矿床地质2012，Vol.31Issue(5)：1051-1066,16.
新疆西天山智博铁矿床蚀变矿物学、矿物化学特征及矿床成因探讨
Alteration mineralogy, mineral chemistry and genesis of Zhibo iron deposit in western Tianshan Mountains, Xinjiang
摘要
Abstract
The Zhibo iron deposit is one of the recently-discovered large magnetite deposits in the Awulale iron metal-logenic belt, which is located at the eastern corner of western Tianshan Mountains. The ore bodies are hosted mainly by volcanic and volcaniclastic rocks of the Lower Carboniferous Dahalajunshan Formation. The wall rocks of the Zhibo iron deposit have been strongly altered. Three stages of alteration assemblages and associated mineralization have been recognized: Stage I , dominantly composed of pyroxene + albite + magnetite; Stage II , characterized by amphibole + K-feldspars + epidote + magnetite + pyrite; and Stage HI, dominated by epidote + chlorite + cal-cite + quartz + pyrite + hematite ± chalcopyrite. Electron microprobe analyses indicate that the Zhibo deposit have compositional features of mineral assemblages similar to many other magmatic-hydrothermal iron oxide deposits. Pyroxene consists mainly of diopside (Di = 62.97% ~ 83.56% ) , with minor hedenbergite (Hd = 16.44% ～ 36.45%). Igneous plagioclase (Ab47.57-57.82 An415.51.87 Or0.56-0.68) has been altered into albite (Ab77.89-99.33 An0.46-2.48 Or0.21-20.3)- K-feldspar related to late hydrothermal alteration is superimposed upon the pre-existing associations. Amphiboles are entirely of actinolite composition. Abundant Fe-epidote [Fe/(Fe + Al) = 0.22～ 0.36) and minor chlorite have pervasively replaced early mineral assemblages. In contrast with high titanium (3.08% TiO2) magnetite in volcanic rocks, most magnetite from the ore bodies has lower w(TiO2) (0.23%). A small amount of disseminated magnetite has a ω(V2O5) similar to the magnetite from volcanic rocks, suggesting minor iron movement from the wall rock during the early metasomatism. Mineralogy and mineral chemistry of the altered minerals indicate that metasomatic replacement played an important role in mineralization. In addition, the Zhibo iron deposit also has some textural features suggestive of an Fe-rich melt origin for the deposit, such as the abrupt contact between the wall-rock and massive magnetite ore, the existence of significant amounts of breccia, the arrangement of magnetite that defines a flow texture, and platy magnetite. Combined with regional geology of the Awulale iron metallogenic belt, it might be suggested that Fe-rich magmatic liquids constituted the most plausible origin for the mineralization, producing massive magnetite ore bodies associated with extensive wall rock alteration. There existed a genetic relationship between late Carboniferous continental arc mag-matism and massive magnetite mineralization.关键词
地质学/矿物化学/围岩蚀变/富铁岩浆流体/智博铁矿/阿吾拉勒铁成矿带/西天山Key words
geology/ mineral chemistry/ wall rock alteration/ Fe-rich magmatic liquids/ Zhibo iron deposit/Awulale iron metallogenic belt/western Tianshan Mountains分类
天文与地球科学引用本文复制引用
蒋宗胜,张作衡,王志华,李凤鸣,田敬全..新疆西天山智博铁矿床蚀变矿物学、矿物化学特征及矿床成因探讨[J].矿床地质,2012,31(5):1051-1066,16.基金项目
本文为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)联合资助的成果 （2012CB416803）
