西天山式可布台铁矿火山岩地球化学特征、成岩时代厘定及其构造意义  

Geochemical characteristics and petrogenic age of volcanic rocks in the Shikebutai iron deposit of West Tianshan Mountains

作　　者：李潇林斌 弓小平[1] 马华东 韩琼[1] 宋相龙[1] 谢磊[1] 凤骏 王建设[1] 

机构地区：[1]新疆大学地质与矿业工程学院,新疆乌鲁木齐830049 [2]新疆国家三0五项目办公室,新疆乌鲁木齐830000

出　　处：《中国地质》2014年第6期1791-1804,共14页Geology in China

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"子项目"西天山阿吾拉勒成矿带铁矿成矿条件与成矿规律研究"(资[2010]矿评01-03-26)和"西天山阿吾拉勒晚古生代火山作用与铁铜矿选区研究(12120123044000)"联合资助

摘　　要：式可布台铁矿位于西天山阿吾拉勒铁矿成矿带西段,是此矿带极具代表性的铁矿床。主要赋存于以凝灰岩为主的石炭系上统伊什基里克组火山岩中。本文通过对式可布台矿区的火山岩进行岩石地球化学和LA-ICPMS锆石U-Pb测年分析来探讨火山岩形成的构造环境与成岩时代。地球化学分析表明大多数火山岩样品显示为高钾钙碱性系列;主量元素表明矿区火山岩主要由安山岩、英安岩、流纹英安岩组成,为钙碱性系列;微量元素和稀土元素表明矿区火山岩产出的构造环境为火山岛弧;LA-ICPMS锆石U-Pb测年显示火山岩的206Pb/238U加权平均年龄分别为(301±1)Ma和(313±2)Ma,表明该区的火山岩为晚石炭世早期。结合区域地质资料,认为矿区内出露的高钾钙碱性系列火山岩可能属于俯冲过程末期大陆岛弧岩浆作用的产物,其岩石的形成与构造岛弧环境有关,主体与下石炭统大哈拉军山组火山岩岩石化学特征相似。Located in the western part of the West Tianshan Awulale iron metallogenic belt, the Shikebutai iron deposit is a representative deposit in this belt. It mainly occurs in the Carboniferous Yishijilike Formation volcanic rocks dominated by tuff. Based onj rock geochemistry and LA- ICPMS zircon U- Pb dating of volcanic rocks in the Shikebutai iron deposit, this paper discusses the tectonic environment and petrogenic age of the volcanic rocks. Geochemical analysis shows that most of the volcanic rocks vary from high potassium talc-alkaline volcanic rocks to shoshonite series in chemical composition. The major elements indicate that volcanic rocks are mainly composed of andesite, dacite, rhyolite and dacite, belonging to calc- alkaline series. Trace elements and rare earth elements indicate that the tectonic environment for the formation of the volcanic rocks was active epicontinental volcanic arc. LA-ICPMS zircon U-Pb dating shows that ^206b/^238U weighted average ages of volcanic rocks are 301±1 Ma and 313±2Ma, suggesting that volcanic rocks in this deposit were formed in early Late Carboniferous. Combined with regional geological data, the authors hold that the high- K calc- alkaline volcanic rocks of shoshonite series in the ore district may be the product of the late subduction of continental arc magmatism, and the tectonic environment for the formation of the volcanic rocks was active epicontinental arc. The chemical characteristics of the volcanic rocks are on the whole similar to features of Lower Carboniferous Dahalajtmshan Formation volcanic rocks.

关 键 词：LA-ICPMS 地球化学 伊什基里克组 式可布台铁矿 西天山 

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