西北地质2026，Vol.59Issue(5)：131-143,13.DOI:10.12401/j.nwg.2026067
西昆仑老并铁矿床磁铁矿矿物化学组成特征及其对成矿作用的约束
Chemical Composition of Magnetite from the Laobing Iron Deposit in West Kunlun,and Its Constraints on Ore Formation
摘要
Abstract
The Taxkorgan area is an important iron metallogenic belt in western China.The Laobing iron de-posit,one of the typical deposits in this belt,is characterized by the assemblage of magnetite,gypsum and sul-fides,serving as an ideal proxy for investigating the iron mineralization processes in this region.Based on de-tailed field geological investigation,this study presents LA-ICP-MS in situ trace element analyses of three types of magnetite with different occurrences from the Laobing iron deposit,aiming to constrain the ore-forming mate-rial sources,physicochemical conditions and deposit genesis.The results show that the three types of magnetite display consistent trace element spider diagram patterns,which are comparable to those of high-temperature hy-drothermal deposits,indicating that the ore-forming materials were derived from submarine high-temperature hydrothermal fluids.The(Al+Mn)-(Ti+V)geothermometer and Ga-MgO diagram indicate that Mag-1 and Mag-2 crystallized at approximately 300℃,whereas Mag-3 was modified by post-ore metamorphism,recording high-er re-equilibration temperatures.The pronounced enrichment of Al,Ti and V,together with elevated Ni/Cr ra-tios and low Ti/V ratios in magnetite,jointly suggest crystallization under relatively reducing conditions,with oxygen fugacity exhibiting a systematic decrease from Mag-1 to Mag-3.The V+Ti and Al+Mn+Ca contents of magnetite from the Laobing deposit are significantly higher than those of BIF-type magnetite,while being more comparable to hydrothermal-type magnetite.Combined with the presence of abundant gypsum-bearing layers re-lated to marine sedimentation in the mining area,this study proposes that the Laobing deposit formed in a sub-marine high-temperature hydrothermal system during the Early Cambrian,experiencing early submarine hy-drothermal iron precipitation and late restricted basin gypsum-salt deposition,followed by post-ore regional metamorphic overprinting.关键词
磁铁矿/矿物化学/老并铁矿床/西昆仑造山带Key words
magnetite/mineral chemistry/Laobing iron deposit/West Kunlun Orogenic Belt分类
天文与地球科学引用本文复制引用
宋明伟,彭义伟,章永梅,顾雪祥,张英帅,董树义,陈力,罗潇..西昆仑老并铁矿床磁铁矿矿物化学组成特征及其对成矿作用的约束[J].西北地质,2026,59(5):131-143,13.基金项目
深地国家科技重大专项(2024ZD1001806)资助. （2024ZD1001806）
