大水金矿床方解石脉微量元素地球化学特征

发布时间：2018-05-28 17:25

本文选题：大水金矿床 + 方解石脉　；参考：《成都理工大学》2015年硕士论文

【摘要】：甘肃省玛曲县大水金矿床是近几十年来在甘肃省南部西倾山地区发现的特大型金矿床,是国内外十分罕见的新类型金矿,规模大,品位高,埋藏浅,矿石成分简单,具有贫硫明显,硅化强、赤铁矿化强等特征;三叠系中统马热松多组(T2m)是该金矿的主要赋矿层位。方解石是大水金矿床与成矿最为密切相关的脉石矿物之一,其形成过程贯穿整个金成矿过程,根据野外观察以及室内分析,大水金矿床中的方解石分为矿化期前、同成矿期和矿化期后。研究方解石脉微量元素地球化学特征,对研究大水金矿床的成因有重要意义。本文在查明大水金矿床不同期次方解石地质地球化学特征基础上,研究不同期次方解石微量元素含量,相关参数,配分模式等地球化学特征,初步分析形成方解石流体来源与演化规律,方解石与成矿的关系,得出以下结论:1.大水金矿床不同期次方解石微量元素变化的趋势不大,并随成矿过程含量增加;形成方解石的流体具有多源倾向,其温度属于中低温范围;同成矿期方解石在时空上与金成矿关系最为密切。方解石脉微量元素变化可能由于其与不同围岩间微量元素的迁移;微量元素Pb、Hf、Rb、Zr、Mo、Sn、Li、Nb、Ba、Th等的富集表明这些元素与成矿密切相关,而方解石中富集的元素Sr、Cd、Cr、Ni对成矿影响不大。2.大水金矿床三期次方解石稀土元素表现为右倾,相对轻稀土富集,均表现为相对于Eu弱亏损,Ce亏损较为明显,其配分模式变化趋势大体一致,具有相似的稀土元素组成特征,稀土元素表现为不连续变化的趋势;热液体系中沉淀出的方解石相对轻富集稀土元素,暗示相对轻富集稀土元素的流体参与了方解石脉的形成;稀土元素含量:同矿化期多于矿化期前,矿化期后方解石的稀土元素含量多于同矿化期,表明方解石在沉积机制中不断有外来的稀土元素迁入,导致成矿后期方解石含量最高,Eu负异常有所降低,形成方解石过程中可能加入了相对还原环境的物质或处于相对还原的环境。经过对比,大水金矿床方解石稀土元素与原始地幔更为接近,说明形成方解石的流体来源可能与地幔流体有关,且经过较好的结晶分异作用。
[Abstract]:The great gold deposit, Maqu, Gansu Province, is an extra large gold deposit found in the West tilting mountain area of southern Gansu Province in recent decades. It is a rare new type of gold deposit at home and abroad. It has large scale, high grade, shallow buried, simple ore composition, strong sulfur poor, strong silicification, and strong hematite mineralization, and the Triassic Series T2m The main ore bearing strata of the gold deposit. Calcite is one of the most closely related gangue minerals in the great water gold deposit. Its formation process runs through the whole gold mineralization process. According to the field observation and indoor analysis, the calcite in the great water gold deposit is divided into the mineralization period, and the trace element earth of the calcite vein is studied after the metallogenic period and the mineralization period. The chemical characteristics are of great significance to the study of the genesis of the great water gold deposit. On the basis of the geological and geochemical characteristics of the different stages of the calcite in the Da Shui gold deposit, this paper studies the geochemical characteristics of the trace elements of the calcite at different stages, the related parameters, the distribution pattern and so on, and the origin and evolution of the calcite fluid is formed by the initial step. The following conclusions are drawn as follows: the change trend of trace elements in the 1. great gold deposits at different stages of the calcite is little, and increases with the content of the metallogenic process; the formation of calcite fluid has a multi source tendency, and its temperature belongs to the middle and low temperature range; the calcite in the same metallogenic period is most closely related to the gold mineralization in the time and space. The change of trace elements may be due to the migration of trace elements between different surrounding rocks, and the enrichment of trace elements Pb, Hf, Rb, Zr, Mo, Sn, Li, Nb, Th, etc. indicates that these elements are closely related to the mineralization, while the elements enriched in calcite are Sr, Cd, and minerals are right, relative to the three calcite. The enrichment of light rare earth shows that the loss of the Eu is relatively weak, and the loss of Ce is more obvious. The distribution pattern of the distribution of rare earth elements is the same, with similar rare earth elements, and the rare earth element shows a trend of discontinuous change; the precipitated calcite in the hydrothermal system is relatively light enrichment of the rare earth elements, suggesting a relatively light enrichment of the flow of rare earth elements. The body participates in the formation of calcite veins, and the content of rare earth elements: the content of rare earth elements in the same mineralization period is more than that of the mineralization period, and the REE content of the calcite in the rear of the mineralization is more than that of the same mineralization period. It indicates that the calcite has been moved into the sedimentary mechanism, and the content of calcite has the highest content in the later period of the mineralization, and the negative Eu abnormality is reduced to form calcite. By contrast, the rare-earth elements of calcite in the great water gold deposit are more closely related to the original mantle, indicating that the source of the formation of calcite may be related to the mantle fluid and through better crystallization differentiation.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51

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