投稿时间：2024-06-21
修订日期：2025-02-15
网络发布日期：2025-07-01
中文摘要:新疆萨尔托海铬铁矿矿床经历了强烈后期热液蚀变作用，发育4类铬铁矿：① 原生铬尖晶石；② 多孔铬铁矿；③ 多孔铁铬铁矿；④ 均质铁铬铁矿。原生铬尖晶石结构均一，属高铝铬尖晶石。多孔铬铁矿呈交代边包裹原生铬尖晶石，具有较原生铬尖晶石明显更高的Cr#值和更低的Mg#值。多孔铁铬铁矿呈单一颗粒，比多孔铬铁矿具有更高的Cr#值和更低的Mg#值，且Fe2+含量明显增加。均质铁铬铁矿以增生边形式出现，其Fe3+含量最高。在MORB铬铁矿标准化蛛网图中，原生铬尖晶石的微量元素配分模式呈无明显异常的“平坦”型；而多孔铬铁矿表现出明显的Ni、Sc亏损和轻微的Zn、Co、Mn富集；多孔铁铬铁矿和均质铁铬铁矿则强烈富集Zn、Co、Mn、Ni而亏损Ga、Sc。结构和成分的变化特征表明，原生铬尖晶石经历了两阶段流体交代作用。第一阶段，原生铬尖晶石和橄榄石在低硅还原流体作用下反应形成多孔铬铁矿；随后，在高硅还原流体作用下，多孔铬铁矿与橄榄石反应形成多孔铁铬铁矿；第二阶段，多孔铁铬铁矿与富Fe3+的氧化性流体在角闪岩相下反应形成均质铁铬铁矿。
Abstract:The Sartohay chromite deposit in Xinjiang underwent intense late-stage hydrothermal alteration, resulting in the formation of four types of chromite: ① Primary Cr-spinel; ② Porous chromite; ③ Porous ferrous chromite; ④ Homogeneous ferrous chromite. The primary Cr-spinel shows a uniform texture, compositionally belonging to high-Al Cr-spinel. The porous chromite occurs as the irregular metasomatic rims that enclosed the primary Cr-spinel, having significantly increased Cr# and decreased Mg# values. The porous ferrous chromite appears as single grains, having higher Cr# values, lower Mg# values, and much higher Fe2+ contents than the porous chromite. Homogeneous ferrous chromite, which has the highest Fe3+ contents, typically appears as overgrown rims. In the MORB chromite normalized spider diagram, the trace element patterns of the primary chromite spinel are generally "flat" with no significant anomalies, while the porous chromite shows obvious depletion of Ni and Sc and slight enrichment of Zn, Co, and Mn. The porous ferrous chromite and homogeneous ferrous chromite are strongly enriched in Zn, Co, Mn and Ni, and depleted in Ga and Sc. These textural and compositional features suggest that the primary Cr-spinel has undergone a two-stage fluid-mediated alteration process. In the first stage, the primary Cr-spinel and olivine interact with reducing low-silica fluids to form porous chromite. Subsequently, porous chromite reacted with olivine to produce porous ferrous chromite in the presence of a high-silica-reducing fluid. During the second stage, the porous ferrous chromite interacted with ferrous oxidized fluids to form homogeneous ferrous chromite under amphibolite facies condition.
keywords:fluid trace element chromite metamorphism Sartohay
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基金项目:本文得到自治区重点研发项目（编号:2023B03006）、新疆维吾尔自治区人民政府国家305项目办公室和新疆维吾尔自治区“天池英才”引进计划联合资助
引用文本：
赵佳玉,申萍,冯浩轩,李昌昊,罗耀清,武阳,楚翔凯,索青宇,白应雄.2025.新疆萨尔托海豆荚状铬铁矿后期蚀变作用[J].矿床地质,44(3):559~580ZHAO JiaYu,SHEN Ping,FENG HaoXuan,LI ChangHao,LUO YaoQing,WU Yang,CHU XiangKai,SUO QingYu,BAI YingXiong.2025.Hydrothermal alteration of Sartohay podiform chromite, Xinjiang[J].Mineral Deposits44(3):559~580
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