Origin of Ore‐forming Fluids Responsible for Gold Mineralization of the Pongkor Au‐Ag Deposit, West Java, Indonesia: Evidence from Mineralogic, Fluid Inclusion Microthermometry and Stable Isotope Study of the Ciurug–Cikoret Veins
Origin of Ore‐forming Fluids Responsible for Gold Mineralization of the Pongkor Au‐Ag Deposit, West Java, Indonesia: Evidence from Mineralogic, Fluid Inclusion Microthermometry and Stable Isotope Study of the Ciurug–Cikoret Veins
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DOI：
10.1111/j.1751-3928.2007.00013.x
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发表时间：
2007-06
期刊：
影响因子：
1.4
通讯作者：
A. Imai;Koichiro Watanabe
中科院分区：
文献类型：
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作者：
A. Imai;Koichiro Watanabe
Pongkor金银矿位于巴亚穹丘的东北侧，该穹丘是Sunda-Banda弧火山活动的产物。Ciurug-Cikoret地区的热液蚀变矿物是酸性至近中性pH热沃茨形成的典型矿物。在表面上，伊利石/蒙皂石混层矿物（I/Sm）、蒙皂石和高岭石，以及矿化带顶部的点状伊利石、I/Sm和钾长石蚀变。硅化、钾长石和I/Sm带通常形成于围岩中，并逐渐向外渐变为青岩带。贵金属矿带的成矿作用受流体温度的制约，温度在180 - 220°C之间，盐度低（<0.2wt%NaCl当量），处于沸腾状态。对于静水压柱，古地下水位以下矿脉形成的最小深度约为90-130 m。石英和方解石的氢和氧同位素数据显示流体成分相对均匀（δD为−53至−68‰，δ 18 O H2O为−5.7至+0.3‰）。在矿化阶段和高程方面，数据中没有特定的趋势，这表明成矿流体在矿脉形成期间没有显著的空间变化。稳定同位素数据表明热液流体与大气降水发生了混合作用，热液流体与寄主岩石发生了相互作用。
The Pongkor gold–silver mine is situated at the northeastern flank of the Bayah dome, which is a product of volcanism in the Sunda–Banda Arc. The hydrothermal alteration minerals in the Ciurug–Cikoret area are typical of those formed from acid to near‐neutral pH thermal waters. On the surface, illite/smectite mixed layer mineral (I/Sm), smectite and kaolinite, and spotting illite, I/Sm and K‐feldspar alteration occur at the top of the mineralized zone. Silicification, K‐feldspar and I/Sm zones are commonly formed in the wall rock, and gradually grade outwards into a propylitic zone. The mineralization of precious metal ore zone is constrained by fluid temperatures between 180 and 220°C, and with low salinity (<0.2 wt% NaCl equivalent) and boiling condition. The minimum depth of vein formation below the paleo‐water table is approximately 90–130 m for the hydrostatic column. Hydrogen and oxygen isotope data for quartz and calcite show relatively homogeneous fluid composition (−53 to −68‰δD and −5.7 to +0.3‰δ18O H2O). There is no specific trend in the data with respect to the mineralization stages and elevation, which suggests that the ore‐forming fluids did not significantly change spatially during the vein formation. The stable isotope data indicate mixing between the hydrothermal fluids and meteoric water and interaction between the hydrothermal fluids and the host rock.