【作者】 于蕾；

【导师】 王训练； 张道红；

【作者基本信息】 中国地质大学(北京) ， 古生物学与地层学， 2012， 博士

【摘要】 铝土矿为云南优势矿种，主要分布于滇东南地区。本文运用地层学、岩相学、地球化学分析等方法手段，综合研究了滇东南地区沉积型铝土矿主要成矿期—晚二叠世吴家坪早期沉积古地理环境及其与铝土矿成矿作用的关系、含铝岩系特征、地球化学特征和控矿因素等，阐述了矿床成矿物质来源，总结了成矿规律，建立了找矿标志，分析探讨了矿床成因，进行了成矿远景预测。研究区沉积型铝土矿床主要为一水硬铝石型铝土矿，含矿岩系为上二叠统吴家坪阶下段。矿石主要组成矿物为一水硬铝石，其次是高岭石、锐钛矿、针铁矿等。一水硬铝石呈现出多种结晶形态及复杂的赋存状态，其嵌布特征主要有5种：呈自形、半自形粒状不均匀地嵌布在脉石矿物中；呈豆状、土豆状、豆鲕状产出；呈隐晶质、微晶集合体或呈极不规则的粒状、微粒状产出；呈脉状、骸晶状产出；一水硬铝石与铝凝胶或脉石矿物的集合体呈环带状或同心圆状产出。滇东南地区铝土矿形成于相对低能海湾环境中的潮间带～局限浅海，潮下带为成矿有利相带。海侵初期形成铁质岩、铁质泥岩和铁铝岩，最大海侵时期形成铝土岩。铝土矿的形成经历了古风化壳发育阶段、沉积—成岩阶段及表生阶段3个阶段。通过本区稳定元素（Sc、V、Nb和Ta）之间的比值及它们与Al₂O₃的比值，结合区域及矿区地质背景、铝土矿的钛率（Al₂O₃/TiO₂）、铝土矿（岩）石的稀土配分模式及特征参数分析，估算不同的物源形成的成矿物质铝的量，研究结果表明，滇东南地区铝土矿成矿物质具多来源特征，周围古陆（屏马—越北古陆、康滇古陆等）的前石炭系老岩系（铝硅酸盐、变质岩）、中-上二叠统玄武岩和上石炭统—中二叠统碳酸盐岩的风化剥蚀产物均为铝土矿的形成提供了一定的物质来源，其中玄武岩为主要的成矿物质来源。研究区由西南向北东方向越靠近局限浅海区，碳酸盐岩提供的物质来源相对逐渐增多。滇东南地区晚二叠世吴家坪早期沉积型铝土矿成矿作用的主要控矿因素为层位（层控）、沉积相（相控）、成矿物质来源（源控）和古构造环境。通过综合研究，确定了5个成矿有利远景区。更多还原

【Abstract】 The bauxite deposits are mainly distributed in the southeast of Yunnan province,regarded as one of the most predominant ore types in this area. Through analyses ofstratigraphy, petrography and geochemistry, a systematic research has been conductedon the sedimentary paleogeographic environment in the major mineralizationperiod—the Late Permian early Wujiaping period, and its associates to the bauxitemineralization, the characteristics of ore-bearing rock series, the geochemical featuresand the ore-controlling factors of the sedimentary bauxite deposits in southeastYunnan. The ore-forming materials, metallogenic regularity, prospecting criteria,genesis, metallogenic prospect areas are discussed and summarized.The sedimentary bauxite deposit in the study area is dominated by diasporicbauxite and its ore-bearing rock series are developed in the lower member of UpperPermian Wujiaping Stage. Diaspore is the main mineral, followed by kaolinite,anatase, goethite, etc., presenting a diversity of crystalline morphologies and modes ofoccurrence. Five main dissemination characteristics of diaspore are observed: a)unevenly disseminated in gangue minerals with euhedral or subhedral granulartextures ; b) in pisolitic, potato-shaped or oolitic forms; c) as aphanitic crystalline ormicrocrystalline aggregates or with irregular granular or microgranular texture; d) asveins, skeletal crystals; e) as aggregates of diaspore, alumina gel or gangue mineralsassuming zonal patterns or concentric circles.The bauxite deposits in the southeast of Yunnan province may form in thelow-energy gulf environment from the intertidal zone to shallow sea, and the subtidalzone is favourable to mineralization. The iron, iron-mud and iron-aluminum rocks areformed during the early stage of transgression, and the bauxite rock followed byduring the maximum transgression period. The formation of bauxite deposits, in turn,experienced the paleo-weathering crust development stage, the sedimentary-diagene-tic stage and the supergene secondary-leaching stage.Through analyzing the ratios of stable elements （Sc, V, Nb, Ta）, and the ratiosbetween stable elements and Al₂O₃, combining with the regional and mining areageological background, Al₂O₃/TiO₂, REE characteristic parameters and distributionpatterns of the bauxite and the content estimation of the metallogenic material-Alfrom different sources, the results show that there is a multi-source characteristic ofthe bauxite deposits in this area. The basalt is the main source of the bauxite, and the Pre-Carboniferous sediments of the ancient land （Pingma-Yuebei ancient land andKangdian ancient land）, and the carbonate rocks occurred in the Middle-UpperPermian are all likely to perform as the material sources for ore-forming. The amountof material source provided by carbonate rocks would increase gradually fromsouthwest to northeast nearer to the shallow sea.The major ore-controlling factors of sedimentary bauxite deposit in the southeastof Yunnan province occurred in the Late Permian Wujiaping period are horizon（strata-bound）, sedimentary facies （facies control）, material sources （source control）and paleotectonic environment. Five metallogenic prospect areas have been predictedbased on the systematic research.更多还原