| 论安徽省姑山铁矿床的热液成矿特征 |
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| 引用本文：.1988.On the hydrothermal origin of the Gushan iron ore deposit in Anhui province[J].Mineral Deposits,7(2):21~30 |
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| 中文摘要:姑山铁矿床产在燕山期辉石闪长岩与中三叠统黄马青组砂页岩的接触带上。矿石具有典型的斑状、球颗状和骨架状结构。镜下研究表明，这些结构不是矿浆结晶的产物，而是热液成因微晶赤铁矿在后期地质过程中发生变晶生长所致。矿床中的蚀变和矿化自下而上呈现规律性的分带。碳酸盐化是特征性的蚀变类型，其形成与成矿密切有关，并可作为一种近矿找矿标志。在热液成矿过程中，辉石闪长岩中的铁很可能以羰基络合物的形式发生活化转移。在热液演化过程中由于氧逸度的升高和碱度、压力的降低，羰基络合物发生分解而使铁在接触带附近沉淀成矿。 |
| 中文关键词:铁矿石 热液矿床 活化转移 安徽姑山 |
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| On the hydrothermal origin of the Gushan iron ore deposit in Anhui province |
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| Abstract:The Gushan iron deposit, located at the south end of the Nanjing-Wuhu Mesozoic terrestrial volcanic-sedimentary basin, is one of the most important iron ore sources in East China. A subvolcanic augite diorite stock here intruded into the Triassic siltstones, sandstones and shales which, along with the Jurassic sandstones, formed the basement underlying the andesitic volcanic. The intensely brecciated sedimentary rocks along the contact zone provided the main structure for ore deposition. The major components of the ores are hematite(martite), quartz, chalcedony and carbonates. Hydrothermal alterations are extensively developed in this deposit and can be divided upwards from the lowest unaltered augite diorite into four zones: (1) albitized augite diorite, (2) carbonatized augite diorite,(3) siliceous or carbonate-bearing iron ores and (4) carbonatized sedimentary rocks. The widespread carbonate minerals within, below and above the orebodies and a considerable amount of reductive gases such as CH4, CO and H2 contained in the inclusions of the ore minerals indicate that carbonyl complexes may have been the important form for the remobilization of iron in augite diorite during the post-magmatic processes. In reducing environments, carbon monoxide call break down iron-bearing minerals in the parent rocks and combine with iron released from these minerals into iron carbonyls such as Fe(CO)5, which will be dissolved in soda-rich alkaline solutions and be transported in iron carbonylate Na2Ee(CO)4. The progressive acidification of the ore-transporting fluid caused by albitization will transform iron carbonylate into carbonyl hydrite H2Fe(CO)4, which is unstable in relatively oxidizing environments and ready to be decomposed to form iron oxide precipitation. |
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