投稿时间：2014-08-08
修订日期：2014-10-12
网络发布日期：2014-12-30
中文摘要:敦德铁矿床是天山成矿带内新近发现并勘查的一处大型海相火山岩型铁矿床。该矿床的矿石可划分为浸染状、稠密浸染状、条带状和块状4种主要类型。其中的条带状矿石包括磁铁矿-矽卡岩条带和磁铁矿-方解石条带2种亚类型。块状矿石内出现围岩或矽卡岩角砾时则构成角砾状矿石,其磁铁矿的成因无甚差异。根据野外观察和矿相显微研究,认为磁铁矿形成于早期矽卡岩阶段后的退化蚀变阶段,之后又被更晚的硫化物阶段和绿泥石-碳酸盐阶段的矿物叠加。敦德磁铁矿内主要发生了Al、Mn、Mg和Zn的类质同象置换,此外,也含有Ti、Si、Ca等次要元素以及Na、K、V、Cr、Ni、Co等多种可检测到的微量元素。磁铁矿内元素含量在空间上显示出直观的差异,由深部到浅部,Mn、Zn含量升高,Si、Ca、Na、K、Pb、Ba、Sr、Sb、Cu等含量降低。在TiO2-Al2O3-MgO图解、TiO2-Al2O3-(MgO+MnO)图解和Ca+Al+Mn-Ti+V图解上,敦德磁铁矿的分析数据均投影于热液交代(矽卡岩)成因区域。综上认为,该矿床的磁铁矿可能为热液充填交代成因。
Abstract:The Dunde iron ore deposit is a newly found and explored marine volcanics-hosted iron deposit in the Tianshan metallogenic belt. Magnetite ore in Dunde can be divided mainly into four types, i.e., disseminated, banded, semi-massive and massive ores. The banded ore consists of two subtypes of magnetite-skarn bands and magnetite-calcite bands. There are a few breccia ores in which wall rock or skarn fragments appear in massive ore, but the magnetite has no genetic difference. Based on field observation and microscopic study, the authors infer that magnetite crystallized at the retrograde stage after the garnet-diopside skarn stage and was replaced by later minerals of sulfide and carbonate stage. There occurred solid solution substitution of Al, Mn, Mg and Zn for Fe within the Dunde magnetite. In addition, the magnetite contains minor elements of Ti, Si and Ca and detectable trace elements of Na, K, V, Cr, Ni, Co, Zr, Pb, Ca, Ba, Sn, Sr, Sb, Cu and Sc. Element values of magnetite show obvious spatial differences of increasing Mn and Zn and decreasing Si, Ca, Na, K, Pb, Ba, Sr, Sb and Cu from the depth upward. Analytical data of Dunde magnetite fall in the region of hydrothermal replacement (skarn) in TiO2-Al2O3-MgO diagram, TiO2-Al2O3-(MgO+MnO) diagram and Ca+ Al+ Mn versus Ti + V diagram. It is concluded that the the Dunde magnetite might be of hydrothermal filling/metasomatic origin, as shown by the above evidence.
keywords:geochemistry magnetite LA-ICP-MS marine volcanics-hosted iron deposit Dunde iron deposit Western Tianshan Mountains
文章编号：
中图分类号：P618.31
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基金项目:本文得到国家自然科学基金项目(编号: 41203035)、国家重点基础研究发展计划(编号: 2012CB416803)、国家科技支撑计划(编号: 2011BAB06B02)和地质矿产调查评价项目(编号: 1212011220894-2; 1212011090300)的联合资助
引用文本：
段士刚,董满华,张作衡,蒋宗胜,李凤鸣.2014.西天山敦德铁矿床磁铁矿原位LA-ICP-MS元素分析及意义[J].矿床地质,33(6):1325~1337DUAN ShiGang,DONG ManHua,ZHANG ZuoHeng,JIANG ZongSheng,LI FengMing.2014.A LA-ICP-MS analysis of elements in magnetite from Dunde iron deposit in Western Tianshan Mountains, Xinjiang: Constraints on genesis of the deposit[J].Mineral Deposits33(6):1325~1337
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