本文選題：礦床地質(zhì)特征 + 巖石成因��； 參考：《中國(guó)地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：火麥地銅鉬礦床位于北祁連造山帶與西秦嶺造山帶的交接處,是西秦嶺北緣一個(gè)重要的斑巖型礦床。本文對(duì)火麥地銅鉬礦床地質(zhì)-地球化學(xué)特征進(jìn)行了詳細(xì)研究,查明了礦床空間展布特征和礦化-蝕變類型,厘清了成礦期的熱液脈體階段,查明了含礦斑巖巖石地球化學(xué)特征,測(cè)定了成巖-成礦時(shí)代,探討了含礦斑巖成因與成礦流體特征、成礦物質(zhì)來源及礦床成礦機(jī)制。1、礦床東、西區(qū)礦體產(chǎn)出部位不同。東區(qū)礦體主要產(chǎn)出于斑巖體外接觸帶蝕變石英砂巖地層中;西區(qū)礦體主要產(chǎn)出于凝灰質(zhì)角礫巖及外接觸帶附近地層中。以脈狀、扁豆?fàn)顬橹?總體走向310°~330°,傾向SW或NE,傾角在不同部位有所變化。鉀化帶、石英絹云母化帶、泥化帶、青盤巖化帶由內(nèi)而外呈面狀分布,礦化主要集中產(chǎn)出于石英絹云母化帶中。2、根據(jù)脈體切割關(guān)系及礦物共生組合可將巖漿-熱液網(wǎng)脈劃分為3大類,從早到晚分別為:粒狀石英-鉀長(zhǎng)石-黑云母-少量黃鐵礦脈(A脈);石英-黃銅礦-輝鉬礦-黃鐵礦-閃鋅礦脈(B脈);黃鐵礦-石英-少量黃銅礦脈(D脈)。3、H-O-S同位素測(cè)試結(jié)果顯示δ18OH2O值為8.6~13.6‰,δDH2O值為-50~-85‰,δ34S值為0.02‰~5.9‰,表明成礦流體主要來源于晚三疊世花崗質(zhì)巖漿在結(jié)晶分異過程中產(chǎn)生的巖漿熱液,后期有大氣降水加入。4、含礦石英閃長(zhǎng)斑巖、二長(zhǎng)斑巖、石英二長(zhǎng)斑巖均屬于高鉀鈣堿性的準(zhǔn)鋁質(zhì)-過鋁質(zhì)巖石系列,富集大離子親石元素,虧損Nb、Ta、Zr、Hf、Ti等高場(chǎng)強(qiáng)元素;εHf(t)值為 2.4~+6.1,TDM2=0.78 1.25 Ga;含礦斑巖的鋯石U-Pb年齡為215.0±5.8 Ma至226.6±6.2 Ma,代表了斑巖體的侵位年齡;礦石輝鉬礦Re-Os等時(shí)線年齡為208.5±1.3Ma,代表成礦年齡,成礦作用近于同時(shí)或者稍晚于巖體侵位年齡。結(jié)合西秦嶺造山帶大地構(gòu)造演化歷史研究,含礦斑巖地球化學(xué)特征、成巖成礦年齡表明:同碰撞向后碰撞構(gòu)造體制轉(zhuǎn)換(減壓增溫)時(shí)期古老下地殼部分熔融并有地幔物質(zhì)加入形成的巖漿攜帶成礦物質(zhì)沿?cái)嗔褞锨?冷凝分異出溶的成礦流體攜帶Cu、Mo、S等元素沿裂隙運(yùn)移、充填和交代圍巖形成該礦床。綜上所述,西秦嶺火麥地銅鉬礦床形成于印支期華北和華南板塊碰撞造山過程中,是典型的碰撞造山環(huán)境斑巖型礦床。
[Abstract]:Huomaidi Cu-Mo deposit is located at the junction of North Qilian orogenic belt and West Qinling orogenic belt and is an important porphyry deposit in the northern margin of West Qinling Mountains. In this paper, the geological and geochemical characteristics of Huomaidi copper-molybdenum deposit are studied in detail. The spatial distribution characteristics and mineralization-alteration types of the deposit are found out, the hydrothermal vein stage in the metallogenic period and the geochemical characteristics of the porphyry rocks in the ore-bearing period are clarified. The diagenetic and metallogenic ages are determined, and the genesis and ore-forming fluid characteristics of ore-bearing porphyry, the source of ore-forming material and the metallogenic mechanism of the deposit are discussed. The eastern ore body is mainly formed in the porphyry external contact zone alteration quartz sandstone strata and the western part is mainly produced in the tuffaceous breccia and the strata near the outer contact zone. The veins and lentils were dominant, and the general trend was 310 擄or 330 擄, which tended to SW or NE.The inclination changed in different parts. The kalitization zone, the quartz sericite zone, the mudding zone and the Qingpan lithochemical zone are distributed in a plane form from inside to outside. Mineralization is mainly concentrated in the quartz sericite belt. According to the vein cutting relationship and mineral symbiosis association, magma hydrothermal network veins can be divided into three categories. From early to late, they are: granular quartz-potassium feldspar-biotite-a small amount of pyrite vein (vein A); quartz-chalcopyrite-molybdenum-pyrite-sphalerite vein (B); pyrite-quartz-small amount of brass vein (D vein). The values of 未 18 O H 2O, 未 D H 2O and 未 34S are 8.6N 13.6 鈥，

本文編號(hào)：2083055