【作者】 王冉；

【导师】 桑树勋；

【作者基本信息】 中国矿业大学 ， 地球化学， 2011， 博士

【摘要】 运用煤地球化学、微量元素地球化学、煤岩学、煤田地质学、矿物学和岩石学的相关理论知识,系统研究了黔西上二叠统主要含煤地层中Au等伴生元素的地球化学行为,查明了煤中Au的主要分布特征,揭示了Au地球化学异常的地质控制因素;通过数理统计分析和逐级化学提取实验研究分析了煤中Au的赋存状态及主要载金矿物,揭示了研究区煤中Au赋存状态的复杂性,Au主要以无机态存在,煤中黄铁矿可能是Au的主要载体矿物;进而通过探讨煤中Au的物质来源及迁移富集过程,建立了煤中Au迁移富集的地质—地球化学机理。论文研究成果对丰富发展煤中Au的地球化学行为理论、科学预测评价煤中稀散金属矿产潜力具有理论和现实意义。论文研究表明:①黔西上二叠统煤中Au含量普遍高于其地壳丰度、美国煤、世界煤及中国各聚煤期煤中Au的平均含量,Au高异常的最大值存在于含煤页岩中,Au地球化学高异常区主要集中在北西向紫云—垭都深断裂与北东向师宗—贵阳深断裂及东西向开远—平塘断裂所构成的“三角形”区域内;②由于晚二叠世峨眉地幔热柱活动强烈,断裂带大量发育,加之同沉积断裂的共同影响,导致上扬子地台的稳定性较差,这不仅为同期和后期的岩浆活动及低温热液活动提供了条件,成为煤遭受变质的重要因素,也是控制煤中Au地球化学高异常的主控地质因素;③煤中Au的赋存状态复杂多样,数理统计分析和逐级化学提取实验结果指示,煤中Au的无机亲和能力大于有机亲和能力,在煤中Au主要以无机态存在,黄铁矿是Au的主要载体矿物,而Au在煤中主要以纳米级分散形式存在;④煤中Au具有多源性,但Au与峨眉地幔热柱及低温热液的关系表明,Au的内生来源(岩浆活动和低温热液)是黔西煤中Au的主要物质来源,断裂带不仅为低温热液提供了古地温,也成为含Au低温热液进入煤层的通道;⑤构造运动、低温热液活动、岩相古地理条件对Au的活化、迁移及煤中富集存在显著影响,黔西含煤地层中Au的富集过程,实际上是峨眉地幔热柱活动形成的低温热液流体从地幔向地壳演化过程中Au等元素活化→迁移→富集的过程。从煤中Au的分布特征、赋存特征和富集规律看,煤中Au的富集类型为深大断裂—低温热液作用型。该论文有图55幅,表33个,参考文献286篇。更多还原

【Abstract】 This paper uses the theories of coal geochemistry, trace element geochemistry, coal petrology, coal geology, mineralogy and petrology to systematically investigate the geochemical behavior of Au and other associated elements of Upper Permian coal-bearing formation in Western Guizhou Province, find out the main distribution characteristics of Au in coals and reveal the geological controlling factors of Au geochemical anomaly. On the basis of the mathematical statistical analysis and the data from the sequential chemical extraction , the occurrence of gold in coals and the main gold-bearing mineral are analyzed .It reveals the complexity of the occurrence of gold in coals that exists mainly in inorganic forms, and the pyrite in coals may be the main carrier mineral of gold. Further more, this paper discusses the material sources and the processes of transportation deposition and enrichment of gold in coals, establishes the geological and geochemical mechanism for the migration enrichment of gold in coals. The results of the study have theoretical and realistic significance to improve the theory of geochemical behavior and scientifically predict the mineral resource potentials of scattered metals.The research comes to the results:①The concentration of gold in Upper Permian coal in southwest Guizhou Province is generally higher than the crust abundance and the average concentration of gold in America or the other coal-accumulating periods in China. The anomalous concentration of gold in shale comes to be highest. Areas where the anomalous concentration of gold is really high are mainly distributed in the“triangle”area including NW-trending Ziyun—Yadu deep fault, NE-trending Shizong—Guiyang deep fault and EW-trending Kaiyuan--Pingtang fault.②There are many reasons for instability of the Upper Yangtze platform: the intense activity of Emei mantle plume in Late Permian, many fault zones and sedimentary fracture. It is not only the main factors of coal metamorphism, but also providing the conditions of deep magmatic activities and low-temperature hydrothermal. Further more, it is considered to be the main geological factors of anomalous concentration of gold in coals of Western Guizhou, Province.③Though the occurrence state of gold in coals in research area is complicated, the inorganic affinity is stronger than the organic affinity according to the mathematical statistics analysis and the results from the sequential chemical extraction.The gold in coals exists mainly in inorganic forms, that is , nano-gold is the form of existence in coal. The pyrite in coals may be the main carrier mineral of gold.④The gold in coals comes from multiple sources, but the endophytic source of gold (magmatic activity and epithermal fluid) is the main material source of the gold in coals in Western Guizhou Province based on the relation among gold, Emei mantle plume and epithermal fluid. The fault belt not only provides paleo-geotherm for epithermal fluid, but also becomes the channel for the gold contained in the epithermal fluid.⑤Tectonic movements, epithermal fluid and lithofacies paleogeography have significant effect on the activation, transportation and precipitation of the gold in coals. The enrichment process of the gold in coals in Western Guizhou Province is actually the activation→transportation→enrichment process of the gold along with the epithermal fluid that is resulted from Emei mantle plume activity coming from mantle to crust. In accordance with the distribution characteristics, enrichment regularities and occurrence modes of gold in coals, the enrichment type of gold in coals is from deep faulted zone to low temperature hydrothermal activation.There are 55 figures, 33 tables and 286 references in the dissertation.更多还原