The genesis of high sulphidation gold: a comparative study of the Bowone-Binebase deposits and Kawah Ijen volcano, Indonesia

高硫化浅成热液矿床是一种重要的金来源，自20世纪80年代中期发现资源量超过5 000万盎司的Yanacocha大型存款（秘鲁）以来，一直受到越来越多的关注。黄金然而，相对于其近缘低硫化型浅成低温热液矿床和斑岩型铜矿床，高硫化型浅成低温热液金矿床的认识却很少。由于采矿公司越来越依赖成因模型来指导其勘探战略，因此更需要提高我们对成矿过程的理解。虽然人们一致认为这些矿床是在火山机构内形成的，并且凝结的岩浆蒸汽是地面准备的原因，但对矿石流体的性质、金溶解的方式和矿化的时间却没有太多的共识。在许多情况下，有证据表明金是在晚期引入的，对于这些矿床，研究人员提出了各种各样的观点，认为矿石流体是岩浆起源的，是吸收岩浆蒸汽的流星液体，或者是不通过两相区而收缩成液体的岩浆蒸汽;二硫化物和氯化物复合物都被认为是金的运输媒介。然而，在某些情况下，有证据表明，地面准备和金矿化是同时期的，这意味着黄金是通过蒸汽运输的，可能是水合氯化物或硫化物。本提案旨在对一对高硫化矿床（印度尼西亚Bowone-Binebase）和一座活火山（印度尼西亚Kawah Ijen）进行比较研究，前者的金矿化似乎很早（与黄铁矿化有关），后者显示出高硫化蚀变（包括黄铁矿化）的证据。研究的目的是通过岩石学和地球化学特征的矿化和蚀变，重建成矿的物理化学条件，确定卡瓦Ijen流体的组成，并通过实验研究其黄金运输能力，开发一个成因模型。如果成功，该项目将有助于完善现有的高硫化矿化模型及其勘探策略。

High sulphidation epithermal deposits are an important source of gold that has been receiving increased attention since discovery of the giant Yanacocha deposit (Peru) in the mid-1980s with a resource of >50 million oz. gold. However, in comparison to their relatives, low sulphidation epithermal and porphyry copper deposits, high sulphidation epithermal gold deposits are poorly understood. As mining companies are become increasingly dependent on genetic models to guide their exploration strategies, there is greater need to improve our understanding of ore-forming processes. Although there is agreement that these deposits form within volcanic edifices and that condensed magmatic vapours are responsible for ground preparation, there is much less agreement on the nature of the ore fluids, the manner in which the gold is dissolved, and the timing of mineralisation. In many cases, there is evidence for late introduction of gold and for these deposits, researchers have variously proposed that the ore fluid is of magmatic origin, meteoric liquid that absorbed magmatic vapour, or magmatic vapour that contracted to liquid without passing through the two-phase region; both bisulphide and chloride complexes have been invoked as agents of gold transport. However, in some cases, there is evidence that ground preparation and gold mineralisation were pene-contemporaneous, implying that gold was transported by vapour, possibly as a hydrated chloride or sulphide species. This proposal is for a comparative study of a pair of high sulphidation deposits (Bowone-Binebase, Indonesia) in which gold mineralisation appears to have been early (associated with pyritisation), and an active volcano (Kawah Ijen, Indonesia) which shows evidence of high sulphidation alteration, including pyritisation. The objective of the research is to develop a genetic model by characterising petrographically and geochemically the mineralisation and alteration, reconstructing the physicochemical conditions of ore formation, determining the composition of Kawah Ijen fluids, and experimentally investigating their gold transporting capacity. If successful, the project will help refine existing models for high sulphidation mineralisation and strategies for its exploration.