本文選題：紅石山鎂鐵-超鎂鐵質(zhì)巖　切入點(diǎn)：銅鎳礦床　出處：《中國(guó)地質(zhì)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：新疆北山西段紅石山地區(qū)發(fā)育了一系列二疊紀(jì)鎂鐵-超鎂鐵質(zhì)巖和紅石山、紅鎳山鎳礦床及一些礦化異常。礦化多以稀疏浸染狀為主,品位較低,近年來找礦工作未有太大突破。此外該地區(qū)成巖動(dòng)力學(xué)背景存在爭(zhēng)議,巖漿起源與演化研究不足,硫化物熔離作用未有系統(tǒng)研究,礦化規(guī)律總結(jié)薄弱。本論文旨在詳細(xì)野外地質(zhì)調(diào)查的基礎(chǔ)上,通過系統(tǒng)巖石學(xué)、礦物學(xué)、年代學(xué)和地球化學(xué)手段深刻認(rèn)識(shí)成巖動(dòng)力學(xué)背景和成巖成礦作用,總結(jié)礦化規(guī)律,建立成礦模式,提高找礦理論上認(rèn)識(shí),為下一步勘探工作提供科學(xué)依據(jù)。鎂鐵-超鎂鐵質(zhì)巖沿著紅柳河-依格孜塔格深大斷裂南緣成群成帶產(chǎn)出,大多侵位于下石炭統(tǒng)紅柳園組和下寒武統(tǒng)雙鷹山組一套變質(zhì)巖中。主要巖石類型有蘇長(zhǎng)巖、輝長(zhǎng)巖、橄欖輝長(zhǎng)巖、橄長(zhǎng)巖、單輝橄欖巖、輝橄巖、純橄巖等。含礦晚期輝橄巖和純橄巖相發(fā)育在巖體中心部位偏下。巖石低Si高M(jìn)g,低堿貧Ca,多屬亞堿性、拉斑玄武系列,整體稀土含量偏低,輕重稀土分異不太明顯。巖石富集Zr、Hf、Th、U等高場(chǎng)強(qiáng)元素,虧損Rb,Nb,Ta,同時(shí)具明顯的Pb,Sr正異常。PGE含量主要受控于巖漿作用,與后期熱液事件關(guān)系不大。成巖過程以結(jié)晶分異為主,同時(shí)發(fā)生了明顯的地殼混染,后期遭受了強(qiáng)烈的蝕變和風(fēng)化作用。橄欖石主要為貴橄欖石,最高Fo值90.3。單斜輝石主要為普通輝石和透輝石,斜方輝石主要為斜頑輝石。橄欖輝長(zhǎng)巖和橄長(zhǎng)巖中的早于硅酸鹽礦物結(jié)晶,包裹于橄欖石和輝石中的鉻鐵礦顆粒受后期改造最微弱,最能代表原始鉻鐵礦,因而可用來反演母巖漿性質(zhì)。鎂鐵質(zhì)巖漿作用有兩期:大部分巖體侵位于早二疊世(271-284Ma);蠶頭山巖體、旋窩嶺巖體、羅東鎂鐵質(zhì)巖脈侵位于晚二疊世(261-266Ma)。相關(guān)的中酸性巖侵位于早二疊世(271-280Ma)。早二疊世鎂鐵質(zhì)巖的Rb-Sr同位素組成較寬,(87Sr/86Sr)i為0.702949-0.712714,初始Nd較低且集中(143Nd/144Nd)i=0.512219-0.512843,εNd(t)=-1.29-11.2。鋯石176Hf/177Hf=0.28274-0.28282,計(jì)算的εHf(t)=4.9-7.8,一階段模式年齡TDM1=618-742Ma。鎂鐵質(zhì)巖地幔源區(qū)為虧損地幔,同時(shí)受到了EMII改造。北山地幔源區(qū)受改造影響較東天山、中天山地區(qū)明顯。早二疊世鎂鐵質(zhì)巖母巖漿起源于受俯沖流體交代改造的虧損地幔在相對(duì)淺的深度發(fā)生16.5-17.0%的部分熔融,其具高鎂(14.5%wt.%MgO)、高溫(1368℃)、含水特征。晚二疊世巖石母巖漿具類似性質(zhì),只是源區(qū)受改造程度更高,熔融程度稍低(14.3%)。綜合鎂鐵質(zhì)侵入巖、玄武巖、中酸性巖石的巖石學(xué)、礦物學(xué)、年代學(xué)和地球化學(xué)特征及與東天山、塔里木地區(qū)相關(guān)巖石的對(duì)比,北山地區(qū)早二疊世大規(guī)模鎂鐵-超鎂鐵質(zhì)巖漿作用并非形成于島弧環(huán)境,亦非地幔柱成因,而更可能是后碰撞伸展環(huán)境下板片斷裂造成的軟流圈地幔上涌。部分巖漿上侵至地表形成鈣堿性玄武巖、英安巖等火山巖組合。此外幔源巖漿與新生地殼脫水熔融巖漿的混合,同時(shí)裹入古老地殼物質(zhì),除了形成A型花崗巖外,還形成了I型、S型花崗巖組合。鎂鐵-超鎂鐵質(zhì)巖漿作用一直持續(xù)到晚二疊世。礦體主要呈懸浮狀產(chǎn)于輝橄巖底部。3D磁法反演顯示巖漿通道方向?yàn)槟衔魃畈恐帘睎|淺部。Se、Te等中低溫元素與礦體產(chǎn)出吻合可能反映了低溫?zé)嵋鹤饔脤?duì)礦化富集有一定貢獻(xiàn)。珠滴狀硫化物顯示巖漿演化過程中發(fā)生了硫化物熔離,Cu/Zr比值、PGE含量和橄欖石成分模擬表明橄欖石發(fā)生4%結(jié)晶時(shí)硫已達(dá)飽和并發(fā)生熔離,熔離程度為0.015-0.02%,形成低品位浸染狀礦化。坡北巖帶在橄欖石結(jié)晶之前即發(fā)生硫化物熔離,且熔離一直持續(xù)到橄欖石結(jié)晶過程中,分別形成高品位貫入式脈狀礦化和低品位浸染狀礦化。硅質(zhì)鈣質(zhì)地層混染有利于硫化物熔離,但貢獻(xiàn)有限。巖漿早期鉻鐵礦、橄欖石的結(jié)晶導(dǎo)致巖漿體系中FeO含量和硫溶解度的降低,促使硫飽和并發(fā)生熔離。綜合鎂鐵質(zhì)巖石產(chǎn)出構(gòu)造背景、巖漿源區(qū)及性質(zhì)、硫化物熔離及巖漿侵位序次,北山巖漿型銅鎳礦床的成礦模式為“深部熔離+就地熔離多期次脈動(dòng)成礦”。深大斷裂與次級(jí)斷裂的交匯部位是尋找鎂鐵質(zhì)巖的構(gòu)造條件。巖相分異明顯,含有輝橄巖等超鎂鐵質(zhì)巖相,其橄欖石中Ni含量不能太高,這些地質(zhì)信息在找礦勘探中應(yīng)該重點(diǎn)關(guān)注。拉斑玄武質(zhì)母巖漿、巖體低Ti高M(jìn)g、高m/s和m/f、母巖漿MgO含量大于11.5%、部分熔融程度不低于12-15%、固結(jié)指數(shù)SI大于40、TiO2含量小于1%,均是有利含礦的地球化學(xué)指標(biāo)。
[Abstract]:The western part of Xinjiang Beishan Hongshishan area developed a series of Permian mafic ultramafic rocks and red hill, red hill nickel nickel deposit and mineralization anomalies. Mineralization in sparse disseminated, low grade ore prospecting work in recent years not much breakthrough. In addition the diagenetic dynamic controversial background, the origin and evolution of magma, the sulfide liquation mineralization rules no system research, this paper aims to summarize the weak. Based on detailed field geological survey, through systematic mineralogy, petrology, geochronology and geochemistry means a profound understanding of diagenetic dynamics background and mineralization, summed up the mineralization regularity and metallogenic mode is established, improve prospecting theory knowledge, and provide scientific basis for the next exploration. Mafic ultramafic rocks along the southern margin of the Hongliuhe - in lattice MUZTAG deep faults in groups with output, most invasion Located in the lower Carboniferous hongliuyuan formation and lower Cambrian metamorphic rocks in a group of Eagle mountain. The main rock types include Su Changyan, gabbro, olivine gabbro, troctolite, peridotite, harzburgite, dunite. Ore late harzburgite and dunite facies developed in the rock mass center a partial rock. Low Si and high Mg, low alkali and poor Ca, belong to sub alkaline and tholeiitic series, the overall low content of rare earth elements, REE fractionation is not obvious. The enrichment of Zr, Hf, Th, U and other high field strength elements, the loss of Rb, Nb, Ta, at the same time with obvious Pb the content of.PGE, Sr positive anomaly is mainly controlled by magma, and it is a little late hydrothermal event. The diagenetic process dominated by crystallization differentiation, and has significant crustal contamination, later suffered a strong alteration and weathering. Olivine is mainly of olivine, clinopyroxene 90.3. the highest Fo value is mainly ordinary augite and diopside, trapezius Pyroxene is mainly clinoenstatite. Olive gabbro and troctolite in early crystallization in silicate minerals, chromite particles in olivine and pyroxene in the post transformation of the weak, the most representative of the original chromite, and thus can be used to inverse the parent magma properties. Mafic magmatism have two stages: most rock mass emplaced in the early Permian (271-284Ma); silkworm head mountain rock xuanwoling mafic ultramafic intrusion, Luo Dongmei iron dikes emplaced in the Late Permian (261-266Ma). In the acidic rock erosion related in Early Permian (271-280Ma). Early Permian mafic rock Rb-Sr isotopic composition of wide (87Sr/86Sr) I 0.702949-0.712714, initial Nd low concentration (143Nd/144Nd) and i=0.512219-0.512843 Nd (T) =-1.29-11.2., epsilon epsilon zircon 176Hf/177Hf=0.28274-0.28282, calculated by Hf (T) =4.9-7.8, a TDM1=618-742Ma. model age mafic rock mantle depleted mantle, at the same time By the EMII transformation. The mantle source region of Beishan by transformation influence in eastern Tianshan Mountains, in the Tianshan area is obvious. The partial melting of the early Permian mafic rock magma origin 16.5-17.0% occurred at a relatively shallow depth by subduction fluids transformation of the depleted mantle, with its high magnesium (14.5%wt.% MgO), high temperature (1368 DEG C). Water features. Late Permian rock magma with similar properties, but the source region by transformation of higher degree, degree of melting is slightly lower (14.3%). The comprehensive mafic intrusive rocks, basalt, petrology, mineralogy of acid rocks, geochronology and geochemistry and related rocks in East Tianshan, comparison of Tarim area, Beishan area the large-scale Early Permian mafic ultramafic magmatism is not formed in an island arc environment, nor the causes of mantle plume, but more likely after the collision of asthenospheric mantle stretching plate fracture environment caused by the upwelling of magma. The intrusion to the surface formation of calc alkaline basalt, dacite and volcano rock combination. In addition mixed mantle derived magma and crustal new dehydration melting magma, and wrapped in ancient crust, in addition to the formation of A type granites, formed I type, S type granite assemblage. Mafic ultramafic magmatism has been until the Late Permian. The ore body mainly is suspended from harzburgite at the bottom of the.3D magnetic inversion shows the direction for the magma channel to the North East Nancy deep shallow.Se, Te in the low temperature elements and orebody may reflect a consistent low temperature hydrothermal mineralization has a certain effect on the bead sulfide display contribution. In the process of magmatic evolution occurred in sulfide segregation, Cu/Zr ratio, PGE content and composition of simulation show that olivine occurs 4% olivine crystallization of sulfur has reached saturation and segregation, segregation degree of 0.015-0.02%, the formation of low-grade disseminated mineralization slope. The North rock belt of sulfide segregation that occurs in olivine crystals before and liquation until the olivine crystallization process, the formation of high grade and low grade penetration mineralization disseminated mineralization respectively. Siliceous contamination is conducive to the formation of calcium sulfide segregation, but limited contribution. Early magmatic chromite, olivine crystallization leads to the decrease of the content of FeO and sulfur solubility in the magmatic system, the sulfur saturation and segregation. The comprehensive mafic rocks tectonic background, magma source and nature, sulfide segregation and magmatic emplacement sequence, metallogenic model of Beishan magmatic copper nickel ore bed "deep liquation + in-situ liquation and multi period" the intersection of pulsating mineralization. Deep faults and secondary faults are looking for structural conditions of mafic rocks. The lithofacies are distinct, contains harzburgite and ultramafic lithofacies, the olivine Ni content can not be too high, the geological Information should be paid attention to in prospecting and exploration. The Ti content of the Mg is high, and the content of MgO is more than 11.5%. The partial melting degree is less than 12-15%, the consolidation index is more than 40, and the TiO2 content is less than 1%, which is the geochemical indicator of favorable ore content. The rock mass is low m/s, m/f and high.

【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：P611;P587
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本文編號(hào)：1637137