本文關(guān)鍵詞： 白山斑巖型鉬礦 地球化學(xué) SIMS鋯石U-Pb定年 鋯石Hf同位素 成礦機制　出處：《中國地質(zhì)大學(xué)(北京)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：白山鉬礦床位于東天山康古爾-黃山韌性剪切帶三岔口-白山斑巖銅鉬礦帶中,賦礦地層為下石炭統(tǒng)干墩組,成礦巖體為晚三疊世花崗斑巖。本文以白山鉬礦為研究對象,對白山鉬礦區(qū)深部巖體進行了詳細的巖相學(xué)、巖石地球化學(xué)、SIMS鋯石U-Pb定年以及鋯石原位Hf同位素分析,旨在確定成礦巖體的巖石成因類型、巖體形成時代以及巖漿源區(qū)特征,進而分析成礦動力學(xué)背景以及礦床形成機制。地球化學(xué)特征顯示,白山鉬礦區(qū)深部花崗斑巖富SiO2、Al2O3和堿質(zhì),MgO和地幔相容元素Cr、Ni含量低；明顯富集Rb、Ba、Th和U等大離子親石元素,虧損Nb、Ta、Zr和Hf等高場強元素。屬高鉀鈣堿性、準鋁質(zhì)到過鋁質(zhì)的Ⅰ型花崗巖,并具有埃達克巖的地球化學(xué)特征。同時,白山鉬礦區(qū)深部花崗斑巖鋯石εHf(t)為正值(+8.3～+12),地殼模式年齡(TDMC)為556～758Ma。以上特征顯示白山鉬礦區(qū)深部花崗斑巖由增厚的新生下地殼部分熔融形成。白山鉬礦區(qū)深部斑巖體SIMS鋯石U-Pb年齡為229.7±3.2Ma,前人獲得的輝鉬礦Re-Os等時線年齡為225～229Ma,成礦年齡與成巖年齡基本一致。結(jié)合前人研究成果,可以確定白山鉬礦形成于晚三疊世板內(nèi)伸展環(huán)境。晚石炭世古天山洋盆閉合之后,東天山地區(qū)進入碰撞-后碰撞階段。晚三疊世在板內(nèi)伸展環(huán)境的背景下,新生下地殼因自身增厚或受到幔源底侵巖漿熱量的影響,熔融產(chǎn)生埃達克質(zhì)巖漿,熔融過程中析出的金屬及揮發(fā)分隨埃達克質(zhì)巖漿一起向上運移,埃達克質(zhì)巖漿上侵到達地殼淺部,隨著溫度、壓力的降低,成礦金屬和流體從巖漿中大量析出,形成含礦熱液。含礦熱液在巖體上部的圍巖中沿裂隙充填、交代,最終形成輝鉬礦沉淀。
[Abstract]:The Baishan molybdenum deposit is located in the Sanchaikou-Baishan porphyry copper-molybdenum ore belt in the Kangguer-Huangshan ductile shear zone of East Tianshan. The ore-bearing strata are the Dendun formation of Lower Carboniferous and the ore-forming rock mass is late Triassic granitic porphyry. Detailed lithofacies, geochemistry and zircon U-Pb dating of zircon and in situ HF isotopic analysis of zircon in Baishan molybdenum ore area were carried out in order to determine the petrogenetic type, age of formation and characteristics of magmatic source. The geochemical characteristics of the deep granitic porphyry in Baishan molybdenum ore area show that the deep granitic porphyry is rich in Sio _ 2-Al _ 2O _ 3 and alkaline MgO and the mantle compatible element Cr-Ni, and is obviously enriched in large ion lithophile elements, such as RB _ (b) Ban _ (Th) and U, and so on. Depleted high field strength elements, such as NB, Tazn, Zr and HF, belong to high-potassium calc-alkaline, quasi-aluminous to peraluminous type I granites, and have geochemical characteristics of adakite. The zircon 蔚 Hft of the deep granitic porphyry in the Baishan molybdenum ore area is positive (8.312g, the crustal model age (TDMCT) is 556N758Ma. the above characteristics indicate that the deep granitic porphyry in the Baishan molybdenum ore area is formed by thickening partial melting of the lower crust.) the deep porphyry of the Baishan molybdenum ore area is formed by the partial melting of the thickened lower crust. The SIMS zircon U-Pb age is 229.7 鹵3.2Ma. the Re-Os isochron age of molybdenite obtained by predecessors is 225U 229Ma.The metallogenic age is basically consistent with that of diagenesis. It can be determined that the Baishan molybdenum deposit was formed in the late Triassic intraplate extensional environment. After the late Carboniferous Paleo-Tianshan ocean basin was closed, the East Tianshan area entered the collision-post-collision stage. Due to the thickening of the new lower crust or the influence of the heat of the mantle underplating magma, the melting produces the adakitic magma, and the metals and volatile matter precipitated during the melting process migrate upward along with the adakitic magma. With the decrease of temperature and pressure, the ore-forming metals and fluids are precipitated from the magma in large quantities to form ore-bearing hydrothermal solution, which is filled along the fissure in the surrounding rock of the upper part of the rock mass. Molybdenum deposits are formed eventually.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P618.65

【參考文獻】

相關(guān)期刊論文 前1條

1 PATERNO R. CASTILLO;;AN OVERVIEW OF ADAKITE PETROGENESIS[J];Chinese Science Bulletin;2006年03期

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本文編號：1536438