西天山备战铁矿火山岩地球化学特征、锆石U-Pb年代学及Hf同位素组成研究  

Zircon U-Pb Geochronology and Hf Isotopes of Volcanic Rocks in Beizhan Iron Ore of the West Tianshan

作　　者：韩琼[1] 弓小平[1] 程松林[2] 张冀 宋相龙[1] 凤骏 潘展超[1] 谢磊[1] 苏虎[1] 刘学良[1] 

机构地区：[1]新疆大学地质与矿业工程学院,乌鲁木齐830049 [2]中国地质大学(北京),北京100871 [3]新疆维吾尔自治区地质学会,乌鲁木齐830000

出　　处：《地质学报》2015年第1期70-82,共13页Acta Geologica Sinica

基　　金：中国地质调查局项目"西天山阿吾拉勒成矿带铁矿成矿条件;成矿规律与勘查示范研究"(编号1212010880202);"西天山阿吾拉勒晚古生代火山作用与铁铜矿选区评价研究"(编号12120113044000);国家自然科学基金项目"新疆东准噶尔卡拉麦里金矿带成矿流体特征及其与侵入体的关系研究"(编号41462004)联合资助成果

摘　　要：备战铁矿是西天山阿吾拉勒成矿带新近发现的大型铁矿之一,矿区广泛发育下石炭统火山岩。本文对矿区火山岩进行了主量元素、微量元素、稀土元素地球化学特征分析、LA-ICP-MS锆石U-Pb测年以及锆石Lu-Hf同位素组成研究,以探讨矿区大哈拉军山组火山岩产出的构造环境、备战铁矿的成岩成矿时代和火山岩的来源。矿区火山岩主要由玄武岩、玄武安山岩、安山岩、流纹岩组成,以中基性岩为主,大多为高钾钙碱性系列;微量元素和稀土元素表明矿区火山岩产出构造环境为活动陆缘火山岛弧;锆石U-Pb测试结果显示矿区南部斜长花岗斑岩的形成时代为晚石炭世早期(301±0.93Ma),成矿时代为早石炭世晚期。结合地质背景认为该铁矿至少有两期成矿期,在成因上为火山沉积后期叠加矽卡岩化的磁铁矿矿床。锆石Lu-Hf同位素组成特征表明备战铁矿的岩石来源于元古代、太古代地壳物质的部分熔融,并且源区物质在地壳中存在较长的时间。Beizhan iron ore is one of the newly discovered medium-sized iron ores in Awulale mineralization of west Tianshan. Lower Carboniferous volcanic rocks are widely developed in the mine. This paper analyses the major elements, trace elements, REE geochemical characteristics and LA-ICP-MS zircon U-Pb dating and zircon Hf-Lu isotopes of the volcanic rocks, and discusses the tectonic environment of Dahalajunshan formation in the mine, diagenetic mineralization age and the source of the volcanic rocks, they belong to rich calc-alkalic series, and consist of basalt, basaltic andesite, andesite and liparite. They are dominated by mafic rocks. Trace elements and REE show that the tectonic environment of the volcanic rocks in the mine belongs to activities terrestrial volcanic island arc. LA-ICP-MS zircon U-Pb suggests that the formation time of granite mine in southern yield is an isotopic age of（301±0.93）Ma, which represents late Early Carboniferous, and its metallogenic epoch is early Irate Carboniferous. According to its geological background, we conclude that Beizhan iron ore has two metallogenic periods at least, In the aspect of genesis, It is a magnetite deposits which had overlaid the volcanic sedimentary superposition and skarn. Zircon Hf-Lu isotopes shows that Beizhan iron ore rocks are from the Proterozoic, partial melting of Archean crustal material, and the source material there has been in the earth＇s crust for a long time.

关 键 词：火山岩 地球化学 LA-ICP-MS锆石U-PB定年 西天山备战铁矿 LU-HF同位素 

分 类 号：P618.31[天文地球—矿床学] P597.3[天文地球—地质学] P588.14