【作者】 吴自成；

【导师】 刘继顺；

【作者基本信息】 中南大学 ， 矿物学、矿床学、岩石学， 2012， 博士

【摘要】 哀牢山造山带是西南“三江”成矿带的重要单元,也是全球特提斯构造成矿域的一部分,是极具潜力的铜、金、银、钼、钨、锡多金属成矿带。笔者在校企合作项目的支持下,以“哀牢山造山带菲莫铜钼多金属矿矿床地球化学与成因探讨”为题,开展了博士论文工作。本文瞄准我国矿业和地质勘探行业发展的前沿,以区域成矿学和造山带成矿理论为指导,在对前人于哀牢山带勘查和研究成果充分借鉴和吸收的前提下,对菲莫铜钼多金属矿区及外围开展了广泛的野外地质调查和室内综合研究,取得了以下主要成果及认识：(1)菲莫铜钼多金属矿床位于哀牢山中深变质岩带内。区域性构造的演化,印支板块向扬子板块的俯冲,造就了一系列北西向地块及深大断裂。其中,红河断裂与哀牢山断裂共同决定了哀牢山中深变质岩带的发展、演化、空间展布及一系列与主构造线大致平行的断裂和褶皱的分布,同时控制着该区岩浆活动,从而也造成了哀牢山铜金为主的多金属成矿带与变基性岩及深部岩浆活动有关的铜金多金属矿床的成带分布。(2)哀牢山中深变质岩系是菲莫铜钼多金属矿床的含矿岩系,同时也是矿床成矿物质来源之一。矿床产在哀牢山中深变质岩中,含矿围岩主要为哀牢山群阿龙组菲莫段透辉石大理岩。哀牢山群由古元古代至新元古代1800-800Ma的构造岩片组成,其中主体岩石应形成于1600-1300Ma的构造变形与区域动力热流变质作用,在1000～800Ma经受了晋宁构造运动。哀牢山变质岩原岩恢复表明,其原岩主要为古元古代基性火山岩及沉积的灰岩、泥岩、白云质砂岩等。岩石地球化学特征表明,片岩类、麻粒岩等深色变质岩类富集大离子亲石元素K、Rb,明显亏损Nb、Ta、P和Ti等高场强元素,Th和Sr显示明显的负异常；同时表现出LREE富集右倾型配分模式,轻重稀土分异明显,轻稀土富集,铕异常不明显,铈负异常亦不明显,微量元素和稀土元素均表现出与基性岩及基性火山凝灰岩相似的特征。大理岩类富集Rb、U,明显亏损Nb、Ta、P和Ti, Ba和Sr显示明显的负异常,LREE为富集右倾型配分模式,轻稀土分异明显且富集,铕异常明显,表现出与白云岩、灰岩等碳酸盐岩相似的特征。(3)首次对研究区大皮甲小岩体进行了岩石地球化学研究,其岩性主要为二云二长花岗岩。w (SiOz)平均为72.42%,A/CNK(分子比)>1.1(平均1.17),K20/Na2O平均为2.18,里特曼指数(σ)为1.76-4.19(平均3.02),分异指数(DI)为90～92,Σ REE在103.34×10-6-247.39×10-6之间,ΣLREE/ΣHREE在1.16-7.45之间,具弱Eu正异常,在原始地幔标准化蛛网图上显示出Nb、P、Ti负异常和K、Rb、Ba、Th、U正异常,具明显的分异结晶作用特征。岩体的地球化学特征属于高硅、过铝、钙碱性(略偏碱钙性)花岗岩,具有壳幔混源型花岗岩的特征。经多种相关图解判别,大皮甲岩体为碰撞造山花岗岩类,形成于同碰撞及后造山的构造环境。岩体形成年龄大约为57.72Ma,其时正好发生喜山期大规模陆内变形过程中的大规模成岩、成矿作用。岩体提供了部分成矿物质,尤其是钼。(4)首次对菲莫铜钼多金属矿床辉钼矿进行了Re-Os同位素精确测年,获得辉钼矿Re-Os同位素模式年龄为47.81±0.71Ma,与哀牢山铜金多金属成矿带镇沅、墨江、大坪大型金矿大约在同时期形成(均为50Ma±)。彼时喜玛拉雅运动的隆升挤压、花岗岩侵入导致哀牢山造山带大规模的构造-岩浆-热事件,在热动力的驱动下,成矿流体、挥发组分的共同作用下,使成矿元素大量聚集,造成该时期成矿作用大爆发,形成诸多大、中型铜、金多金属矿床。菲莫铜钼多金属矿床形成的年代格架大致为：在古元古代(1800～1600Ma)形成基性火山岩为主的含铜原生矿化层,后经中-新元古代(1600～900Ma)变质作用及晋宁运动(900～800Ma)对原生矿进行了初步改造富集,又经历了印支运动(260Ma)走滑-推覆作用引起的糜棱岩化对铜多金属矿的剪切改造及燕山运动(160～80Ma)花岗岩侵入对矿床的进一步热改造,而后喜玛拉雅运动(65～10Ma)的隆升挤压、花岗岩侵入形成的大规模的构造-岩浆-热事件对矿床进行了颠覆性的叠加改造,同时也带来了新的成矿物质,成为主成矿期。(5)首次对菲莫铜钼多金属矿床进行了成矿物质来源、成矿流体来源、成矿温度、压力及矿床成因研究。矿床地球化学研究显示,矿区H、O、S、Pb同位素和稀土元素、微量元素等地球化学特征表明成矿物质主要来源于深部地幔或下地壳古老基底,后混入部分上地壳物质；含矿流体以原生岩浆水为主,又加入部分大气降水和变质水。流体包裹体测温显示矿床成矿流体为一种低盐度、低密度、高温、高压的深源流体。结合矿床产出构造环境、围岩蚀变类型、控矿要素和同位素特征等分析,认为菲莫铜钼多金属矿床赋矿地层中深色中深变质岩系提供了部分成矿物质,另外部分成矿物质来自于深部岩浆及岩浆途经的围岩。矿床成因研究结果显示,断裂破碎带、岩浆上涌通道有利于深部成矿物质的上侵；喜山期花岗岩侵入导致了矿床的最终定位,岩浆侵入所带来的岩浆热液汇合加热的地下水溶液形成成矿热液。矿床成因类型为沉积-变质-岩浆热液叠加改造型铜钼多金属矿床。(6)通过研究和总结菲莫铜钼多金属矿床的地质地球化学特征和成矿规律,阐述了铜钼多金属矿体与哀牢山变质岩系及大皮甲花岗岩体的时空关系和成因联系。基于矿床Cu、Mo、Au、Ag的成因、时空分布规律,建立了菲莫铜钼多金属矿床的成矿模式,同时总结出了构造、岩性、岩浆岩、矿化蚀变、航磁、地球物理和地球化学异常等7项关键找矿标志。根据含矿花岗岩脉,花岗岩体矿化露头,推测矿区深部很有可能存在规模较大的斑岩型和接触交代型铜钼多金属矿床。更多还原

【Abstract】 Ailaoshan orogenic belt is the important composition unit of the southwest "Sanjiang" metallogenic belt, part of the Tethyan metallogenic domain. It is also the great potential polymetallic metallogenic belt of copper, gold, molybdenum, tungsten and tin.Supported by the cooperation of school and enterprise, the author has made the documentary on the subject of "discussion on the geochemistry and genesis characteristics of Feimo Cu-Mo polymetalic deposit in Ailaoshan orogenic belt". Guided by regional metallogeny and the metallogenic theory of orogen belts, subject to the absorption and drawing upon the former achievements on the Ailaoshan exploration and research, doing widely field geological investigation and indoor synthetic analysis at the mining districts and its surrounding area, this article was at the forefront of the geostatistics and geological exploration in our country. Achievements obtained are as follows:(1)Feimo Cu-Mo polymetalic deposits are located in the medium-deep dark colored metamorphic rock of Ailaoshan belt. The evolution progress of tectonic and the Yangtze plate triggered toward by the Indian Ocean plate make a series of northwest blocks and discordogenic fault; Honghe fault and Ailaoshan fault which determined the development, evolution and spatial distribution of the medium-deep Ailaoshan metamorphic rock belt, the distribution pattern of the series of fracture and fold structure that paralleled to the main structure line, and the magmatic action of this area; all of those are finally formed the Ailaoshan polymetallic metallogenic belt and the Cu-polymetalic metallogenic belt in connection with metabasite and deep igneous activity.(2) The medium-deep metamorphic rock in Ailaoshan belt is the ore-bearing rock series of Feimo Cu-Mo polymetalic deposit, and it is also the ore-forming material source of the deposit. The deposit is hosted in the medium-deep dark colored metamorphic rock of Ailaoshan belt. The ore-bearing wellrock are diopside marble in Feimo section Along Fm Ailaoshan group. Ailaoshan group composed chiefly of1800-800Ma Paleoproterozoic to Neoproterozoic tectonic microlithon, and its host rock should be formed in1600～1300Ma by the structural deformation and dynamothermal metamorphism,1000～800Ma by Jinning movement. The reconstruction of metamorphic rocks protoliths in Ailaoshan showing that its protoliths was basic volcanic rock and sediment limestone, mudstone, dolomitic sandstone in early proterozoic. Geochemical characteristics showing that the dark colored metamorphite schists, granulites are characterized by obvious macroion lithophile K, Rb enrichment, significantly, depletion of HFSE Nb, Ta, P and Ti. Th and Sr distinctly negative anomaly; chondrite-normalized patterns are showing minor fractionation with flat to strongly HREE-depleted patterns, characterized by obvious fractionation of REE, with not obvious Eu and Ce anomalies; trace elements and rare earth elements suggest that they are having the similar characteristics with basic rock and basic volcanic tuff. Marble are characterized by obvious Rb, U enrichment, significantly depletion of Nb, Ta, P and Ti, strong negative Ba and Sr anomalies; chondrite-normalized patterns showing minor fractionation with flat to strongly HREE-depleted patterns, characterized by obvious fractionation of REE, with obvious Eu anomalies; trace elements and rare earth elements suggest that they are having the similar characteristics with carbonatite like dolostone and limestone.(3)Dapijia small intrusions was first researched its rock geochemical characteristics, its lithology are dimicaceous monzonitic granite. The average w (SiO2) is72.42%, A/CNK (molecular ratio)>1.1(1.17on average), the average K2O/Na2O is2.18, the rittman index (σ) is1.76～4.19(3.02on average), the differentiation index (DI) is90～92, ΣREE is between103.34×10-6and247.39×10-6, ΣLREE/ΣHREE is between1.16and7.45, obvious Eu positive anomalies; in the curves of the trace element distribution patterns normalized by the primitive mantle, they are K, Rb, Ba, U-rich and Nb, P, Ti-depletion, have the characterics of crystallization differentiation. Geochemical characteristics of rock-body have similarity with crust-mantle mixed type of magma, high silica, excess aluminum, and calc-alkaline granite. Various diagrams for discrimination of protolith reveal that Dapijia rock-body was collisional orogeny granite, which were formed in collide and post_orogenic extensional structural environment. The ore-forming age of the rock-body is57.72Ma; which is slmilar to the age of large-scale Diagenesis-mineralization in Himalayan Epoch with large-scale inner deforming. Part of the metallogenic materials are supplied by the rock-body, especially Mo.(4)Feimo Cu-Mo polymetalic deposit was first researched its Re-Os isotopic data of molybdenite, attained the age of47.81+0.71Ma, which is slmilar to the age of Zhenyuan, Mojiang, Daping gold deposits in Alaoshan Cu-polymetalic(50Ma±on average). Bulge-extrusion in Himalayan movement, large scale tectono-magmatic thermal event by granite intrusion in Ailaoshan, actived by the magmatic explosion, ore-forming fluid and the volatile component, The act of gathering in large numbers of metallogenic element, and their cosmical mineralization interaction in mineralization period, forming the large-middle Cu-Au polymetalic deposit. The time framework of Feimo Cu-Mo polymetalic deposit is that:the original mineralized layers are the basic volcanic rock (the original mineralized layers that contains copper) which were formed approximately in Proterozoic era (1800-1600Ma), and the concentration, reformation by the action of the metamorphism in Mesoproterozoic-Neoproterozoic (1600-900Ma) then the Jinning movement (900-800Ma), and the reforming in Cu-polymetalic deposit by the strike slipping and overthrusting mylonitization in the Indosinian movement (260Ma), the modification of thermal fluid by the granite intrusive in Yanshan movement (160-80Ma), the bulging-extrusion in Himlayan movement (65-1OMa), and the subversive acts of the large scale tectono-magmatic thermal event by granite intrusion bring the new metallogenic material and become the main mineralizing stages of the deposit.(5) Research on the geochemical characteristic of the deposit showing that, the isotopic data of elements H, O, S, Pb and rare-earth element, trace element are all reach an agreement that the mineralizing matter of the deposit are mainly from deep, the aquatic medium of the metallogenic fluids is magmatic water meteoric on the supplying. Combine with the tectonic setting of the deposit, the types of the wall rock alteration, the ore-controlling factors and the characteristics of isotope, they are showing that the dark-colored metamorphic series in the host strata of the Feimo Cu-Mo polymetalic deposit provided with part of the metallogenic material, the hypomagma, the continental basements of the convectional circulation and the wallrock by igneous intrusion provided with another part of the metallogenic material. Research on the genetic type of the deposit is showing that the discordogenic fault and the path of magma are conducive to the deep material upwelling; the granite intrusive in Himalayan Epoch is the fixation phase of the deposit, the mineralizing fluid are magmatic hydrothermal by granite intrusive which mixed with heated the ground water; the metallogenic material are composed of the deep material and the materials of the process of layer extracting by the hot water. The genetic type of the deposit belongs to sedimentary-metamorphic-superposition of magmatic hydrothermalism reworked Cu-Mo polymetalic deposit.(6) The article summarized the geological and geochemical characteristic of the Feimo Cu-Mo polymetalic deposit and the regularity of ore formation; illustrated the time-space relationship and the genetic relation of the Cu-Mo polymetalic orebody, Ailaoshan metamorphic series and Dapijia granite body; constructed the metallogenic model of Feimo Cu-Mo polymetalic deposit on the genetic type and the time-space distribution pattern of the deposit Cu、Mo、Au、Ag; and summarized the seven critical indicators for deposit, structure, lithology, magmatite, alteration, aeromagnetic survey, physical geography and geochemical anomaly. By the mineral-bearing granite vein, exposed mineralization in granite body, we conclude that the deep level of ore deposit has a good prospect for large scale of porphyry type and contact metasomatic Cu-Mo polymetalic deposit.更多还原