中文摘要：

西天山备战铁矿赋存于以玄武岩、玄武质凝灰岩、安山质凝灰岩、安山岩和英安岩为主的晚石炭世火山岩中,属于高钾钙碱性系列。本文通过对矿区火山岩进行岩石地球化学分析探讨火山岩形成的构造环境。地球化学分析表明,火山岩表现为轻稀土（LREE）相对于重稀土（HREE）富集的配分形式,具有＂左陡右缓＂的特征;相对富集大离子亲石元素（LILE）Ba、Rb、Th和U等,亏损高场强元素（HFSE）Ta、Nb、Y和Hf等,且具有高LREE/HREE（平均5.2）的特征,类似于大陆边缘岛弧火山岩的特征。在构造环境图解中,火山岩样品落在岛弧火山岩区域内,并显示出偏向富集地幔源区演化的趋势。结合区域地质背景资料,笔者认为矿区内的火山岩应属南天山洋向伊犁-中天山板块俯冲末期大陆边缘岛弧环境的产物。

英文摘要：

Beizhan Iron Deposit occurring in Western Tianshan Mountain, were hosted primarily by late Carboniferous volcanic rocks, which mainly contain basalt, basaltic tuff, andesitic tuff, andesite and dacite, were part of high-K calc-alkaline and calc-alkaline. In this paper, representative samples of volcanic rocks from Beizhan Iiron Deposit were analyzed for major and trace elements to validate their tectonic setting. Geochemical data indicate that volcanic rocks show characteristics of light rare earth elements（LREE） enrichment and heavy rare earth elements（HREE） deficit, with the ＂Left steep right slow＂, relative enrichment large iron lithophile element（LILE; e.g., Ba, Rb, Th and U）, and negative high field-strength element（HFSE; e.g., Ta, Nb, Y and Hf） as well as highly LREE/HREE（average 5.2）,similarly with the features of continental margin arc volcanic rocks. In the plots of tectonic discrimination, the basaltic volcanic rocks are mainly projected in arc volcanic setting regions, and show the trend of evolution of enriched mantle origin region. Combined with the regional geological data, it is clear that the volcanic rocks of mine were the products of continental margin arc setting during the South-Tianshan Ocean toward north beneath the Yili-Centrel Tianshan Plate in the late stage of subduction.