Hannan Discovers a New Thick Style of High-Grade Sediment Hosted Copper in Peru - Seite 2

The new discovery at San Martin West was made during follow-up of BLEG samples during 2023. To date mineral prospecting has been focusing on surface sampling and mapping in ravines and systematic soil samples on topographic ridge lines. Outcropping is scarce in the area and the whole area is covered by dense vegetation.

The mineralization is hosted by a 10 m to 30 m thick stratigraphic unit composed of medium to coarse grained sandstone and sedimentary breccia which has been traced for >2.3 km that remains open along strike to the North. Figure 2 shows a stratigraphic correlation diagram showing results from the 12 channels across >2.3 km of strike. All channels are exposed on surface and the host rock is partially to strongly leached of copper minerals.

The unit hosts rich disseminated iron oxide concentrations after carbonates (siderite and ankerite). The concentration varies from 10% to >50% of the volume of the host rock. Stratigraphically it is situated some 50 m from the contact to the Cretaceous Cushabatay Formation. Both the hanging-wall and the foot-wall of the sandstone is composed of fine-grained red siltstone of the Sarayaquillo Formation.

Carbonate concretions may form under a variety of geological conditions. However, the mapped outcrop shows a composition and texture similar to mapped paleoflows of ancient carbon dioxide (CO₂) driven gas systems (Loope 2015). Therefore, Hannan interprets the concretions to be remnants of methane and CO₂ rich gases that have participated carbonates in a water saturated host rock. Reduction of the host rock occurred during gas and host rock interaction resulting in bleaching of a red oxidized sandstone to the current white and reduced sandstone host.

Supergene copper mineralization is common and dominated by neotocite, tenorite and malachite. Hypogene copper minerals are dominated by chalcocite, but locally bornite, chalcopyrite and pyrite are observed in hand samples. Copper sulfides have precipitated on the rims of carbonate concentrations and on organic carbon clasts within the host rocks (Figure 4). Paleomicrobial activity feeding on the primary carbonate concretions may have formed an important part of the trap for the oxidized copper rich fluids and explain why chalcocite is rimming the carbonate concretions.