發(fā)布時間：2018-05-16 20:11

  本文選題：稀有金屬 + 地質(zhì)特征　； 參考：《蘭州大學》2016年博士論文

【摘要】：祁連山和北山地區(qū)分屬古特提斯和古亞洲大洋構(gòu)造域,在其構(gòu)造演化過程中形成了中國北方及中亞地區(qū)重要的巖漿-成礦帶而備受地質(zhì)學家的關(guān)注。近年來,甘肅省地質(zhì)調(diào)查院在祁連、北山等地區(qū)的地質(zhì)調(diào)查和研究工作顯示了以上地區(qū)具有形成大型、特大型稀有金屬礦的地質(zhì)條件,通過深入研究,有望取得找礦突破。本文以南祁連余石山鈮鉭礦、北山國寶山銣礦為研究對象,在系統(tǒng)收集前人研究成果的基礎(chǔ)上,通過野外地質(zhì)調(diào)查、室內(nèi)研究和測試分析等工作,基于現(xiàn)代成礦理論、巖石學和礦物學、地球化學和同位素年代學等,對以上兩處稀有金屬的成礦地質(zhì)背景、年代學、物質(zhì)來源、成礦規(guī)律等方面進行了研究。取得了如下成果和認識:1.通過野外地質(zhì)調(diào)查,詳細研究了余石山鈮鉭礦和國寶山銣礦的區(qū)域地質(zhì)、礦化類型、巖石學、礦物學、礦石學等特征。確定了余石山鈮鉭礦主要賦存于變粒巖中,國寶山銣礦主要賦存于含天河石花崗巖、花崗偉晶巖中。2.對余石山變粒巖、國寶山花崗巖類開展了鋯石U-Pb同位素定年研究。余石山變粒巖中鋯石有巖漿成因和變質(zhì)成因兩類,巖漿鋯石206Pb/238U年齡值在810±6Ma~854±7Ma之間,諧和年齡為829.4±2.7Ma,代表了巖漿侵入的時代;變質(zhì)成因鋯石206Pb/238U年齡值在768±8Ma~809±7Ma之間,諧和年齡為795±5.4Ma;代表了巖漿期后的熱事件。國寶山地區(qū)花崗片麻巖成巖年齡為1853±16Ma;(含天河石)二長花崗巖、花崗偉晶巖成巖年齡分別為427±8Ma、406±5Ma,揭示了巖漿從花崗巖漿演化到花崗偉晶巖持續(xù)時間達21Ma。3.運用巖石地球化學方法,對余石山變粒巖進行了原巖恢復(fù)。結(jié)果顯示原巖為正長巖,富硅、堿,貧鈣、鎂,高Rb、Th、Nb、Ta、Zr、Hf、Ga、Y,低Sr、Ba、Cr、Ni,以及明顯的負Eu異常和高的Ga/Al值(3~11)的特征,類似于A型花崗巖,形成于伸展的構(gòu)造背景,可能與Rodinia超大陸的裂解有關(guān)。國寶山花崗巖類屬于過鋁質(zhì)高鉀鈣堿性花崗巖,具有A型花崗巖的特征,稀土元素顯示弱的“四分組效應(yīng)”,指示了巖漿高度分異演化的特征,源于富含白云母的變質(zhì)泥巖類在正常地殼(約30km)深度下部分熔融。結(jié)合大地構(gòu)造背景,國寶山花崗片麻巖指示了古元古代晚期國寶山地區(qū)伸展構(gòu)造背景下的一次巖漿活動,巖漿經(jīng)歷了高度的演化;(含天河石)二長花崗巖和花崗偉晶巖形成于南天山洋盆的碰撞閉合后地殼伸展的構(gòu)造環(huán)境下,揭示了南天山洋于427 Ma之前閉合。4.電子探針結(jié)果顯示,余石山變粒巖中Nb和Ta主要賦存于金紅石、獨居石中,金紅石和獨居石地球化學特征表現(xiàn)為熱液變質(zhì)成因;國寶山銣礦Rb主要賦存于天河石中。5.余石山地區(qū)Nb、Ta的富集主要由金紅石引起,其富集機制也受控于金紅石的形成過程,變粒巖原巖(正長巖)在829.4Ma形成后,受795Ma左右發(fā)生的熱事件影響,與富H2O、F-等揮發(fā)分及K的巖漿期后熱液流體發(fā)生交代作用,隨著交代作用的進行,磷灰石、螢石等富F礦物的形成導(dǎo)致金紅石的生成,Nb、Ta伴隨金紅石的生成沉淀,聚集成礦。6.國寶山花崗巖源區(qū)中的白云母是成礦物質(zhì)Rb的主要來源,富含白云母的源巖脫水部分熔融產(chǎn)生高F、富Rb巖漿,巖漿的高度演化促使Rb進一步富集,主要富集機制是F的絡(luò)合作用,Rb與F絡(luò)合遷移至巖漿演化末期,最終隨溫度降低絡(luò)合物發(fā)生水解,F與Ca2+形成螢石,Rb進入長石形成礦化的含天河石花崗巖。7.余石山地區(qū)變粒巖及與其呈斷層接觸的大理巖是區(qū)域上尋找鈮鉭礦的主要標志;國寶山地區(qū)鈉長石化花崗巖、含天河石花崗巖(偉晶巖)是尋找銣礦的主要線索。
[Abstract]:The Qilian Mountains and the Beishan area belong to the Gut Tis and the paleo Asian oceanic domains. In the course of its tectonic evolution, the important magma metallogenic belt in northern and Central Asia has been formed and the geologists have attracted much attention. In recent years, the geological survey and research work of Gansu Geological Survey Institute in Qilian, Beishan and other areas showed the above area The geological conditions for the formation of large and large rare metal ores are expected to make a breakthrough in prospecting. This paper is based on the field geological survey, indoor research and test analysis on the basis of the systematic collection of previous research results, based on the modern study and the modern research results. Metallogenic theory, petrology and mineralogy, geochemistry and isotopic chronology have studied the metallogenic geological background, chronology, material source and metallogenic regularity of the two rare metals above. The following achievements and understanding are obtained: 1. the area of the Yu Shi Shan NB tantalum and rubidium in Baoshan is studied in detail through field geological investigation. The characteristics of geology, mineralization type, petrology, mineralogy, ore and so on. It is determined that the Yu Shi Shan niobium and tantalite ore mainly occurs in the granulite. The rubidium mine of the national treasure mountain is mainly located in the Tianhe stone granite. In the granitic pegmatite,.2. has carried out the zircon U-Pb isotopic study of the zircon, and the zircon in the granulite of the Yu stone mountain. There are two types of magma genesis and metamorphism, the 206Pb/238U age of magmatic zircon is between 810 + 6Ma~854 + 7Ma, and the harmonic age is 829.4 + 2.7Ma, representing the age of magma invasion; the 206Pb/238U age of the metamorphic zircons is between 768 + 8Ma~809 + 7Ma, and the harmonic age is 795 + 5.4Ma; it represents the heat event after the magma period. The age of gneiss rock formation is 1853 + 16Ma, (including Tianhe stone) two long granite, and the age of granite pegmatite diagenesis is 427 + 8Ma and 406 + 5Ma respectively. It reveals that the magma evolved from granitic pulp to granite pegmatite for 21Ma.3. using rock geochemistry method, and resumed the original rock of Yu Shi Shan granulite. The result showed that the original rock was syenite. The characteristics of rich silicon, alkali, poor calcium, magnesium, high Rb, Th, Nb, Ta, Zr, Hf, Ga, Y, low Sr, Ba, Cr, Ni, and obvious characteristics of negative anomalies and high values, formed in extensional tectonic setting, which may be related to the fragmentation of supercontinent. The rare earth element shows the weak "four grouping effect" indicating the characteristics of the magma height differentiation and evolution, which originated from the partial melting of metamorphic mudstones rich in Muscovite in the normal crust (about 30km). Combined with the tectonic setting, guomoshan granite gneiss indicates the extensional tectonic setting in the late proproterozoic Guobao mountain area. One magma activity, magma experienced a high degree of evolution, and (including Tianhe stone) two granites and granite pegmatite formed in the tectonic setting of the crust extension after the collision and closure of the South Tianshan ocean basin. The results of the closed.4. electron probe before the South Tianshan ocean in the southern Tianshan ocean revealed that Nb and Ta in the granulite of the Yu Shi Shan were mainly in rutile and solitary. In the stone, the geochemical characteristics of Jin Hongshi and monazite are characterized by hydrothermal metamorphism, and the Rb of the rubidium mine of the national treasure mountain is mainly located in the Nb in the.5. Yu Shi Shan area in Tianhe stone, and the enrichment of Ta is mainly caused by the formation of Jin Hongshi, and the metamorphic lithofacies (syenite), after the formation of 829.4Ma, is caused by the heat around 795Ma. The event is influenced by the metasomatism of the rich H2O, F- and K's post magmatic hydrothermal fluids. With the metasomatism, the formation of F minerals such as apatite and fluorite lead to the formation of rutile. Nb, Ta is accompanied by the formation and precipitation of rutile, and the Muscovite in the source area of the metallogenic.6. national treasure mountain granite is the main source of the mineral Rb. The source rocks of the source rock rich in Muscovite produce high F and rich Rb magma, and the high evolution of the magma leads to the further enrichment of Rb. The main enrichment mechanism is the complexation of F. Rb and F complex migrate to the end of the magma evolution, and the hydrolysis of the complex is reduced with the temperature, F and Ca2+ form the fluorite, and Rb enters the feldspar to form a mineralized containing Tianhe stone. The granulite in the.7. Yu Shi Shan area and the marble that contact with its faults are the main signs to find niobium and tantalite in the region, and the natriuretic granite and the Tianhe stone granite (pegmatite) are the main clues for the search for rubidium ore.
【學位授予單位】：蘭州大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：P618.2
，

本文編號：1898236