沉积与特提斯地质2024，Vol.44Issue(4)：697-709,13.DOI:10.19826/j.cnki.1009-3850.2024.06002
西藏拿若斑岩型铜(金)矿床黄铁矿、黄铜矿原位硫同位素特征及其地质意义
In-situ sulfur isotope characteristics of pyrite and chalcopyrite from the Naruo porphyry Cu(Au)deposit in Xizang:Implications for geological significance
摘要
Abstract
The Naruo deposit is the third largest porphyry Cu(Au)deposit within the Duolong ore district in Xizang.Previous studies have extensively investigated the petrogenesis,metallogenetic geological chronology,and metallogenic geological background.However,the ore-forming mechanism,including the source of sulfur,remains unclear.This study focuses on the widespread occurrence of pyrite and chalcopyrite in the Naruo ore deposit.Through methods such as optical microscopy identification and LA-MC-ICP-MS isotopic analysis,mineralogical characteristics and isotopic geochemistry were investigated.The aim is to elucidate the in-situ sulfur isotope characteristics,reveal the ore genesis of the deposit,and provide guidance for mineral exploration.Based on microscopic observations,three types of pyrite are categorized,from earlier to later:Py-Ⅰ→Py-Ⅲ→Py-Ⅱ→Py-Ⅲ.Except for Py-Ⅰ,all others are closely associated with the occurrence of chalcopyrite.Pyrite exhibits δ34S values ranging from-4.05‰ to 3.49‰(with a mean of-0.2 ‰,n=53),while chalcopyrite demonstrates smaller δ34S values,ranging from-7.24‰ to 0.32‰(with a mean of-2.44‰,n=24).These test results closely approximate values found in other deposits within the ore cluster.The total sulfur value of the ore-forming fluid(δ34SΣ)is-3.06‰,indicating that the source of sulfur is primarily associated with magmatic sulfur.The sulfur isotope mineral pairs of pyrite-chalcopyrite indicate ore-forming temperatures ranging from 255℃to 590℃,with a central ore-forming temperature of 320℃,revealing a mesothermal ore-forming environment in the ore deposit center.The spatial distribution patterns of sulfur isotopes indicate a gradual decrease in δ34S values from the mineralization center to the periphery,which is notably different from some alkaline porphyry-type deposits.This study suggests that such variation is attributed mainly to ore formation in a mesothermal environment and the degassing of remote SO2,thus serving as crucial exploration indicators for the Naruo deposit.This study has enriched our understanding of the sources of sulfur and ore-forming temperatures,among other ore-forming mechanisms,in the Naruo ore deposit.It lays the foundation for further research in ore-forming theories and mineral exploration.关键词
黄铁矿/黄铜矿/原位硫同位素/拿若矿床/多龙矿集区/西藏Key words
pyrite/chalcopyrite/in-situ S isotope/Naruo deposit/Duolong ore district/Xizang分类
天文与地球科学引用本文复制引用
李发桥,旦增宗追,郭朵朵,李彦波,李建力,唐菊兴,王立强,宋扬,李社,林彬,李海峰,杨欢欢,孙豪..西藏拿若斑岩型铜(金)矿床黄铁矿、黄铜矿原位硫同位素特征及其地质意义[J].沉积与特提斯地质,2024,44(4):697-709,13.基金项目
国家重点研发计划项目"西藏铜多金属资源基地绿色勘查与增储示范"(2022YFC2905001) （2022YFC2905001）
中国地质科学院矿产基本科研业务费项目"西藏重要成矿带斑岩铜金矿资源基地深部勘查示范"(JKYZD202316) （JKYZD202316）
国家自然科学基金面上项目"斑岩-高硫型浅成低温热液铜金成矿系统的砂金矿物学标志—以西藏多龙矿集区为例"(42172100) （42172100）
中国地质调查局地质调查项目"铜(金)锑等紧缺战略性矿产调查与潜力评价"(DD20230054),"青藏高原关键地段综合探测与找矿预测"(DD20240078) （金）
