赣北阳储岭斑岩型钨钼矿床成矿岩体副矿物U-Pb年龄精确厘定  

Accessory minerals U-Pb geochronology of monzogranitic porphyry in Yangchuling porphyry W-Mo deposit in northern of Jiangxi Province, South China

作　　者：范楚涵 倪培[1] 王国光[1] 张凯涵 王广琳 李文生 崔健铭 贺佳峰 FAN ChuHan;NI Pei;WANG GuoGuang;ZHANG KaiHan;WANG GuangLin;LI WenSheng;CUI JianMing;HE JiaFeng(State Key Laboratory for Mineral Deposits Research,Institute of Geo-Fluids,School of Earth Science and Engineering,Frontiers Science Center for Critical Earth Material Cycling,Nanjing University,Nanjing,210023,Jiangsu,China)

机构地区：[1]南京大学内生金属矿床成矿机制研究国家重点实验室地质流体研究所,地球科学与工程学院,关键地球物质循环前沿科学中心,江苏南京210023

出　　处：《矿床地质》2022年第1期35-52,共18页Mineral Deposits

基　　金：国家自然科学基金委重点项目(编号:41830426);中央高校基本科研业务费专项资金资助(编号:020614380122);关键地球物质循环前沿科学中心科研基金(编号:JBGS21031)联合资助。

摘　　要：赣北阳储岭大型斑岩型钨钼矿床地处江南造山带东部九岭-障公山隆起带,是江南钨矿带典型的斑岩型白钨矿矿床。钨钼矿体主要发育于二长花岗斑岩内,少量发育于花岗闪长岩和爆破角砾岩中。矿体以脉状、网脉状、似层状、透镜状、星点状产出。前人针对阳储岭矿床已开展全岩Rb-Sr法、全岩K-Ar法、锆石U-Pb法、辉钼矿Re-Os法等诸多定年工作,但因"过剩Ar"的存在、后期热事件扰动和高U花岗岩中锆石发生蜕晶化等原因,导致成岩年龄结果及解释仍存在争议。文章选取与成矿相关的二长花岗斑岩开展了独居石和金红石原位LA-ICPMS U-Pb同位素定年分析,以精确厘定成矿岩体的侵位年龄。研究表明,独居石年龄为(146.06±0.61)Ma(MSWD=10.2),金红石年龄为(150.20±2.60)Ma(MSWD=1.13)。此外,独居石是开展高U成钨岩体定年的有力对象,独居石年龄与前人发表的高精度辉钼矿Re-Os年龄在误差范围内相一致,独居石年龄可更准确地代表矿床的成矿岩体年龄。阳储岭矿床所处的江南钨矿带内的矿床形成时代主要可分为中侏罗世(约162 Ma)、晚侏罗世(150~135 Ma)和早白垩世(135~125 Ma)3个阶段。其中,阳储岭钨钼矿床属区内第二成矿阶段,该阶段古太平洋板块俯冲角度变缓,江南钨矿带处于弧后环境。The Yangchuling large porphyry tungsten-molybdenum deposit is located in the Jiuling-Zhanggongshan uplift zone of the eastern part of the Jiangnan orogenic belt. It is a typical porphyry type scheelite deposit in the Jiangnan tungsten belt. Scheelite and molybdenite ore bodies are mainly developed in monzogranite porphyry,and a small amount is developed in granodiorite and explosive breccia. The ore body occurs in vein, veinlets,stratoid, lenticular and star point shape. Previous geochronological studies have been carried out for the Yangchuling deposit, such as whole rock Rb-Sr method, whole rock K-Ar method, zircon U-Pb method, molybdenite Re-Os method and so on. However, due to the existence of "excess Ar", the disturbance of late thermal events and the metamictization of zircons in high U granites, the age results and interpretation of rock-forming ages are still controversial. In this study, the in situ LA-ICP-MS U-Pb isotopic analysis was performed on monazite and rutile in monzogranite porphyries associated with W-Mo mineralization, so as to accurately determine the emplacement age of the ore-forming granites. The age of monazite is(146.06±0.61)Ma(MSWD=10.2) and the age of rutile is(150.20±2.60)Ma(MSWD=1.13). In addition, monazite is a powerful dating object for the high U intrusive rocks with tungsten mineralization,and the monazite age is consistent with the molybdenite age of high precision Re-Os dating within the error range published previously, the monazite age can more accurately represent the age of ore-forming intrusions of the deposit. The mineralization ages of the deposits in the Jiangnan tungsten belt can be divided into three stages: Middle Jurassic(about 162 Ma), Late Jurassic(150~135 Ma) and Early Cretaceous(135~125 Ma). The Yangchuling W-Mo deposit is in the second mineralization stage, during which the subduction angle of the ancient Pacific Plate slows down, and jiangnan tungsten deposit is in a back-arc environment.

关 键 词：地球化学 斑岩型钨钼矿床 独居石 金红石 LA-ICP-MS U-Pb同位素定年 阳储岭 赣北 

分 类 号：P618.65[天文地球—矿床学] P618.67[天文地球—地质学]