The Central zone of Iceberg contains a mix of near surface oxide and sulfide mineralization over a large footprint and hosts gold in multiple horizons. The Central Zone has the intriguing mix of gold mineralization in both the Devonian Horse Canyon and Wenban formations as well as the overlying volcanic rocks. Exploration to expand the mineralization footprint is ongoing as only widely spaced drilling has tested the western extent of mineralization.
The Central Zone of Iceberg has a ~30-100 m thick section of mafic volcanics overlying ~40-60 m of Tertiary sediments and tuffaceous volcaniclastics with a ~30 m thick coarse grained conglomeritic bed at their base. Below the Tertiary section are Devonian carbonates of the Wenban Formation and strongly silicified clastic sediments of the Devonian Horse Canyon Formation. At least two generations of igneous intrusives are present in the Devonian rocks one of which is correlative with a small Cretaceous stock just to the east of the Central Zone. Both intrusives are associated with extensive calc-silicate skarn alteration in the Wenban Formation. The largest structure in the Central Zone is the north-northwest trending, west dipping Iceberg Fault that cross cuts west-southwest striking, south dipping normal faults. Both the volcanics and the Paleozoic sediments in the hanging wall of the Iceberg Fault have a distinct west dip versus the eastern dip to the exposed carbonates on the footwall side of the fault. Central Zone Mineralization is hosted in mafic volcanics, the Tertiary sediments, and in the Horse Canyon Formation. Gold mineralization in the mafic volcanic rocks is disseminated and concentrated in argillized flows or vesicular flow caps. The highest grade mineralization is in the Tertiary sediments, concentrated in the basal conglomerates, and is associated with strong silicification and oxidation. The lower mineralized horizon is in jasperoid breccias in the lower Devonian Horse Canyon Formation.