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

完整项目标题：岩浆、流体、断层和金属——重新评估与英格兰西南部Cornubian岩基相关的岩浆热液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岩基为中心，是岩浆-热液矿化与过铝质花岗岩和矿物分带相关的全球范例，其优势矿物组合往往随着距离花岗岩的远近而逐渐变化（近端为W-Sn + /minus As，远端为Cu， Zn和Pb）。“发散中心”周围金属的非均质分布和矿化风格，包括大量铜与过铝花岗岩的异常赋存，表明岩浆作用、岩浆挥发相分离、断裂作用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的广泛分布和金属远景（Simons etal ., 2017）。该项目的重点是描述矿化过程中涉及的流体类型，以及它们的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。项目目标和方法该项目的重点是系统分析来自英格兰西南部矿田不同花岗岩类型和矿化风格的熔体和流体包裹体。这些将用于确定：(1)初生岩浆-热液流体的成分可变性及其通过熔融成分演变的控制；(2)控制这些溶液中矿石金属沉淀的参数（如冷却、相分离、围岩反应）。仔细的样品矿物学和岩石学，包括SEM， QEMSCAN和阴极发光技术，将支持使用显微测温和激光烧蚀ICP-MS进行流体包裹体微观分析。矿物的同位素分析将用于评价流体来源和演化的备选模型。这些数据将与同岩浆断层系统的分布和历史金属生产相结合，重新评价对矿化的控制、矿物分带和“发散中心”的起源。该项目将利用自然历史博物馆、伦敦帝国理工学院和坎伯恩矿业学院的藏品，但需要实地考察，从侵入体和矿脉组之间的交叉关系可以详细记录的地区收集样本。CASE合作伙伴目前和最近的勘探为从金刚石钻岩心样品中取样提供了无与伦比的机会。

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.