西昆仑切列克其菱铁矿床地质地球化学特征及其对矿床成因的制约  

Genesis of the Qieliekeqi Iron Deposit in Western Kunlun:Evidence from Geological and Geochemical Characteristics

作　　者：乔耿彪[1] 王萍 王志华[1] 伍跃中[1] 吴海才 赵晓健[1] 陈登辉[1] 

机构地区：[1]中国地质调查局西安地质调查中心,国土资源部岩浆作用成矿与找矿重点实验室,西安710054 [2]中国石油长庆油田分公司勘探开发研究院,西安710086 [3]新疆地矿局第二地质大队,新疆喀什844002

出　　处：《地质学报》2016年第10期2830-2846,共17页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号:41302051,41402079);陕西省科学技术研究发展计划项目(2014JM2-4037);国家科技支撑计划项目(编号2011BAB06B05-02,2015BAB05B01-01);中国地质调查局项目(编号:DD20160006)联合资助成果

摘　　要：新疆西昆仑切列克其菱铁矿床位于喀喇昆仑造山带的西北缘,处于我国西部著名的塔什库尔干铁矿成矿带内。近年来,切列克其铁矿的地质找矿取得较大突破,在原矿区以北新发现切北菱铁矿,矿床规模已升级为大型铁矿。鉴于该矿床的显著变化,本文拟对新的切列克其大型菱铁矿床成矿地质特征进行总结,通过大量的野外工作、镜下鉴定、矿床地球化学和稳定同位素研究确定矿床成因,为今后该区域同类型矿床的找矿勘查与地质研究工作提供参考。新的切列克其菱铁矿区共包括4个主矿群和北部隐伏矿体群(I、II、III、IV及Fe1~5),共26条矿体,主要赋存于中下志留统达坂沟群的黑云母石英片岩夹白云母片岩以及大理岩段。主矿体呈似层状、透镜状,总体走向近东西向—北西向,倾向北,倾角在22°~30°之间,矿体长度140~605m,平均厚度1.80~39.92m,全铁品位38.00%~47.52%。菱铁矿石构造多样,有代表原始沉积作用形成的块状、层状、条带状或纹层状构造和后期变质及热液叠加作用形成的假波纹、晶洞、脉状和浸染状构造。矿石最主要的结构是自形—半自形粒状变晶结构。矿石矿物主要为菱铁矿(部分被氧化成赤铁矿),矿物含量可达70%~80%或更高;脉石矿物主要为石英(10%~25%)、白云母(3%~5%)和少量黄铁矿、石墨、电气石、磷灰石等。切列克其铁矿的成矿主要经历了沉积成岩成矿期、区域变质改造期和岩浆热液叠加改造三个时期。通过对矿石的地球化学和稳定同位素分析,反映研究区志留纪为陆棚碎屑滨浅海相沉积环境;矿石样品的Al-Fe-Mn图解、轻稀土明显亏损、正Eu异常(δEu为1.54~2.82)、Ce异常不明显(δCe值为0.90~0.99)等均反映矿床具热水沉积特征;菱铁矿的δ^(18) O、δD同位素反映成矿流体叠加成因特点。综合以上因素和对其形成环境的探讨,研究认为该矿床成因属海相热水沉积�Lying in the northwestern sector of Karakorum orogenic belt,Qieliekeqi iron deposit is located in the famous Taxkorgan iron metallogenic belt of Western Kunlun area of Xinjiang.In recent years,the geological prospecting in the Qieliekeqi iron deposit makes a great progress.Qiebei iron deposit has been discovered in the north mining area and the whole deposit scale has been upgraded to a large-scale iron ore.For these reasons,based on the metallogenic geological characteristics summary,petrology,mineralogy,geochemistry and stable isotope geochemistry,this article is in the study of the genesis of ore deposit.This work is essential and important for the similar research of ore genesis in the same region.The new Qieliekeqi iron deposit include four orebodies group（Number：I,II,III,IV）and northern blind orebodies group（Number：Fe1-5）.26 orebodies are determined in these orebodies group.The main embedded stratums are biotite quartz schist,muscovite schist and marble of Middle-Upper Silurian Dabangou Group.The orebodies are broadly distributed in simple stratoid or lenticular,with stable occurrence,shallow depth and huge reserves.Siderite rocks have a massive,layered,banded structure which was mainly resulted from the original sedimentation,and a miarolitic,vein,disseminated structure which represents the late metamorphism and hydrothermal superimposition.The automorphic-hypidiomorphic granular textures are the main ore textures.The mineral composition is simple,only with original metallic minerals siderite（content 70% -80%）and ore oxide,gangue minerals quartz（10% -25%）,muscovite（3% -5%）and a few pyrites,graphites,tourmalines and apatites.The formation of this ore-deposit might be divided into three stages：initial sedimentary stage,regional metamorphic stage and hydrothermal transformation stage.Through to the forming environment research,it showed the study area in Silurian was a sedimentary environment of shallow sea facies.Not only Al-Fe-Mn diagram of ore samples indicated that the iron depos

关 键 词：热水沉积 矿床成因 地球化学 切列克其菱铁矿 西昆仑 

分 类 号：P618.31[天文地球—矿床学]