本文關(guān)鍵詞： 大興安嶺南段 北三段礦區(qū) 地球化學(xué) 穩(wěn)定同位素 找礦預(yù)測(cè)　出處：《中國(guó)地質(zhì)大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：大興安嶺南段位于中亞造山帶的東段,古亞洲洋、蒙古-鄂霍茨克洋和古太平洋構(gòu)造-成礦域的疊加部位,構(gòu)造位置特殊,發(fā)現(xiàn)有豐富的金屬礦產(chǎn)資源。北三段礦區(qū)是大興安嶺南段西部的一個(gè)多金屬礦區(qū)。本文通過(guò)野外調(diào)查、地球化學(xué)分析、穩(wěn)定同位素、流體包裹體研究,結(jié)合區(qū)域地質(zhì)背景及區(qū)域成礦特點(diǎn),對(duì)北三段礦區(qū)成礦流體來(lái)源、成礦物質(zhì)來(lái)源進(jìn)行研究,進(jìn)而進(jìn)行找礦前景分析。地球化學(xué)化學(xué)特征表明,北三段礦區(qū)出露花崗巖巖脈為A型花崗巖,其形成環(huán)境為碰撞造山后伸展環(huán)境。煌斑巖脈超鉀質(zhì)煌斑巖類,其Si O2含量為41.09~41.47%,表明來(lái)源于地幔,而Ta/La值遠(yuǎn)低于原始地幔值,表明其可能存在地殼物質(zhì)的參與。輝綠巖脈的Mg O、Cr、Ni、(Tb/Yb)N值均低于原始地幔值,指示其源區(qū)不是原生巖漿,而是結(jié)晶分異作用的尖晶石橄欖巖巖漿;其La/Yb1.2、La/Ta大于22,Ti O2為0.93~1.20%,遠(yuǎn)低于軟流圈玄武質(zhì)巖漿的平均值,表明其主要來(lái)源于巖石圈地幔。碳、氧同位素表明北三段礦區(qū)成礦流體來(lái)源為地幔巖漿,后期受到大氣降水的影響,成礦流體為大氣降水、巖漿水的混合;氫氧同位素特征亦表明北三段成礦流體同時(shí)受巖漿水及大氣降水影響,大氣降水的參與從成礦流體出溶后就開(kāi)始了。北三段礦區(qū)的硫同位素變化范圍為-0.24‰~2.37‰,均值為1.29‰,極差、標(biāo)準(zhǔn)差小,變化范圍狹窄,與大興安嶺南段金屬礦床的硫同位素特征相似,表明硫來(lái)源于深源巖漿。在208Pb/204Pb-206Pb/204Pb和207Pb/204Pb-206Pb/204Pb圖解中,北三段樣品基本落在下地殼、上地幔和造山帶鉛的演化線附,且基本排列為一條直線,表明它們來(lái)源于同一巖漿源區(qū),成礦物質(zhì)由造山帶物質(zhì)和地幔物質(zhì)兩部分提供。北三段礦區(qū)與鄰區(qū)大井礦床具有一定的相似性,其硫鉛同位素特征基本一致,表明其具有相同的成礦物質(zhì)來(lái)源;而其碳?xì)溲跬凰靥卣飨嗨票砻髌渚哂邢嗤某傻V流體來(lái)源,是同一體系不同條件形成的不同礦床,均為熱液型礦床。北三段礦區(qū)脈巖多為淺成侵入巖,大井礦床多為中酸性噴出巖,從成礦溫度來(lái)看,大井礦床比本區(qū)成礦溫度高,結(jié)合區(qū)域大地構(gòu)造背景,北三段深部地區(qū)可能存在大井礦床類似的銅多金屬礦床。礦區(qū)內(nèi)北西向斷裂發(fā)育區(qū)域及脈巖出露區(qū)域亦為找礦有利部位。
[Abstract]:The southern part of the Daxing'anling Mountains is located in the eastern part of the Central Asian orogenic belt, the Paleo-Asian Ocean, the Mongolia-Okhotsk Ocean and the paleo-Pacific tectonic-metallogenic region. It is found that there are abundant metal mineral resources. The northern third section is a polymetallic mining area in the west of Daxinganling Mountains. Through field investigation, geochemical analysis, stable isotopes and fluid inclusions, Combined with the regional geological background and regional metallogenic characteristics, the source of ore-forming fluid and ore-forming material in the third section of the northern part of China is studied, and the prospect of prospecting is analyzed. The geochemical and chemical characteristics show that, The outcropping granite veins in the Beisanjie mining area are A-type granites and formed in a post-collisional extensional environment. The ultrapotash lamprophyres of the lamprophyre veins have a Sio _ 2 content of 41.09 ~ 41.47, indicating that they originated from the mantle, while the Ta/La value is much lower than the original mantle value. The results indicate that there is a possible involvement of crustal material in the diabase veins, and the mg _ O _ O _ Cr-Ni _ (B) T _ (b / Y) N values of the diabase veins are all lower than the original mantle values, indicating that the source region is not primary magma, but the spinel peridotite magma of crystallization differentiation. The La- / Yb _ (1.2) / Ta ~ (-1 / Ta) is 0.93 / 1.20, which is far lower than the average value of the asthenospheric Black Tortoise magma, which indicates that the ore forming fluid in the third member of the northern ore area is derived from mantle magma, which is influenced by the atmospheric precipitation in the later stage, and the carbon and oxygen isotopes indicate that the ore-forming fluid of the northern third member ore area is derived from mantle magma. The ore-forming fluid is the mixture of magmatic water and meteoric water, and the hydrogen and oxygen isotopic characteristics also indicate that the ore-forming fluid in the northern third member is affected by both magmatic water and atmospheric precipitation. The participation of atmospheric precipitation begins after the ore-forming fluid dissolves. The range of sulfur isotopic variation in the North third member mining area is -0.24 鈥，

本文編號(hào)：1503226