Stretched to the limit: an extensional detachment setting for the Gosowong epithermal goldfield, Halmahera, Indonesia

Quartz vein hosted low sulfidation high grade Au-Ag ores represent great prizes for miners, yet are notoriously difficult to explore for, due to their narrow hydrothermal footprints and subtle petrophysical signatures. Development of predictive structural models via direct analysis of the vein arrays can also be hampered by non-Andersonian fracture mechanics in the near surface environment, and vein opening modes that do not produce the range of kinematic indicators classically used to decipher the structural history of mesothermal Au deposits. In this study of the world class Pliocene Gosowong goldfield of Halmahera, we circumvent these limitations through the construction of a four-dimensional district scale structural model, based on analysis of lithostratigraphic architecture. The method allows us to project controlling structures beyond the limits of the mineralised vein arrays, identify lithologic and hydrologic controls on vein propagation and alteration styles, and to link the geometrically diverse ores that occur throughout the district.