Alluvial gold is abundant in the Quaternary deposits of the Kabul and Indus rivers in District Nowshera, Khyber Pakhtunkhwa, Pakistan. Understanding the provenance of alluvial gold using morphology and elemental composition could be helpful in developing an exploration strategy of regional benefit. Detailed morphological studies of gold grains revealed high flatness index values which are indicative of a distal source. Compositional studies of 58 gold grains using SEM and EMPA showed broadly similar Ag ranges (1–15 wt%) for each sample and occasional Cu values in individual gold particles to 0.4 wt%. Whilst the Ag profile is not diagnostic, the Cu values are compatible with derivation from either porphyry systems or ultrabasic rocks. The complex geology of the drainage catchments could host gold mineralization of other styles, but larger sample suites would be required to refine the current interpretation to establish whether particles which are simple Au-Ag alloys could be derived from orogenic or epithermal sources. This scoping study has demonstrated that the compositional and morphological studies of gold grains are useful in providing information regarding the nature and location of the source of placer gold in areas where there is limited information on the nature and location of in situ mineralization.

中文翻译：

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使用冲积金形态学和合金成分的勘探方法：巴基斯坦开伯尔-普赫图赫瓦省 Nowshera 区第四系矿床的案例研究

巴基斯坦开伯尔-普赫图赫瓦省Nowshera区的喀布尔河和印度河的第四纪矿床中蕴藏着丰富的冲积金。使用形态和元素组成了解冲积金的来源可能有助于制定区域效益的勘探策略。金颗粒的详细形态研究揭示了高平坦度指数值，表明存在远端源。使用 SEM 和 EMPA 对 58 个金颗粒的成分研究表明，每个样品的 Ag 范围大致相似（1-15 wt%），个别金颗粒中的 Cu 值偶尔达到 0.4 wt%。虽然 Ag 剖面不是诊断性的，但 Cu 值与来自斑岩系统或超基性岩的推导一致。排水集水区的复杂地质可能承载其他类型的金矿化，但是需要更大的样本套件来完善当前的解释，以确定简单的 Au-Ag 合金颗粒是否可以来自造山或超热源。该范围界定研究表明，在原位矿化的性质和位置信息有限的地区，金颗粒的成分和形态研究有助于提供有关砂金来源的性质和位置的信息。