本文選題：尼雄礦田 + 矽卡巖型鐵��； 參考：《中國地質科學院》2015年碩士論文

【摘要】：尼雄鐵銅礦田由北西至南東方向劃分為5個礦區(qū)：滾糾鐵礦區(qū)、尼雄鐵礦區(qū)、沙松南鐵礦區(qū)、毛加崍鐵礦區(qū)及日阿銅礦區(qū)。本文主要分析了西藏尼雄鐵銅礦田中尼雄鐵礦區(qū)的成礦花崗閃長巖以及日阿銅礦區(qū)的成礦二長花崗斑巖的主量元素、微量元素、稀土元素及Sr-Nd-Pb同位素特征,并做了鋯石LA-ICPMS U-Pb年齡測定。取得主要成果如下： (1)尼雄鐵礦區(qū)的成礦花崗閃長巖巖石地球化學分析結果顯示為亞鋁質中鉀-高鉀鈣堿性巖系列,屬Ⅰ-型花崗巖；地球化學上該巖體富集大離子親石元素(LILE)Rb、Ba、Sr、Th、U、K, Pb,虧損高場強元素(HFSE) Nb、Ta, Ti,具有典型的島弧巖漿作用的特征；稀土元素球粒隕石標準化圖表現(xiàn)為輕稀土富集的右傾形式(LREE/HREE=5.67-8.37),缺少Eu異常,顯示活動大陸邊緣巖漿巖的稀土配分特征。日阿銅礦區(qū)成礦二長花崗斑巖巖石地球化學分析結果顯示為亞鋁質高鉀鈣堿性巖,為Ⅰ型花崗巖；微量元素原始地幔標準化蛛網(wǎng)圖上同樣富集大離子親石元素(LILE) Rb、Ba、Sr、 Th、U、K、Pb,虧損高場強元素(HFSE)Nb、Ta、Ti,稀土元素球粒隕石標準化圖表現(xiàn)為輕稀土富集的右傾形式(LREE/HREE=10.37-15.63), Eu負異常,同樣表現(xiàn)為典型的島弧巖漿作用的特征。 (2)尼雄鐵礦區(qū)成礦花崗閃長巖鋯石U-Pb LA-ICPMS測得巖體的206Pb/238U加權平均年齡為112.09±0.54Ma(MSWD=0.45),表明尼雄成礦巖體形成于早白堊世晚期；日阿銅礦區(qū)成礦二長花崗斑巖鋯石U-Pb LA-ICPMS測得巖體的206Pb/238U加權平均年齡為90.1±15Ma (MSWD=1.2),表明日阿成礦巖體形成于晚白堊世早期；由此可見,尼雄礦田鐵、銅礦化作用并非同時發(fā)生,而是存在早白堊世晚期(112.09Ma)的鐵礦化和晚白堊世早期(90.1Ma)的銅礦化兩個獨立的礦化階段。 (3)尼雄鐵礦區(qū)成礦巖體和日阿銅礦區(qū)成礦巖體的Sr-Nd-Pb同位素特征一方面顯示出富集地幔特征(EM11),另一方面又顯示出地殼組分對巖漿生成的重要影響。筆者對班公湖-怒江中特提斯洋和雅魯藏布江新特提斯洋演化歷史做了綜合分析,早白堊世晚期(尼雄鐵礦形成時：112.09±0.54Ma)以及晚白堊世早期(日阿銅礦形成時：90.1±1.5Ma)雅魯藏布江新特提斯洋殼正處于向北側岡底斯地塊之下俯沖的階段,符合尼雄鐵銅礦田的形成環(huán)境,由此作者得出尼雄鐵銅礦田是雅魯藏布江洋殼板塊向北側拉薩地塊之下俯沖的結果。 (4)尼雄鐵礦的源區(qū)富集主要是由板片派生流體對地幔楔交代改造的結果,而日阿銅礦的源區(qū)富集主要由板片熔體對地幔楔交代改造；地幔巖漿底侵引起下地殼物質部分熔融,兩種巖漿混合形成尼雄鐵銅礦田的成礦巖漿。尼雄鐵礦區(qū)的混源巖漿又經歷了鉀長石+斜長石以及副礦物褐簾石+獨居石的分離結晶作用；日阿銅礦區(qū)的混源巖漿經歷了鉀長石+斜長石(±黑云母)及副礦物磷灰石的分離結晶作用。
[Abstract]:The neixiong iron copper ore field is divided into 5 mining areas from the North West to the South East: the rolling iron mining area, the neixiong iron ore area, the Sha pine South iron mine, the mahastan iron ore area and the Japanese opiate ore area. This paper mainly analyzes the main element of the mineralization granodiorite and the two long granite porphyry in the neixiong iron copper mine, Tibet, in the minerogenetic granodiorite and the Japanese copper mine. The characteristics of elements, trace elements, REE and Sr-Nd-Pb isotopes have been determined and zircon LA-ICPMS U-Pb dating has been made.
(1) the geochemical analysis of the metallogenic granite diorite in the nxiong iron ore area shows that the series of potassium high potassium calcium alkaline rocks in the subaluminite belong to type I type granite, and the geochemical rock mass is enriched with large ion stone elements (LILE) Rb, Ba, Sr, Th, U, K, Pb, and the loss of high field and strong elements (HFSE) Nb, Ta, Ti, and typical island arc magmatism. The rare-earth chondrite standardization map shows the right leaning form of the enrichment of light rare earth (LREE/HREE=5.67-8.37), lacking the Eu anomaly, showing the REE distribution characteristics of the active continental margin magmatic rocks. The geochemical analysis of the two long granite porphyry rocks in the diuren copper mine area shows the subaluminous high potassium calc alkaline rock, which is type I granite. The microelement original mantle normalized arachnoid map also enriched the large ion stone elements (LILE) Rb, Ba, Sr, Th, U, K, Pb, the loss of high field and strong element (HFSE) Nb, Ta, Ti, and rare earth element chondrites, showing the right form of light rare earth enrichment, negative anomaly, and also a typical island arc MAGMATISM Characteristics.
(2) the 206Pb/238U weighted average age of the zircon U-Pb LA-ICPMS obtained from the granodiorite of the Nixiong iron ore area is 112.09 + 0.54Ma (MSWD=0.45), indicating that the neixiong metallogenic body was formed in the late Early Cretaceous, and the weighted average age of 206Pb/238U weighted 206Pb/238U of the zircon U-Pb LA-ICPMS obtained from the two long granite porphyry with the zircon U-Pb LA-ICPMS in the diuren copper mine area is 90.1 + 15Ma (MSWD=1.2) the A Cheng ore body formed in the early stage of the late Cretaceous. Thus, it can be seen that the iron and copper mineralization in the nsiong ore field did not occur simultaneously, but there were two independent mineralization stages in the late Early Cretaceous (112.09Ma) and the early Cretaceous (90.1Ma) copper mineralization.
(3) the Sr-Nd-Pb isotopic characteristics of the metallogenic rock mass of the Nixiong iron ore area and the ore-forming rock mass of the yalcu ore area show the characteristics of the enriched mantle (EM11) on the one hand, and on the other hand it shows the important influence of the crustal composition on the formation of magma. The author has made a comprehensive analysis of the evolution history of the Tethys and Yalu Zang Tethys in the and the Yalu and Yalu Zangbo River. In the late Early Cretaceous (112.09 + 0.54Ma) and the early Late Cretaceous (90.1 + 1.5Ma), the new Tethys oceanic crust in the Yarlung Zangbo River was under the subduction of the North Gangdise massif, which conforms to the formation environment of the Nixiong iron copper ore field, and the author concludes that the neixiong iron copper field is Yarlung Zangbo. The subduction of the Jiang Yang plate to the north side of the Lhasa block.
(4) the source area enrichment of Nixiong iron ore is mainly due to the transformation of mantle wedge metasomatism by plate derived fluids, and the source region enrichment of the Japanese opiate mainly consists of the metasomatism of the sheet melt to the mantle wedge; the mantle magma undertransgression causes the partial melting of the lower crust material, and the two magmas are mixed into the minerogenetic magma of the neixiong iron copper ore field. The mixed source magma also experienced the separation and crystallization of the potassium feldspar + plagioclase and the accessory mineral and the monazite, and the mixed magma of the diuren copper mine experienced the separation and crystallization of the potash feldspar + plagioclase (+ black mica) and the accessory mineral apatite.
【學位授予單位】：中國地質科學院
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P618.31;P618.41

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