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黄金的重要来源，自20世纪80年代中期发现储量达5000万盎司的巨型亚纳科查矿床(秘鲁)以来，一直受到越来越多的关注。金子。然而，与低硫化浅成热液铜矿和斑岩型铜矿床相比，高硫化浅成热液金矿床认识较少。随着矿业公司越来越依赖遗传模型来指导他们的勘探战略，我们更有必要提高对成矿过程的理解。虽然一致认为这些矿床形成于火山建筑物内，凝聚的岩浆蒸气负责地面准备，但对于成矿流体的性质、金的溶解方式和矿化的时间，人们的共识要少得多。在许多情况下，有证据表明金的引入较晚，对于这些矿床，研究人员提出了不同的观点，认为成矿流体来自岩浆成因、吸收岩浆蒸气的陨石液体或不通过两相区而收缩为液体的岩浆蒸气；亚硫化物和氯化物络合物都被用作黄金运移的媒介。然而，在某些情况下，有证据表明，地面准备和金矿化是准同时代的，这意味着金是通过蒸汽运输的，可能是以水合氯化物或硫化物的形式。这项建议是为了对两个高硫化矿床(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，前者的金矿矿化似乎发生在早期(与黄铁矿化有关)，后者显示出高硫化蚀变的证据，包括黄铁矿化。这项研究的目的是通过对矿化和蚀变进行岩石学和地球化学表征，重建成矿的物理化学条件，确定Kawah Ijen流体的组成，并通过实验研究其载金能力，建立成因模型。如果成功，该项目将有助于完善现有的高硫化矿化模型和勘探战略。

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.