矿床地质2012，Vol.31Issue(5)：983-998,16.
西天山智博铁矿床磁铁矿成分特征及其矿床成因意义
Magnetite composition of Zhibo iron deposit in Western Tianshan Mountains and its genetic significance
摘要
Abstract
Located in the eastern Awulale metallogenic belt of Western Tianshan Mountains, the large-size Zhibo iron deposit is hosted in basaltic andesite, andesite and pyroclastic rocks of the Lower Carboniferous Dahalajunshan Formation. The Zhibo iron deposit consists of four main areas: the eastern zone, the middle zone, the western zone, and No. 13 ore body, in which the ore bodies occur as layers, strafeid bodies or lenses. Mineralization consists of massive magnetite associated with minor disseminations of pyrite and veinlets of hematite and trace chal-copyrite. The ore structures include mainly massive and disseminated, subordinately brecciated, and occasionally banded or vein-stockwork forms, whereas the ore textures consist of ubhedral - anhedral grainular, metasomatic relict, and platy forms. The principal alteration mineral assemblages in Zhibo include diopside, albite, K-feldspar, epidote, and actinolite, together with calcite, quartz, chlorite and titanite. On the basis of observed mineral assemblages and ore textures as well as mineral analyses, two periods of ore deposition have been recognized: magmatic period and hydrothermal ore-forming period, which could be further subdivided into three metallogenic stages, i.e., magnetite-diopside-epidote stage (a1), magnetite-K-feldspar-epidote stage (bl) and quartz-sulfide stage (b2). Electron microprobe analyses show that the magnetite with magmatic features has higher content of FeOT and lower content of Al2O3, CaO, MgO, SiO2 in comparison with the magnetite with hydrothermal features. The content of V2O5 in brecciated and disseminated ore is relatively high, similar to the content of volcanic rocks, suggesting that part of iron of the ore-forming stage came from the wall rock. Massive and disseminated magnetite has varied FeOT values, mostly above 90% ; FeOT content of magnetite from brecciated, veined and dendritic ores varies between 90% and 92% ; the FeOx content of magnetite from laminated ore varies between 88 % and 92 %, with higher average content of other oxides such as CaO and SiO2. Both ternary plot of TiO2-Al2O3-MgO and Ca + Al + Mn versus Ti + V discriminant diagram suggest that the formation of the Zhibo iron deposit was associated with volcanic activity and hydrothermal metasomatism of magmatic-hydrothermal fluid.关键词
地质学/地质特征/磁铁矿/电子探针/智博铁矿/西天山Key words
geology/geological features/magnetite/EMPA/Zhibo iron deposit/Western Tianshan Mountains分类
天文与地球科学引用本文复制引用
王志华,张作衡,蒋宗胜,洪为,田敬全..西天山智博铁矿床磁铁矿成分特征及其矿床成因意义[J].矿床地质,2012,31(5):983-998,16.基金项目
本文受到国家重点基础研究发展计划(2012CB416803)、国家科技支撑计划(2011BAB06B02-05)和地质矿产调查评价项目(1212011085060)联合资助 （2012CB416803）
