Interpretation of various exploration data, in particular geochemical prospecting, offers a powerful and rapid assessment of grass-root projects in a green-field terrain. Here, we present an example of the Collins epithermal prospect in Aceh Province, Indonesia. In this area, the Au+ base-metal-bearing sheeted quartz veins (individually mostly 2–4 cm wide), which are controlled by a 250 m wide by 800 m long NNE-trending structural corridor within Paleogene sandstone and volcanic rocks, are the product of two main stages of deposition. Stage I formed veins with a sliver of cryptocrystalline quartz wall zone followed by an inner zone of comb quartz with interstitial rhombic adularia that terminates in open space. Stage I or main-stage sulfide mineralization consisting of early galena + sphalerite and later chalcopyrite occurs with the quartz + adularia. Small amounts of galena also occur in the wall zone. Stage II mineralization brecciated Stage I veins and overprinted them with silicification characterized by vuggy texture. Mineralization associated with this episode consists of earlier chalcopyrite + sphalerite + tennantite–tetrahedrite and later, vug-filling Au–Ag alloy (Ag_0.37–0.41Au_0.62–0.59). The above mineralized veins are successively flanked by silicic selvages, an illite + chlorite + pyrite ± kaolinite zone and a chlorite + epidote + carbonate + pyrite zone. Local supergene alteration induced replacement of galena by plumbogummite and anglesite and chalcopyrite by covellite. Data from fluid inclusion microthermometry in quartz indicated that the inner zone of Stage I veins formed from fluids with a 2.3 wt% salinity (0.5–3.3 wt% NaCl equivalent), at 174°C (155–211°C). Combining these physico-chemical parameters with the mineral assemblage, the mineralization occurred under a reduced environment. Rock and soil assays indicate that elevated Au concentrations (up to 16.5 ppm over 1 m) occur along northeast-trending zones and show a strong correlation with Pb, while Cu (up to 2.58% over 1 m), Zn, As, Sb, and Mo anomalies lie mostly at the periphery. The high-grade mineralized veins correlate with moderate to high resistivity and chargeability zones, and the pseudosections of such geophysical signals are interpreted as reflecting coalesced or enlarged veins at depth, or inclined veins in other localities. The intermediate sulfidation affinity for Collins points to potential mineralization at depth as well as preservation of Au-rich and sulfide-poor zones in the less eroded areas.

中文翻译：

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印度尼西亚亚齐柯林斯超热液金基金属远景的初步勘探结果

各种勘探数据的解释，特别是地球化学勘探，为绿地中的基层项目提供了强大而快速的评估。在这里，我们展示了印度尼西亚亚齐省柯林斯超热液前景的一个例子。该区以古近系砂岩和火山岩内250 m宽、800 m长的NNE向构造廊道控制的含Au+贱金属片状石英脉（个别宽2～4 cm）为两个主要沉积阶段的产物。第一阶段形成了带有隐晶质石英壁带的脉络，然后是梳状石英的内部区域，其间质菱形adularia终止于开放空间。由早期方铅矿 + 闪锌矿和晚期黄铜矿组成的第一阶段或主要阶段的硫化物矿化与石英 + adularia 一起出现。少量方铅矿也出现在壁区。II 期矿化使 I 期矿脉形成角砾，并用具有孔洞纹理特征的硅化叠印它们。与这一事件相关的矿化包括早期的黄铜矿 + 闪锌矿 + 钛锌矿-四面体和后来的填孔 Au-Ag 合金（Ag_0.37–0.41金_0.62–0.59）。上述矿化脉侧依次为硅质边、伊利石+绿泥石+黄铁矿±高岭石带和绿泥石+绿帘石+碳酸盐+黄铁矿带。局部表生蚀变导致铅铅矿替代方铅矿、方铅矿和铜蓝矿替代黄铜矿。石英流体包裹体显微测温数据表明，I 期脉的内部区域由 2.3 wt% 盐度（0.5-3.3 wt% NaCl 当量）的流体在 174°C（155-211°C）形成。将这些物理化学参数与矿物组合相结合，矿化发生在还原环境下。岩石和土壤分析表明，沿东北方向的趋势区域中，Au 浓度升高（在 1 m 范围内高达 16.5 ppm）并显示出与 Pb 的强相关性，而 Cu（在 1 m 范围内高达 2.58%）、Zn、As、Sb、Mo异常主要位于外围。高品位矿化脉与中到高电阻率和带电区相关，这种地球物理信号的假断面被解释为反映深度处合并或扩大的脉，或其他地方的倾斜脉。柯林斯的中间硫化亲和力表明在深度潜在的矿化以及在侵蚀较少的地区保存了富含金和缺乏硫化物的区域。