黔东北大竹园萤石矿床Sm-Nd等时线年龄及其地质意义  

Sm-Nd isochron age of the Dazhuyuan fluorite deposit in northeastern Guizhou and its geological significance

作　　者：张遵遵[1] 龚银杰[1] 金世超[1] 漆双林 甘金木[1] 张利国[1] ZHANG Zun-zun;GONG Yin-jie;JIN Shi-chao;QI Shuang-lin;GAN Jin-mu;ZHANG Li-guo(Wuhan Center of China Geological Survey,CGS,Wuhan 430205,China;Central South Institute of Metallurgical Geology,Yichang 443003,China)

机构地区：[1]中国地质调查局武汉地质调查中心,湖北武汉430205 [2]中南冶金地质研究所,湖北宜昌443003

出　　处：《岩石矿物学杂志》2018年第6期949-958,共10页Acta Petrologica et Mineralogica

基　　金：中国地质调查局地质矿产调查项目(DD20179232;DD20160029)~~

摘　　要：黔东北(沿河)-渝东南(酉阳)一带广泛发育萤石、重晶石及铅锌(汞)矿化,关于其成矿时代,一直缺少直接的同位素年龄证据。黔东北大竹园萤石矿床位于上扬子地块东南缘,矿体赋存于下奥陶统桐梓组和红花园组碳酸盐岩内,受NW向断裂控制,是本区热液脉型萤石矿床的代表。本文以该矿床为研究对象,利用单矿物Sm-Nd等时线方法进行了成矿年龄测定,获得萤石Sm-Nd等时线年龄为436±15 Ma(MSWD=0. 85),萤石与共生方解石Sm-Nd等时线年龄为430±13 Ma(MSWD=1. 02),两者在误差范围内一致,表明矿床形成于加里东期,该年龄与湘西-黔东MVT铅锌矿床成矿时代(477～410 Ma)一致。本区萤石-重晶石矿床与区内产出的主要铅锌(汞)矿床关系密切,推测它们有相近的物质来源,是在同一构造运动时期形成的一个有亲缘关系的成矿系列。研究结果指示加里东期是区内重要的萤石-重晶石-铅锌(汞)中低温热液成矿期。Fluorite, barite and lead-zinc （mercury） minerals are widely distributed in northeastern Guizhou （Yan- he） -southeastern Chongqing （Youyang） area; nevertheless, there has been no direct isotope age evidence about the mineralization age. The Dazhuyuan fluorite deposit in the northeast of Guizhou is located at the southeast edge of the upper Yangtze block, the orebodies are hosted in the Lower Ordovician carbonate of Tongzi and Honghuayuan formations, controlled by NW-trending faults, and the deposit is the representative in the hydrothermal vein type fluorite deposits of this area. Therefore, the authors selected the deposit to carry out the dating of the mineralization by using the monomineral Sm-Nd isochron method and obtained the Sm-Nd isochron age of fluorite of 436 ±15 Ma （MSWD =0.85）, and the age of associated calcite and fluorite assemblage of 430 ±13 Ma （MSWD = 1.02） ; the two ages are consistent, indicating that the Dazhuyuan fluorite deposit was formed in Caledonian, and the ages are consistent with the ages （477 ± 410 Ma） of the MVT lead and zinc deposits in west Hunan-east Guizhou area. The fluorite-barite deposits in this area are closely related to the main lead-zinc （mercury） deposits, and therefore the authors infer that they had the similar sources, and constituted a metallogenic series which had genetic relationship and were formed during the same tectonic movement period. All this indicates that Caledonian period was an impor-tant medium-low temperature hydrothermal metallogenic period for the formation of fluorite-barite and lead-zinc （mercury） deposits.

关 键 词：萤石矿 SM-ND同位素 大竹园 黔东北 

分 类 号：P619.215[天文地球—矿床学] P597.3[天文地球—地质学]