本文選題：成巖-成礦年代學(xué) + 巖漿巖地球化學(xué)�。� 參考：《中國地質(zhì)大學(xué)》2017年博士論文

【摘要】：西藏尼木崗講銅鉬礦床大地構(gòu)造位于岡底斯陸緣火山-巖漿弧,成礦帶上位于岡底斯帶中段。礦床是由一系列產(chǎn)于二長花崗斑巖中的板狀次級銅鉬礦體組成。將崗講Cu-I礦體作為主要研究對象,對礦體形態(tài)變化特征、成巖成礦年代學(xué)、礦化富集規(guī)律及成礦機(jī)理等進(jìn)行重點(diǎn)研究,采用EH-4、高精度磁測技術(shù),結(jié)合已有遙感、土壤地球化學(xué)測量、激電測量數(shù)據(jù)的再處理,在崗講礦區(qū)及外圍開展找礦預(yù)測評價工作。通過研究,所獲得的主要成果及認(rèn)識如下:(1)崗講Cu-I礦體總體上由一系列近南北向、向西陡傾的板狀次級礦體組成,礦體品位、厚度定量分析表明,品位數(shù)值為單峰分布,北段礦體厚度大于南段礦體,品位略低于南段礦體,礦體垂向上具有“上銅下鉬”的分帶特點(diǎn)。(2)在充分分析崗講礦區(qū)主要侵入巖體的礦物組成、主量及微量元素基礎(chǔ)上,探討了區(qū)內(nèi)巖體的巖漿來源、形成的地質(zhì)背景,對巖體的含礦性進(jìn)行了評價。崗講侵入巖體屬于高鉀鈣堿性準(zhǔn)鋁質(zhì)-弱過鋁質(zhì)I-S過渡型花崗巖,相對偏向S型。各巖體微量元素普遍富集Rb、Th、U、Sr等大離子親石元素,相對虧損Nb、Ta、Zr等高場強(qiáng)元素,強(qiáng)烈虧損HREE、Y和Yb元素,稀土元素分配模式均表現(xiàn)為弱負(fù)銪異常的右傾斜輕稀土富集型,反映巖體之間相似的巖漿源區(qū),形成于印度-亞洲大陸碰撞后的應(yīng)力松弛伸展階段;從元素富集角度對各巖體與成礦關(guān)系進(jìn)行評價,認(rèn)為二長花崗斑巖是主要的成礦母巖;崗講礦區(qū)礦化斑巖與無礦化巖石微量元素對比研究表明,兩者具有相似的稀土、微量元素分配模式,礦化斑巖∑REE、LREE/HREE、(La/Yb)N隨著礦化強(qiáng)度的增強(qiáng)而表現(xiàn)為連續(xù)下降的趨勢,暗示原巖與礦化斑巖的內(nèi)在聯(lián)系,微量元素在熱液活動中呈比例遷出。(3)系統(tǒng)的成巖成礦年代學(xué)研究表明,崗講礦床二長花崗斑巖、花崗閃長斑巖和英云閃長玢巖LA-ICP-MS鋯石U-Pb加權(quán)平均年齡分別為16.6±0.3Ma(MSWD=0.94),16.1±0.2Ma(MSWD=1.07),14.4±0.4Ma(MSWD=1.12),結(jié)合野外地質(zhì)調(diào)查,厘定出崗講復(fù)式巖體侵入序列為含巨斑黑云二長花崗巖→二長花崗斑巖→流紋斑巖(深部定名為英云閃長玢巖)→安山玢巖;12件輝鉬礦樣品獲得的Re-Os同位素模式年齡加權(quán)平均值為13.4±0.1Ma(MSWD=0.65),等時線年齡為13.6±1.6Ma(MSWD=1.2),成礦時代為中新世,成巖成礦是一個連續(xù)的巖漿-熱液演化過程,形成于印度-亞洲大陸碰撞造山后的伸展階段。(4)構(gòu)建崗講Cu-I礦體原生暈分帶模式,垂向上表現(xiàn)為上部Mn、Co、Sb、Cu,中部Cu、Mo、Ni、Bi、W,下部為Zn、Ag、Pb,選取分帶指數(shù)值(Cu×Mo×Sb)D/(Pb×Zn×Ag)D作為構(gòu)建深部找礦預(yù)測模型的指標(biāo),建立了崗講礦床原生暈定量評價模型;圍巖蝕變分帶由內(nèi)而外依次為鉀-硅化帶、黃鐵絹英巖化帶、泥化帶和桻磐巖化帶,銅鉬礦化主要發(fā)生于鉀-硅化階段,黃鐵礦絹英巖化次之,多種蝕變帶疊加是成礦的有利部位;劃分礦床的形成階段,包括巖漿期、熱液期和表生期,巖漿期礦化規(guī)模大,但強(qiáng)度普遍偏低,熱液期和表生期對銅鉬礦化起到了明顯的改造富集、次生氧化淋濾作用;關(guān)于礦床的形成機(jī)理,認(rèn)為崗講礦床的形成是印度-亞洲大陸碰撞后伸展階段的構(gòu)造-巖漿-成礦事件之一,銅鉬礦化與中新世兩期含礦熱液活動息息相關(guān),含礦熱液沿巖體裂隙疊加貫入,多期次結(jié)晶分異最終形成品位較高的細(xì)脈-浸染狀銅鉬礦體;控礦構(gòu)造、剝蝕深度、蓋層性質(zhì)最終導(dǎo)致崗講與廳宮、白容、驅(qū)龍礦床在礦體品位、規(guī)模方面的差異。(5)在總結(jié)崗講礦區(qū)及外圍找礦標(biāo)志和找礦預(yù)測準(zhǔn)則基礎(chǔ)上,針對不同勘查區(qū)的研究程度、地質(zhì)特征選取不同的勘查技術(shù)手段進(jìn)行找礦預(yù)測,提出預(yù)測依據(jù)并對找礦遠(yuǎn)景區(qū)進(jìn)行圈定和評價,認(rèn)為崗講EH-4剖面西側(cè)的D1低阻異�？臻g上連續(xù)性好,為礦致異常的可能性較大;白容南部具有成為白容“第二條”東西向礦(化)帶的潛力;絨崗蒙西北部遙感蝕變異常明顯,野外踏勘發(fā)現(xiàn)規(guī)模較大的褐鐵礦化帶,顯示巨大的找礦前景;提出了白容北部尋找類似于湯巴拉矽卡巖型銅多金屬礦的新思路,試驗(yàn)性EH-4剖面和高精度磁測剖面反映的深部異常位置與構(gòu)建的白容-湯巴拉地質(zhì)推測模型計算的理論深度基本一致。圈定的找礦遠(yuǎn)景區(qū)有待更進(jìn)一步的勘查與研究工作,以期實(shí)現(xiàn)提質(zhì)增儲目的。
[Abstract]:In this paper , the major achievements and understandings are as follows : ( 1 ) The Cu - I ore body is composed of a series of plate - shaped secondary copper - molybdenum ore bodies , which are formed in two - length granodiorite porphyry . The main achievements and the recognition are as follows : ( 1 ) The Cu - I orebodies are mainly composed of a series of plate - shaped secondary ore bodies which are located in the south - to - north direction and the west - steep dip , and the ore grade and thickness quantitative analysis indicate that the grade values are single - peak distribution , and the ore body thickness of the north segment is larger than that of the south segment orebodies , and the ore body is slightly lower than that of the south segment orebodies . ( 2 ) Based on the analysis of the mineral composition , main quantity and trace elements of the main intrusive rock mass in the mining area , the ore - bearing properties of the rock mass are evaluated . The results show that the intrusive rock mass belongs to the high - field strength elements such as Rb , Th , U , Sr and so on , and the REE distribution patterns show that the two feldspar granite porphyry is the main ore - forming mother rock . The age - weighted average age of the two - long granite porphyry and the REE distribution pattern is 13.6 鹵 1.6Ma ( MSWD = 1.2 ) . ( 4 ) The primary halo zoning pattern of Cu - I orebodies is constructed . The vertical upward trend is the upper Mn , Co , Sb , Cu , Cu , Mo , Ni , Bi , W , the lower part is Zn , Ag and Pb . ( 5 ) On the basis of summarizing the geological prospecting and prospecting indicators and the prospecting prediction criterion , the authors put forward the basis for the prediction of prospecting for different exploration areas and the geological characteristics , and put forward the prediction basis and the potential for prospecting the remote areas . The southern part of Bairong has the potential to be the second " east - west mineral " zone of the EH - 4 section , and the experimental EH - 4 section and the high - precision magnetic survey section reflect the large scale of the brown iron ore belt . The exploration and research work is still to be further explored in the area of prospecting and exploration , with a view to achieving the purpose of upgrading the quality and storage .
【學(xué)位授予單位】：中國地質(zhì)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：P618.41;P618.65
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本文編號：2113455