本文選題：大水金礦床 + 方解石脈�。� 參考：《成都理工大學(xué)》2015年碩士論文

【摘要】：甘肅省瑪曲縣大水金礦床是近幾十年來在甘肅省南部西傾山地區(qū)發(fā)現(xiàn)的特大型金礦床,是國內(nèi)外十分罕見的新類型金礦,規(guī)模大,品位高,埋藏淺,礦石成分簡單,具有貧硫明顯,硅化強(qiáng)、赤鐵礦化強(qiáng)等特征;三疊系中統(tǒng)馬熱松多組(T2m)是該金礦的主要賦礦層位。方解石是大水金礦床與成礦最為密切相關(guān)的脈石礦物之一,其形成過程貫穿整個(gè)金成礦過程,根據(jù)野外觀察以及室內(nèi)分析,大水金礦床中的方解石分為礦化期前、同成礦期和礦化期后。研究方解石脈微量元素地球化學(xué)特征,對研究大水金礦床的成因有重要意義。本文在查明大水金礦床不同期次方解石地質(zhì)地球化學(xué)特征基礎(chǔ)上,研究不同期次方解石微量元素含量,相關(guān)參數(shù),配分模式等地球化學(xué)特征,初步分析形成方解石流體來源與演化規(guī)律,方解石與成礦的關(guān)系,得出以下結(jié)論:1.大水金礦床不同期次方解石微量元素變化的趨勢不大,并隨成礦過程含量增加;形成方解石的流體具有多源傾向,其溫度屬于中低溫范圍;同成礦期方解石在時(shí)空上與金成礦關(guān)系最為密切。方解石脈微量元素變化可能由于其與不同圍巖間微量元素的遷移;微量元素Pb、Hf、Rb、Zr、Mo、Sn、Li、Nb、Ba、Th等的富集表明這些元素與成礦密切相關(guān),而方解石中富集的元素Sr、Cd、Cr、Ni對成礦影響不大。2.大水金礦床三期次方解石稀土元素表現(xiàn)為右傾,相對輕稀土富集,均表現(xiàn)為相對于Eu弱虧損,Ce虧損較為明顯,其配分模式變化趨勢大體一致,具有相似的稀土元素組成特征,稀土元素表現(xiàn)為不連續(xù)變化的趨勢;熱液體系中沉淀出的方解石相對輕富集稀土元素,暗示相對輕富集稀土元素的流體參與了方解石脈的形成;稀土元素含量:同礦化期多于礦化期前,礦化期后方解石的稀土元素含量多于同礦化期,表明方解石在沉積機(jī)制中不斷有外來的稀土元素遷入,導(dǎo)致成礦后期方解石含量最高,Eu負(fù)異常有所降低,形成方解石過程中可能加入了相對還原環(huán)境的物質(zhì)或處于相對還原的環(huán)境。經(jīng)過對比,大水金礦床方解石稀土元素與原始地幔更為接近,說明形成方解石的流體來源可能與地幔流體有關(guān),且經(jīng)過較好的結(jié)晶分異作用。
[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.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P618.51

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