本文選題：礦床特征　切入點(diǎn)：穩(wěn)定同位素　出處：《成都理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：甘肅省瑪曲縣大水金礦床是90年代初在甘肅省南部西傾山地區(qū)發(fā)現(xiàn)的國(guó)內(nèi)外十分罕見(jiàn)的富赤鐵礦硅質(zhì)巖型金礦類型。該金礦不僅礦床規(guī)模大、品位高、埋藏淺、礦石成分簡(jiǎn)單、易采易選,且礦化特征極為獨(dú)特。目前,國(guó)內(nèi)外對(duì)該類型金礦床的研究程度較低,對(duì)此類礦床的深入研究有利于進(jìn)一步認(rèn)識(shí)西秦嶺造山帶構(gòu)造演化歷史和成礦規(guī)律,也有利于整個(gè)秦嶺造山帶地區(qū)礦產(chǎn)勘查評(píng)價(jià)工作,同時(shí)也有利于尋找新的大水式富赤鐵礦硅質(zhì)巖型金礦勘探工作的深入開(kāi)展,并有利于研究金礦成礦機(jī)理和深化成礦理論。大水金礦田位于甘肅省西秦嶺晚古生代-中生代多金屬成礦帶上,前人已對(duì)其做了大量的研究,在成礦構(gòu)造,成礦動(dòng)力,成礦年齡等方面取得了重要成果,但對(duì)本金礦的成礦流體來(lái)源以及成礦模式缺乏確切的論證。大量研究資料表明,復(fù)雜成因的大水金礦在時(shí)域上,地域上都與穩(wěn)定同位素密切相關(guān),因此,穩(wěn)定同位素的研究有利于解決大水金礦的成礦流體來(lái)源,進(jìn)一步認(rèn)識(shí)西秦嶺構(gòu)造帶的成礦規(guī)律,也有利于完善金礦床的成礦機(jī)制理論。本文首先調(diào)研了大水金礦的區(qū)域地質(zhì)背景,礦區(qū)地質(zhì)特征,礦床地質(zhì)特征,闡述了大水金礦的穩(wěn)定同位素地球化學(xué)特征,確定了本次研究以方解石,灰?guī)r,硅質(zhì)巖為研究對(duì)象,測(cè)定了方解石,灰?guī)r碳氧鍶同位素組成,并借以方解石水—巖理論方法進(jìn)行模擬。得出以下結(jié)論:(1)大水金礦方解石的的碳氧同位素地球化學(xué)特征,推測(cè)出成礦流體可能來(lái)源于深源。方解石氧同位素地球化學(xué)特征,推測(cè)出早期流體與巖漿活動(dòng)有關(guān),晚期流體與大氣降水有關(guān)。(2)Sr同位素組成在探討成礦物質(zhì)來(lái)源方面也能發(fā)揮重要作用,大水金礦的鍶同位素地球化學(xué)特征,推測(cè)出硅化灰?guī)r可能來(lái)源于殼�；旌蠀^(qū)。(3)大水金礦圍巖與礦石的CaO和SiO2呈明顯的負(fù)相關(guān),因此,可進(jìn)行水巖反應(yīng)模擬,模擬顯示,大水金礦成礦流體的可溶性碳以H2CO3為主,早期流體的碳可能來(lái)自于深源,晚期流體有大氣降水加入,大水金礦的形成溫度與流體包裹體測(cè)溫一致,為中低溫?zé)嵋旱V床。通過(guò)分析穩(wěn)定同位素地球化學(xué)特征,可以認(rèn)為,大水金礦的成礦流體來(lái)源很復(fù)雜,可能多種成因?yàn)槌傻V流體提供了物源,此外,淺部熱液也對(duì)成礦具有重要作用。
[Abstract]:The Dashui gold deposit in Maqu County, Gansu Province, is a very rare type of hematite rich siliceous type gold deposit found in Xidushan area of southern Gansu Province in the early 1990s. This gold deposit is not only large in scale, high in grade, shallow in burial, but also simple in ore composition. At present, the degree of research on this type of gold deposit at home and abroad is relatively low, and the further study of this kind of deposit is helpful to further understand the tectonic evolution history and metallogenic law of the West Qinling orogenic belt. It is also conducive to the exploration and evaluation of mineral resources in the entire Qinling orogenic belt and to the further development of the exploration work for new large water hematite rich siliceous rock type gold deposits. The Dashui gold ore field is located in the late Paleozoic and Mesozoic polymetallic metallogenic belt in the West Qinling Mountains of Gansu Province. Important achievements have been made in ore-forming age, but the source of ore-forming fluid and metallogenic model of the gold deposit are not proved exactly. A large number of research data show that the gold deposit with complex genesis is in time domain. Therefore, the study of stable isotopes is helpful to solve the source of ore-forming fluid of Dashui gold deposit and to further understand the metallogenic regularity of the West Qinling tectonic belt. In this paper, the regional geological background, the geological characteristics of the ore area and the geological characteristics of the deposit are investigated, and the stable isotope geochemical characteristics of the Dashui gold deposit are expounded. It has been determined that the calcite, limestone and siliceous rocks are the objects of this study. The isotopic compositions of calcite and limestone are determined. The following conclusions can be drawn from the following conclusions: (1) the carbon and oxygen isotopic geochemical characteristics of calcite in Dashui gold deposit, and it is inferred that the ore-forming fluid may have originated from deep source. The oxygen isotope geochemical characteristics of calcite may be derived from the ore-forming fluid. It is inferred that the early fluid is related to magmatic activity, and the late fluid is related to precipitation. Sr isotopic composition may also play an important role in exploring the source of ore-forming materials, and the geochemical characteristics of strontium isotope of Dashui gold deposit. It is inferred that silicified limestone may originate from the crust-mantle mixed area. 3) the surrounding rock of Dashui gold deposit is negatively correlated with the CaO and SiO2 of the ore. Therefore, the water rock reaction can be simulated, and the simulation shows that the soluble carbon of the ore-forming fluid in the Dashui gold deposit is mainly H2CO3. The carbon of the early fluid may come from the deep source, the late fluid has the addition of atmospheric precipitation, the formation temperature of the Dashui gold deposit is consistent with the temperature of fluid inclusions, and it is a middle-low temperature hydrothermal deposit. By analyzing the geochemical characteristics of stable isotopes, it can be concluded that, The source of ore-forming fluid in Dashui gold deposit is very complex, and there may be many kinds of ore-forming fluids that provide material source. In addition, shallow hydrothermal fluid also plays an important role in mineralization.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P618.51

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本文編號(hào)：1644868