The Busang mineral prospect in Kalimantan, Indonesia, was reported to host a large Au resource until 1997 when it was revealed that drill core samples had been deliberately and systematically contaminated (“salted”) with extraneous Au to falsify resource estimates. One month before the fraud was uncovered, Dr. G. Milligan, then professor emeritus of geology, visited the site to collect a suite of core samples for academic study that was deemed representative of the host rocks, alteration, and mineralization of the Busang Southeast Zone. These samples were re-examined here by optical microscopy, electron microprobe (EMPA), whole-rock geochemistry, and fluid inclusion microthermometry to characterize the subsurface geology and hydrothermal mineralization, and to assess reasons why the system is of uneconomic character. The host rocks were variably altered calc-alkaline porphyritic subvolcanic diorites, typical of the lithological units along the mineralized trend in the Kalimantan Gold Belt. Early hydrothermal mineralization with quartz-sulfide (pyrite, chalcopyrite, Cu-sulfosalts) stockwork veinlets associated with pervasive phyllic and propylitic alteration was overprinted by crudely banded quartz-carbonate-sulfide/sulfosalt (pyrite, sphalerite, chalcopyrite, galena, tennantite-tetrahedrite, bournonite-seligmannite) veins. The stockwork veins were associated with up to 140 ppb bulk rock Au, some of which was hosted by Cu-sulfosalts. Microthermometry on quartz-hosted aqueous fluid inclusion assemblages (FIA; n = 13) and single inclusions (non-FIA; n = 20) in quartz-carbonate-sulfide/sulfosalt veins yielded an overall range in homogenization temperatures (T_h) between 179 °C and 366 °C and bulk salinities between 1.1 wt.% to 8.6 wt.% NaCl equivalent, with much smaller data ranges for individual FIA (e.g., FIA 3; 239.1 °C to 240.5 °C and 0.5 wt.% to 1.4 wt.% NaCl equivalent). Primary FIA along growth zones in quartz were identified, providing constraints on fluid characteristics at the time of quartz growth. Carbonate-hosted FIA (n = 3) and single inclusions (non-FIA; n = 3) in the same veins yielded T_h between 254 °C and 343 °C and bulk salinities of 1.1 wt.% to 11.6 wt.% NaCl equivalent. Likewise, data ranges for individual FIA were much smaller. Many of the geological characteristics of the Busang Southeast Zone were compatible with a telescoped, intermediate-sulfidation epithermal system, having formed from diluted magmatic fluids that precipitated weak base metal mineralization. However, the system was unproductive with respect to Au and Ag, at least within the studied area. Of note, vein textures and fluid inclusion characteristics indicative of boiling or efficient fluid mixing—processes both considered critical for the formation of economic lode gold deposits—were absent in the samples.

中文翻译：

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印度尼西亚釜山东南区的超热矿化作用：Bre-X欺诈中心对金矿前景的新见解

据报道，印度尼西亚加里曼丹的釜山矿区拥有大量金矿资源，直到1997年才发现钻探岩心样品曾被故意和系统地污染（“盐化”）外来金以伪造资源估计。在发现欺诈之前一个月，当时的地质学名誉教授G. Milligan博士访问了该地点，收集了一套用于学术研究的核心样品，这些样品被认为是釜山东南部的宿主岩石，蚀变和矿化的代表。区。这些样品在这里通过光学显微镜，电子探针（EMPA），全岩地球化学和流体包裹体显微热学法进行了重新检查，以表征地下地质和热液成矿作用，并评估该系统具有非经济性的原因。宿主岩是钙-钙杂斑状亚火山岩的变质岩，是加里曼丹金矿带沿矿化趋势的典型岩性单元。石英-硫化碳-硫化物/亚硫酸盐（黄铁矿，闪锌矿，黄铜矿，方铅矿，黄铁矿-四面铁矿）与石英硫化物（黄铁矿，黄铜矿，铜-硫酸盐）储层细脉的早期热液矿化与普遍的叶绿素和次丙基改变有关。钠钙锰矿-钙锰矿）脉。储层脉脉与高达140 ppb的块状金Au有关，其中一些是由Cu-硫酸盐包埋的。石英载水包裹体组合的显微热分析法（FIA; 石英-硫化物-硫化物/亚硫酸盐（黄铁矿，闪锌矿，黄铜矿，方铅矿，黄铁矿-四面铁矿）与石英硫化物（黄铁矿，黄铜矿，铜-硫酸盐）储层细脉的早期热液矿化与普遍的叶绿素和丙二酸蚀变有关。钠钙锰矿-钙锰矿）脉。储层脉脉与高达140 ppb的块状金Au有关，其中一些是由Cu-硫酸盐包埋的。石英载水包裹体组合的显微热分析法（FIA; 石英-硫化物-硫化物/亚硫酸盐（黄铁矿，闪锌矿，黄铜矿，方铅矿，黄铁矿-四面铁矿）与石英硫化物（黄铁矿，黄铜矿，铜-硫酸盐）储层细脉的早期热液矿化与普遍的叶绿素和丙二酸蚀变有关。钠钙锰矿-钙锰矿）脉。储层脉脉与高达140 ppb的块状金Au有关，其中一些是由Cu-硫酸盐包埋的。石英载水包裹体组合的显微热分析法（FIA; 储层脉脉与高达140 ppb的块状金Au有关，其中一些是由Cu-硫酸盐包埋的。石英载水包裹体组合的显微热分析法（FIA; 储层脉脉与高达140 ppb的块状金Au有关，其中一些是由Cu-硫酸盐包埋的。石英载水包裹体组合的显微热分析法（FIA;n = 13）和石英-碳酸盐-硫化物/硫酸盐矿脉中的单一夹杂物（non-FIA; n = 20）在179°C至366°C的均质温度（T _h）范围内以及整体盐度在1.1 wt NaCl当量为0.5％至8.6 wt％NaCl当量，单个FIA的数据范围要小得多（例如FIA 3； 239.1°C至240.5°C和0.5 wt％至1.4 wt。％NaCl当量）。确定了沿石英生长区的主要FIA，从而限制了石英生长时的流体特性。碳酸盐岩样的FIA（n = 3）和同一静脉中的单个夹杂物（非FIA；n = 3）产生T _h在254°C至343°C之间的温度范围内，总盐度为1.1 wt。％至11.6 wt。％NaCl当量。同样，单个FIA的数据范围要小得多。釜山东南区的许多地质特征都与一个伸缩的，中间硫化的超热系统兼容，该系统由稀释的岩浆流体形成，使弱碱金属矿化沉淀。但是，至少在研究区域内，该系统对金和银没有作用。值得注意的是，样品中缺乏指示沸腾或有效流体混合的静脉纹理和流体包裹体特征（这些过程均被认为对形成经济金矿床至关重要）。