中国地质Issue(6)：1833-1852,20.
新疆西天山式可布台铁矿地质、矿物化学和S同位素特征及其对矿床成因的约束
Geology, mineral chemistry and sulfur isotope geochemistry of the Shikebutai iron deposit in West Tianshan Mountains, Xinjiang:Constraints on genesis of the deposit
摘要
Abstract
The Shikebutai iron deposit is hosted in Upper Carboniferous intermediate-acidic volcaniclastic rocks, low-grade metamorphic schist and phyllite in the Yili rifting of West Tianshan Mountains. Stratiform, stratoid and phacoidal orebodies are distributed along the strata. Ore minerals are predominantly hematite and specularite, with small amounts of pyrite and siderite, whereas gangue minerals are dominated by jasper, barite and quartz, with a small quantity of calcite. The ores display banded, lamellar and massive structures. Ore minerals usually show cryptocrystalline, filling and subhedral textures. The ore-forming process of the Shikebutai iron deposit can be divided into four stages, i.e., pyrite-hematite-jasper-barite stage, siderite-pyrolusite stage, quartz-specularite stage and oxide minerals stage. Geological characteristics of lamellar structure and the distribution along the strata indicate that the formation of the Shikebutai iron deposit was related to sedimentation. Electron microprobe analyses show that hematite from massive ore has variable Al2O3, Na2O, Mgo and SiO2 values, which suggests that massive hematite ores are products of rapid sedimentation and crystallization, and also implies the rapid extravasation of iron-rich fluids. Nevertheless, hematite from lamellar ore and banded ore have concentrated Al2O3, Na2O, Mgo and SiO2 values, suggesting that they formed in calm sedimentary environment with slow extravasation of iron-rich fluids. In general, the extravasation rate of mineral-rich fluid and the sedimentary environment changed continuously during the metallogenic process. The high Co-Ni ratio of pyrite shows that it was derived from volcanism. A negative correlativity between FeOT and MnO+MgO is found in siderite which can be divided into two groups corresponding respectively to two different types of siderite under microscope. These phenomena imply that siderite experienced a process of differentiation at the late metallogenic stage. Theδ34S values of pyrite range from-6.1‰ to 6.5‰and the value of barite is 12.9‰, which indicates that the sulfur was derived from magma, and it was subjected to fractionation between sulfide and sulfate. In summary, the Shikebutai iron deposit belongs to submarine volcanic exhalative-sedimentary high-grade iron deposit.关键词
赤铁矿/电子探针/硫同位素/地质特征/式可布台/海相火山岩型铁矿Key words
hematite/electron microprobe analysis/sulfur isotope/ore deposit geology/Shikebutai/marine volcanics-hosted iron deposits分类
天文与地球科学引用本文复制引用
陈杰,段士刚,张作衡,罗刚,蒋宗胜,骆文娟,王大川,郑仁乔..新疆西天山式可布台铁矿地质、矿物化学和S同位素特征及其对矿床成因的约束[J].中国地质,2014,(6):1833-1852,20.基金项目
国家科技支撑计划（2011BAB06B02）、国家自然科学基金项目（41203035）、国家重点基础研究发展计划（2012CB416803）和中国地质调查局地质矿产调查评价项目（1212011090300）联合资助。 （）
