Geochronology and geochemistry characteristics of the volcanic rocks in Pangkuam gold deposit area, Northwestern Laos and its implication for gold exploration

Pangkuam gold deposit is a large gold deposit that has been detailedly investigated in northwestern Laos and shows the potential becoming a super-large mineral deposit.It is of great significance to carry out research on this deposit and its surrounding area for understanding the formation and exploration direction of gold deposit in NW Laos.In this study, we investigate the petrological, geochronological and geochemical studies of volcanic rocks in Pangkuam mining area.The results show that the LA-ICP-MS zircon U-Pb ages of the basalt, chlorite hornblende andesite, and sericite hornblende andesite is 304.5 ±3.9 Ma, 309.4 ±3.1 Ma, and 314.4 ±3.6 Ma, respectively, and these ages belong to the middle to late Late Carboniferous.These volcanic rocks show low TiO₂, Ni, Cr, and high Al₂O₃ content.In addition, they are enriched with LREEs and LILEs but depleted in HFSEs.These geochemical characteristics tested by XRF and ICP suggest that these samples are a set of calc-alkaline andesite-shoshonite rocks and exhibit a geochemical affinity to active continental marginal arc volcanic rocks.In summary, these samples may be products of subduction and closure of the Loei ocean.The exist of intermediate-basic volcanic rock series of the Late Carboniferous may indicate that the formation of gold deposit in NW Laos needs further study, and peripheral prospecting may need to focus on more volcanic rocks.