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

全项目标题：岩浆、流体、断层和金属-重新评估与英格兰西南部科努比安岩基有关的岩浆热液W-锡-铜-砷-锌-铅矿化和分带的控制。W-锡-铜-砷-锌-铅矿田以早二叠世科努比安岩基为中心，是与过铝花岗岩和矿物分带有关的岩浆热液矿化的全球典范，其中主要矿物组合往往随着距离花岗岩的距离而逐渐变化(W-Sn加/减近端和远端的铜、锌和铅)。“发散中心”周围金属和矿化类型的不均匀分布，包括过铝花岗岩中大量铜的异常赋存，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。源岩熔融和分异的变化控制了花岗岩类型和金属远景的广泛分布(Simons等人，2017年)。该项目的重点是描述成矿所涉及的流体类型，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。项目目标和方法该项目重点是对英格兰西南部矿田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。它们将被用来确定：(1)原生出溶岩浆-热液流体的成分变异性及其通过熔体成分演化的控制，以及(2)控制从这些溶液中析出矿金属的参数(如冷却、相分离、围岩反应)。仔细的样品矿物学和岩石学，包括扫描电子显微镜、QEMSCAN和阴极发光技术，将支持使用显微测温法和激光消融电感耦合等离子体质谱进行的流体包裹体微量分析。矿物的同位素分析将被用来评估流体来源和演化的替代模型。这些数据将与同岩浆断裂系统的分布和历史金属产量相结合，以重新评估对矿化、矿物分带和“发散中心”起源的控制。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中的材料，但需要实地工作，从可以详细记录侵入物与静脉之间的横向关系的地区收集样本。Case合作伙伴目前和最近的勘探提供了一个从钻石钻芯样品中取样的无与伦比的机会。

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.