Development of geochemical and mineralogical methods for targeting lower environmental impact secondary copper deposits in the Troodos Massif, Cyprus

塞浦路斯的Troodos Massif自青铜时代就开始开采，蕴藏着大约90个铜矿(Robb，2005)。采矿主要集中在含有黄铁矿和黄铜矿的原生火山成因岩块硫化物型矿床，闪锌矿较少。随着最近铜价的上涨，勘探目标的范围已扩大到包括较低品位的次生(表生富集型)矿床。这主要是原生黄铁矿被大气渗流流体氧化，导致流体pH降低，随后黄铜矿溶解的结果。大部分铜进入流体相，并在更深的层面上以氧化物的形式沉淀，在地下水位以上或以下以硫化物的形式沉淀。次生铜矿的开采提供了环境效益，因为次生铜矿更易于酸浸，而不是硫化矿石所需的矿石选矿和冶炼。对欧洲铜的勘探还提供了与供应安全有关的财务、其他环境(较低金属里程)和战略利益。该项目的目的是开发新的次生铜矿勘探工具，检验以下假设：1)根据矿物学和地球化学标准，地表铜矿可分为高铜硫化物原岩形成的铜矿和低铜硫化物原岩形成的铜矿；2)高铜原岩形成的铜矿可能表明深部存在次生铜矿。学生将按照莱伯恩等人的方法，在特罗多斯山进行详细的实地研究，并收集铁山样本和地下水。(2006年)。将研究五个戈萨矿：菲尼克斯和三个Hills矿床，已知的次生铜矿化；两个“贫瘠”的戈桑矿，将在实地考察和与塞浦路斯地质调查局的讨论中确定；以及尚未开发的West Apliki矿藏(Naden等人，2006年)。样品将使用光学和扫描电子显微镜(Camborne School of Mines-CSM)进行检查，然后使用QEMSCAN自动矿物学评估系统(在CSM)和位置灵敏探测器-X射线衍射(PSD-X射线衍射仪，在NHM)进行分析。将在CSM使用X射线荧光和在NHM使用电感耦合等离子体光发射(ICP-OES)和质谱仪(ICP-MS)获取补充的全样品主要和微量元素数据。空间分辨的痕量元素数据将在NHM或BGS使用激光烧蚀电感耦合等离子体质谱获得。根据残存矿物和交代结构的存在与否，以及风化相(包括粘土)的矿物学和元素组成，将制定已知的由高铜原岩和低铜原岩形成的角岩的分类方案。通过使用大量和矿物地球化学数据(包括稀土元素，使用Boyle，2003年的方法)进行质量平衡计算，将评估来自高铜原岩的戈桑的风化程度和性质。学生将在塞浦路斯的两个为期四周的田野季节期间接受所有三位监督员的野外地质测绘和取样指导，第一个在菲尼克斯、三山和“荒野”遗址进行详细研究，第二个在西阿普利基探矿的半勘探环境中测试开发的模型。已经与EMED(Nikos Adamdes)和塞浦路斯政府地质调查局(Dr Eleni Morriseau)进行了接触，以确保为学生提供出色的后勤支持。将在NHM提供PSD-XRD和地球化学法(ICPOES、ICPMS和LA-ICPMS)分析方面的全面培训，并在CSM提供扫描电子显微镜、X射线荧光和QEMSCAN方面的全面培训。有关参考，请参阅支持案例

The Troodos Massif, Cyprus has been mined since the Bronze age and contains around 90 copper deposits (Robb, 2005). Mining has mainly concentrated on the primary volcanogenic massif sulphide-type deposits containing pyrite and chalcopyrite, with lesser sphalerite. With the recent increase in the price of Cu, the range of exploration targets has been broadened to include lower grade secondary (supergene enrichment) deposits. These form mainly as a result of oxidation of primary pyrite by percolating meteoric fluids which causes a reduction in pH of the fluids and subsequent dissolution of chalcopyrite. Much of the Cu enters the fluid phase and is precipitated at deeper levels as either oxides, above the water table, or as sulphides below it. The mining of secondary deposits offers environmental benefits as secondary copper minerals are more amenable to acid leaching rather than the ore beneficiation and smelting necessary for sulphide ores. The exploration for European Cu also offers financial, other environmental (lower metals miles) and strategic benefits relating to security of supply. The aim of the project is to develop new exploration tools for secondary Cu deposits by testing the hypotheses that: 1) surface gossans can be classified, based on mineralogical and geochemical criteria, into those developed from high- and low-Cu sulphide protoliths; 2) gossans formed from high-Cu protoliths may indicate the existence of secondary copper deposits at depth. The student will carrying out detailed field studies in the Troodos Massif and the collection of gossan samples and ground waters, following methods in Leybourne et al. (2006). Five gossans will be studied: the Phoenix and Three Hills deposits, with known secondary Cu mineralisation; two 'barren' gossan sites, to be identified during fieldwork and from discussions with the Cyprus Geological Survey; and the West Apliki prospect, which is as yet undeveloped (Naden et al., 2006). Samples will be examined using optical and scanning electron microscopy (at the Camborne School of Mines - CSM), and then analysed using QEMSCAN automated mineralogical assessment system (at CSM) and by Position Sensitive Detector - X-ray diffraction (PSD-XRD, at the NHM). Complementary whole-sample major and trace element data will be acquired at CSM using X-ray fluorescence and at the NHM using Inductively Coupled Plasma Optical Emission (ICP-OES) and Mass Spectrometry (ICP-MS). Spatially resolved trace element data will be obtained using Laser Ablation ICP-MS at the NHM, or BGS. A classification scheme for gossans known to be formed from high- and low-Cu protoliths will be devised on the basis of the presence/absence of relict minerals and replacement textures and the mineralogy and elemental composition of weathering phases, including clays. The extent and nature of the weathering in gossans from high-Cu protoliths will be assessed by carrying out mass balance calculations using bulk and mineral geochemical data (including rare earth elements, using the method of Boyle, 2003). The student will receive instruction in field geological mapping and sampling from all three supervisors during two field seasons in Cyprus, of four weeks each, the first to undertake detailed studies at the Phoenix, Three Hills and 'barren' sites and the second to test developed models in a semi-exploration context at the West Apliki prospect. Contacts have been made with EMed (Nikos Adamides) and the Geological Survey Department of the Cyprus government (Dr Eleni Morriseau) ensuring excellent student logistical support. Full training will be given at the NHM in PSD-XRD and geochemical (ICP-OES, ICP-MS and LA-ICP-MS) analysis and at CSM in scanning electron microscopy, X-ray fluorescence and QEMSCAN. For references see Case for Support