Magmas, fluids, faults & metals - re-assessing the controls on magmatic-hydrothermal mineralisation & zonation associated with the Cornubian Batholith

完整项目名称：岩浆、流体、断层和金属--重新评估与英格兰西南部Cornubian火山岩有关的岩浆热液W-Sn-Cu-As-Zn-Pb矿化和分带的控制因素。W-Sn-Cu-As-Zn-Pb矿田以早二叠世Cornubian火山岩为中心，是与过铝质花岗岩和矿物分带有关的岩浆热液矿化的全球范例，随着距花岗岩的距离增加，优势矿物组合往往发生渐进变化（近端W-Sn加/减As，远端Cu、Zn和Pb）。“放射中心”周围金属和矿化类型的不均匀分布，包括大量铜与过铝质花岗岩的异常出现，表明岩浆作用、岩浆挥发相分离、断层和流体混合之间存在复杂的关系。源熔融和分异的变化控制着花岗岩类型和金属远景的广泛分布（Simons等人，2017年）。该项目的重点是研究矿化过程中所涉及的流体类型，以及它们受构造控制的迁移和混合如何控制矿物组合和金属分布的变化。项目目的和方法该项目的重点是对英格兰西南部矿区不同花岗岩类型和矿化类型中的熔体和流体包裹体进行系统分析。这些将被用来确定：（1）主要的出溶岩浆-热液流体的组成变化和他们的控制，通过不断演变的熔体组成，和（2）控制从这些解决方案的金属沉淀的参数（如冷却，相分离，围岩反应）。仔细的样品矿物学和岩相学，包括扫描电镜，QEMSCAN和阴极发光技术，将支持流体包裹体显微分析使用显微测温和激光烧蚀ICP-MS。同位素分析的矿物将被用来评估替代模型的来源和流体的演变。这些数据将与同岩浆断层系统和历史金属生产的分布相结合，以提供对矿化，矿物分带和“放射中心”起源的控制的重新评估。该项目将利用自然历史博物馆，伦敦帝国理工学院伦敦和Camborne矿业学院的收藏品中的材料，但需要进行实地调查，以收集侵入体和静脉集之间的交叉关系可以详细记录的区域的样本。CASE合作伙伴目前和最近的勘探提供了一个无与伦比的机会，从金刚石钻芯样品中取样。

Full project title: Magmas, fluids, faults and metals - re-assessing the controls on magmatic-hydrothermal W-Sn-Cu-As-Zn-Pb mineralisation and zonation associated with the Cornubian Batholith, SW England.The W-Sn-Cu-As-Zn-Pb ore field, centred upon the Early Permian Cornubian Batholith, is a global exemplar of magmatic-hydrothermal mineralisation associated with peraluminous granites and mineral zonation, where there is often a progressive change in dominant mineral assemblage with distance from the granite (W-Sn plus/minus As proximal and Cu, Zn and Pb distal). The heterogeneous distribution of metals and mineralisation styles around "emanative centres", including the anomalous occurrence of substantial Cu with peraluminous granite, indicates a complex relationship between magmatism, separation of magmatic volatile phases, faulting and fluid mixing. Changes in source melting and differentiation control the broad distribution of granite types and metal prospectivity (Simons et al., 2017). The focus of this project is to characterise the fluid types involved in mineralisation and how their structurally-controlled migration and mixing has controlled variations in the distribution of mineral assemblages and metals.Project Aims and MethodsThe project is focussed upon the systematic analysis of melt and fluid inclusions in different granite types and mineralisation styles from across the SW England orefield. These will be used to determine: (1) the compositional variability of primary exsolved magmatic-hydrothermal fluids and their control by evolving melt compositions, and (2) the parameters controlling precipitation of ore metals from these solutions (e.g. cooling, phase separation, wall-rock reaction). Careful sample mineralogy and petrography, including SEM, QEMSCAN and cathodoluminescence techniques, will underpin the fluid inclusion microanalysis using microthermometry and laser ablation ICP-MS. Isotopic analysis of minerals will be used to evaluate alternative models for the source and evolution of fluids. These data will be combined with the distribution of syn-magmatic fault systems and historical metal production, to provide a re-evaluation of the controls on mineralisation, mineral zonation and the origin of "emanative centres". The project will utilise material from collections at the Natural History Museum, Imperial College London and Camborne School of Mines but will require fieldwork to collect samples from areas where cross-cutting relationships between intrusions and vein sets can be documented in detail. Current and recent exploration by the CASE partners has provides an unparalleled opportunity to sample from diamond drill core samples.