Discovery of Au–Ag mineralization by stream sediment and soil geochemical exploration in metamorphic terrain in western Turkey

•We demonstrated that BLEG and − 80 mesh stream, and soil sampling resulted in the discovery of Au–Ag–As mineralization.•Concentration–area (C–A) fractal modeling of raw geochemical data is robust in defining geochemical anomalies.•MMI soil technique demonstrated its superiority over the conventional − 80 mesh soil sampling technique.•MMI technique maximizes drilling efficiency at Cemalcavus by providing precise anomalies related to subsurface sources.•These subsurface resources are proven by the mineralized diamond drill hole Au–Ag intercepts.

Exploration based on BLEG (bulk leach extractable gold) and − 80 mesh stream sediment, and soil geochemical sampling over the Usak-Esme region in western Turkey resulted in the discovery of Cemalcavus Au–Ag–As mineralization. This schistosity-controlled mineralization occurs within sericitized–chloritized almandine–amphibolite facies metamorphic rocks. No mineralization has been reported previously in the area. The concentration–area (C–A) fractal model was applied to the raw data to set threshold values defining background and anomalous classes of uni-element concentrations in BLEG and − 80 mesh stream sediment samples as well as soil samples analyzed by conventional and MMI (mobile metal ion) extraction techniques. The conventional soil geochemical data failed to yield anomalies linked to gold mineralization at or close to the surface whereas the MMI soil geochemical data yielded genuine anomalies that were not only reproducible but were associated with subsurface mineralization. Thus, the MMI technique has maximized drilling efficiency at Cemalcavus Prospect by providing precise anomalies closely related to subsurface sources. As a whole, BLEG and − 80 mesh stream sediment anomalies in combination with MMI soil anomalies followed-up by core drilling led to the recognition of the Cemalcavus Au–Ag prospect although an economically viable mineralization is yet to be discovered.