西天山阔拉萨依铁矿火山岩地球化学特征及其地质矿产意义  

Geochemical Characteristics of Volcanic Rocks in Kuolasayi Iron Deposit,Western Tianshan and Its Geological and Metallogenic Significance

作　　者：高永伟[1,2] 王志华[1,2] 张振亮[1,2] 李忠煜[1] 董福辰[1] 谭文娟[1,2] 姜寒冰[1,2] Gao Yongwei Wang Zhihua Zhang Zhenliang Li Zhongyu Dong Fuchen Tan Wenjuan Jiang Hanbing(Xi＇an Center of Geological Survey, CGS, Xi＇an 710054,China MLR Key Laboratory of Genisis and Exploration of Magmatic Ore Deposits, Xi＇an 710054,China)

机构地区：[1]中国地质调查局西安地质调查中心,西安710054 [2]国土资源部岩浆作用成矿与找矿重点实验室,西安710054

出　　处：《地质科技情报》2017年第4期10-18,共9页Geological Science and Technology Information

基　　金：国家自然科学基金项目(41602096;41402079);国土资源部公益性行业科研专项课题(201211073-02);中国地质调查局地质调查项目(12120115022401);陕西省科技资源共享平台项目(2013FWPT-02)

摘　　要：阔拉萨依铁矿大地构造位于西天山造山带西段伊犁-中天山板块南缘,矿体赋存于石炭系大哈拉军山组火山岩系内。对火山岩开展了系统的岩石学和地球化学研究。结果表明,火山岩属高钾钙碱性-钙碱性系列,富集轻稀土元素(LREE)和大离子亲石元素(LILE),亏损高场强元素(HFSE,如Nb、Ta、Ti),具有活动大陆边缘火山岩的地球化学特征。不同火山岩的地球化学特征类似,为同源岩浆演化的产物。岩浆源区为经过俯冲带流体改造后的富集地幔楔,且有俯冲板片沉积物参与其部分熔融过程,岩浆在上升过程中受到了地壳物质的同化混染作用,并且发生了结晶分异作用。根据岩石组合和地球化学特征,推断阔拉萨依铁矿火山岩形成于南天山洋向伊犁-中天山板块俯冲的活动大陆边缘环境。结合前人研究成果和矿床地质特征,认为阔拉萨依铁矿是火山作用的产物,具有火山岩型铁矿床的特征。Kuolasayi iron deposit is tectonically located at the southern part of Yili-Central Tianshan Plate in the Western Tianshan Organic Belt.The iron bodies are mainly hosted in the volcanic rocks of Late Carboniferous Dahalajunshan Formation.This article presents the systematic study of petrography and geochemistry of this deposit.The result shows that the volcanic rocks belong to high-K calc-alkaline and calcalkaline series,with enrichment of LREE and LILE and the depletion of HFSE（such as Nb,Ta and Ti）,indicating geochemical characteristics of volcanic rocks from active continental margin.The similar geochemical features illustrate that different volcanic rocks are from the same magma source.The primary magmas were derived from enriched mantle metasomatized by the subduction fluid,which involved with partial melting of subducted sediments,and coupled with a certain degree of fractional crystallization and contamination of crustal materials during the magma ascent.The rock association and geochemical features indicate that the volcanic rocks in Kuolasayi iron deposit were generated from active continental margin during the south Tianshan oceanic basin towards the north beneath Yili-Central Tianshan Plate.Combining this study results with the previous former research achievements and geological features of the deposit,we suggest that the formation of Kuolasayi iron deposit is the product of volcanism and the deposit should be a volcanic iron deposit.

关 键 词：火山岩 地球化学 大哈拉军山组 活动大陆边缘 阔拉萨依铁矿 

分 类 号：P588.1[天文地球—岩石学]