江西冷水坑火山-侵入杂岩LA-ICP-MS锆石U-Pb年龄及地质意义  

The Discovery of Late Jurassic Volcanic Rocks in Lengshuikeng,Jiangxi and Their Geological Significance

作　　者：余明刚[1,2] 赵希林[2] 钱迈平[2] 段政[2] 张雪辉[2] 万浩章[3] 肖茂章[3] 孙建东[2] 

机构地区：[1]南京大学地球科学系,江苏南京210093 [2]南京地质矿产研究所,江苏南京210016 [3]江西省地质矿产勘查开发局九一二大队,江西鹰潭335001

出　　处：《岩矿测试》2015年第1期138-149,共12页Rock and Mineral Analysis

基　　金：中国地质调查局地质调查工作项目(12120113065200;1212011121099;12120113070800)

摘　　要：江西冷水坑矿田是武夷山地区重要的银铅锌矿集中区之一,以斑岩型矿床和火山沉积-热液改造型矿床为特色,前人对冷水坑矿床的成岩成矿作用、控矿构造、成矿模式等开展了大量的研究,但对不同地质体与成矿的先后关系、岩浆活动期次与成矿作用的关系研究相对薄弱。本文对打鼓顶组火山岩和含矿花岗斑岩进行了激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）锆石U-Pb年代学研究,结果表明打鼓顶组底板、顶板晶屑凝灰岩形成时代分别为161.3±1.3 Ma、160.75±0.96 Ma,含矿花岗斑岩形成时代为168.09±0.80 Ma,结合以往研究资料,将冷水坑矿田火山-侵入岩岩浆活动划分为3个期次：第Ⅰ期火山-侵入岩浆活动形成于164~170 Ma;第Ⅱ期火山-侵入岩浆活动发生于157~161 Ma,为火山沉积-热液改造型矿床和斑岩型矿体的主要成矿时代,岩浆活动和成矿时代基本一致;第Ⅲ期火山-侵入岩浆活动时限为140~146 Ma。也暗示华南冷水坑等地晚侏罗世火山岩形成于华南中生代构造体制转换的关键时期,为华南晚中生代构造背景的研究提供了重要地质依据。The Jiangxi Lengshuikeng ore field,characterized as porphyry deposits and volcanic sedimentary hydrothermal reworking deposits,is one of the major Ag-Pb-Zn ore concentration areas in Wuyi Mountain area.There has been much research carried out on mineralization,the metallogenic model,and ore-controlling structure of the Lengshuikeng deposit.However,it is still unclear about the relationship of different geological bodies with mineralization and magmatism.In this paper,a description of a zircon LA-ICP-MS U-Pb geochronology approach and its implementation on the volcanic rock of Daguding Formation and ore-bearing granite porphyry is given.The crystal tuffs from the top and bottom of Daguding Formation and ore bearing granite porphyry yield U-Pb age of161.3 ± 1.3 Ma,160.75 ± 0.96 Ma and 168.09 ± 0.80 Ma,respectively.These results indicate that there were three stages of volcano-magmatic activities in the Lengshuikeng ore field with ages of 164- 170 Ma,157- 161 Ma,and 140- 146 Ma,respectively.The 157- 161 Ma is the main metallogenic epoch of the volcanic sedimentaryhydrothermal reworking type deposit and porphyry type deposit.The discovery of the late Jurassic volcanic rocks in Lengshuikeng provides the important geological evidence for the detailed study of the Mesozoic tectonic regime transition in South China.

关 键 词：打鼓顶组 含矿花岗斑岩 激光剥蚀电感耦合等离子体质谱(LA-ICP-MS) 锆石U-Pb定年 构造转换 江西冷水坑 

分 类 号：O657.63[理学—分析化学] P588.121[理学—化学]