Karakteristik Mineralogi dan Geokimia serta Distribusi Spasial Cu-Au pada Lava Basal Berasosiasi Urat Kuarsa di Lembah Segar, Sawahlunto, Sumatra Barat
DOI:
https://doi.org/10.29303/goescienceed.v7i4.3252Keywords:
Cu-Au Mineralization, Basaltic Lava, Quartz Veins, Micro-XRFAbstract
Evidence of Cu-Au mineralization in basaltic lava from the Segar Valley, Sawahlunto, West Sumatra, indicates heterogeneous elemental enrichment that may not be resolved by geochemical analysis alone. This study characterizes the mineralogy and geochemical composition of basaltic lava and evaluates microscale analysis for identifying localized Cu-Au enrichment. The study integrates petrographic analysis, X-ray fluorescence (XRF), micro-XRF, elemental mapping, and combined elemental mapping of three basaltic lava samples. Petrographic analysis identified quartz, plagioclase, chlorite, epidote, and opaque minerals, with quartz veins indicating hydrothermal fluid interaction. XRF detected Cu at 500–800 ppm in all samples, whereas Au was not detected. Micro-XRF detected Au in all samples and identified the strongest Cu-Au enrichment in V3, reaching 62.778 wt.% Cu and 9.219 wt.% Au. Combined elemental mapping showed spatial proximity between Cu and Au within quartz vein zones in V3. V1 displayed localized linear enrichment, whereas V4 contained up to 69,900 ppm S but relatively low microscale Cu enrichment. These results demonstrate that microscale analysis enhances the identification of localized Cu-Au enrichment. The Cu-Au is interpreted as hydrothermal in origin and spatially associated with quartz veins and fractures, while mineral hosts and deposit classification require further verification.
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