Ore-controlling structural characteristics and prospecting prediction of the Jinshan gold deposit, western Tianshan orogen

The Jinshan gold deposit, located on the southern flank of the Keguqin Mountains in the western Tianshan orogen, is a typical low-grade, large to super-large epithermal system within a continental volcanic terrain. Although its genesis is linked to Late Palaeozoic volcanic-intrusive activity, controversies over ore-controlling structures have constrained deep and peripheral exploration. Through detailed field and outcrop observations, this study identifies multiple Carboniferous palaeo-volcanic edifices (pipes, depressions, necks), overprinted by NS-trending normal faults and conjugate NNW- and NE-trending strike-slip faults. Mineralisation is shown to be jointly controlled by these volcanic edifices, regional fault systems and the unconformity between Ordovician limestone and Carboniferous volcanic-clastic rocks – termed the ‘silica-calcite interface’. A corresponding ore-controlling model highlights favourable exploration targets at this unconformity within structural intersections of subsidiary vents and regional/ring/radial fractures. Subsequent drilling not only confirmed high-grade, thick orebodies (e.g. 6 m @ 3.56 g/t, peak 56.3 g/t) in predicted areas but also revealed anticipated mineralisation types in unexplored zones south of the mine. The study provides a validated structural model for epithermal exploration in similar volcanic terrains worldwide.