Gold mineralisation along the Nam Xiang Fault, Vieng Kham project, northeast Laos

The Palaeozoic rocks of northeastern Laos are an attractive target for gold explorers due to the complex tectonic history and lack of past exploration in the region. Alluvial workings along the Nam Xiang River and its tributaries have highlighted the potential for gold mineralisation in the Vieng Kham Region. The Nam Xiang River follows a regionally extensive NNE striking thrust fault. Adjacent to the Nam Xiang Fault, the dip of the main foliation steepens and in many places the stratigraphy is overturned as a result of this faulting.

United Minerals and Mining Company has conducted regional exploration program to explore for gold. This included stream sediment and rock-chip sampling and airborne geophysics. Geochemical anomalies were followed-up with more detailed exploration including geological mapping and soil sampling. Despite the relatively deep weathering profile, gold mineralisation is associated with a low-level, but well-defined gold in soil anomaly. Drilling has shown that gold mineralisation occurs on structures and fabrics parallel to the main Nam Xiang Fault. The highest gold grades are associated with brecciated sandstones that have experienced strong carbonate alteration. This suggests that the late stage structures such as the Nam Xiang Fault are the major control on gold mineralisation in the region.