东天山红云滩铁矿床矿物学、矿物化学特征及矿床成因探讨  

Mineralogy,mineral chemistry and genesis of the Hongyuntan iron deposit in East Tianshan Mountians,Xinjiang

作　　者：张立成[1,2] 王义天[2] 陈雪峰[3] 马世青[3] 王志华[2] 余长发[2] 

机构地区：[1]辽宁省冶金地质勘查局地质勘查研究院,辽宁鞍山114000 [2]国土资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,北京100037 [3]新疆维吾尔自治区地质矿产勘查开发局第一地质大队,新疆鄯善838204

出　　处：《岩石矿物学杂志》2013年第4期431-449,共19页Acta Petrologica et Mineralogica

基　　金：中国地质调查局地质调查工作项目(1212011085527)

摘　　要：东天山红云滩铁矿赋存于下石炭统雅满苏组火山碎屑岩地层中。矿体主要呈层状、似层状、透镜状。矿石矿物以大量磁铁矿为主,含少量的磁赤铁矿、镜铁矿、黄铁矿和极少量的黄铜矿等。脉石矿物主要有石榴石、透辉石、阳起石、绿帘石、绿泥石、黑云母、钠长石、石英等。矿石构造以块状构造和浸染状构造为主,局部为条带状构造、脉状构造;矿石结构包括半自形-他形粒状结构、交代结构。围岩蚀变对称分带明显,从矿(化)体到两侧围岩,蚀变呈现从深色到浅色的变化现象。根据矿物共生组合、矿石组构的观察,本次工作识别出矽卡岩期和热液期两个成矿期,进一步细分为4个成矿阶段:矽卡岩阶段、退化蚀变阶段(主成矿期)、热液早期阶段及石英-硫化物阶段。电子探针分析表明石榴石端员组分以钙铁榴石-钙铝榴石系列为主,辉石端员组分以透辉石-钙铁辉石为主,角闪石端员组分主要为阳起石和透闪石,这些特点表明矿区矽卡岩为热液交代钙矽卡岩。磁铁矿的主、微量元素特征表明其形成与矽卡岩密切相关。结合成矿地质特征,认为矽卡岩是由富铁岩浆热液流体沿断裂构造运移、交代下石炭统雅满苏组富钙火山碎屑岩地层而形成的,磁铁矿的形成与矽卡岩的退化变质作用有关。The Hongyuntan iron deposit is hosted in pyroclastic rocks of the Lower Carboniferous Yamansu Formation. The ore bodies occur as layers, stratoid bodies or lenses. The principal ore mineral is magnetite, together with minor maghemite, specularite, pyrite and trace chalcopyrite. The gangue minerals include garnet, diopside, actinolite, chlorite, tremolite, epidote, biotite, albite and quartz. The ore structures are mainly of massive and disseminated forms, with occasional banded or veined forms. The ore textures are of subhedral-anhedral granular and metasomatic types. The wall rock alteration shows symmetrical zoning, and the alteration colors change from dark to light from ore bodies outwards. On the basis of observed mineral assemblages and ore fabrics, two periods of ore deposition were recognized, i.e., skarn period and hydrothermal ore-forming period, which could be further subdivided into four metallogenic stages, namely skarn stage, retrograde alteration stage （main ore-forming stage）, early hydrothermal stage and quartz-sulfide stage. Electron microprobe analyses show that the end member of garnet is mainly andradite-grossularite. The composition of pyroxene is mainly diopside-asteroite. The amphiboles is composed mainly of actinolite and tremolite with minor magnesiohornblende. The composition of these skarn minerals suggests that skarn in the Hongyuntan iron deposit is calcic skarn, belonging to metasomatic skarn. The characteristics of main and trace elements suggest that the formation of magnetite was closely related to the skarn. In combination with geological characteristics, the authors suggest that the skarn might have resulted from interaction between Ca-rich pyroclastic and Fe-rich magmatic hydrothermal fluid which was transported along the fault system. The formation of magnetite was hence related to the regressive metamorphism of the skarn.

关 键 词：磁铁矿 矽卡岩 化学组分标型 红云滩铁矿床 东天山 

分 类 号：P578.46[天文地球—矿物学] P575.1[天文地球—地质学]