calcites are similar to those of strata. Stage I calcites display low total contents of REE (ΣREE=1.73×10-6-10.94×10-6,average 4.77×10-6), 87Sr/86Sr ratios ranging from 0.70935 to 0.71001 (average 0.709643) and LREE/HREE ratios range from 6.21 to 10.19 (average 7.96). Stage II calcites display higher contents of REE (ΣREE=24.53×10-6-67.88×10-6,average 46.71×10-6) and lower 87Sr/86Sr ratios ranging from 0.70923 to 0.70944 (average 0.709301) than those of stage I calcite, and similar LREE/HREE ratios range from 6.21 to 10.19 (average 7.96). These indicate that the ore-forming fluids of stages I and II are derived from different origins. According to geochemical characteristics of wall rock and strata of different geological times, it is concluded that the ore-forming fluids of stage I are mainly connate water in ore-hosting strata, mixed by deep-source circular brine; the ore-forming fluids of stage II are mainly deep-source circular brine, mixed by meteoric water, and the reducibility increases from stage I to II.

 

Key words: calcite; REE; Sr isotope; ore-forming fluids; Huayuan Pb-Zn orefield

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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