Summary:
Gold and silver mineralisation at Cap Oeste is hosted by the northwest trending Cap Oeste Breccia Fault, which dips 75° to 90° to the southwest.
The drilling to date has defined a high-grade shoot, approximately 130 m long and 12 m to 15 m wide, situated in the interpreted southeast extension of the Bonanza Fault. The high-grade ore shoot pitches steeply to the west-northwest over an approximate 120 m vertical interval, extending from 135 m to 255 m vertically below surface as currently defined by the drilling to date. Mapping, trench sampling and drilling has confirmed that the high-grade shoot is overlain by a broader (e.g. 20 m thick) zone of more diffuse lower grade, high Ag/Au ratio mineralisation and trace element anomalism.
The highest-grade Au-Ag mineralisation is hosted by a distinctive suite of sinuous to weakly bifurcating breccia, comprising argillic altered characteristically rounded fragments of volcanic host rock in a sulphide-rich milled breccia matrix of fine-grained grey quartz, illite, and carbonaceous material. Precious metals occur as native metal, alloys and sulphides, in close association with base metal sulphides, pyrite, and arsenopyrite. These zones of very high-grade Au-Ag mineralisation are referred to by Patagonia Gold PLC (PGD) as ‘hypogene’ mineralisation, or more commonly ‘COSE’ style mineralisation, as a reference to the nearby COSE Au-Ag mineralisation style to the southeast of Cap Oeste.
PGD geologists have defined several broadly defined successive types of mineralisation at Cap Oeste (CAM, 2012). The individual types are defined according to their respective locations in relation to the Bonanza Fault or Esperanza Faults. Cube has labelled two main zones of mineralisation based on the 3D interpretation as the Bonanza Fault (“BZ”) breccia mineralisation and the Esperanza Fault (“EZ”) quartz vein style mineralisation.
The Cap Oeste Mineral Resource area has dimensions of 1,700 m (strike length) by 200 m (maximum width of combined mineralised zones) and 400 m (maximum vertical depth below surface). The overall form of the mineralised envelope of the Bonanza Zone at Cap-Oeste in section is planar and broadly sigmoidal with an average dip of 55° SW, with local variations between 40° and 80°. The overall planar geometry of the mineralised section of the Esperanza Fault zone which dips steeply (75-85°) to the NE was partially tested by ‘step-back’ holes designed principally to test the Bonanza Fault at depths greater than 150-200 m RL.
Mineralisation at Cap Oeste is also assigned to the low sulfidation type, based on the presence of fine-grained replacement quartz and adularia, widespread illite alteration, bladed textures indicative of hydrothermal boiling, and a mineral assemblage dominated by marcasite, arsenopyrite and silver-bearing sulphosalts. The presence of anomalous copper and molybdenum associated with higher-grade Au-Ag mineralisation suggests a component of magmatic-derived fluid.
The Cap Oeste deposit occurs predominantly as hydrothermal breccia, in combination with replacement, veinlet and disseminated styles of mineralisation, rather than as one or more discrete quartz veins.
Although the Patagonia has commenced extraction of minerals at the Cap-Oeste mine, the Patagonia does not have defined mineral reserves as defined under Regulation S-K, subpart 1300 and therefore mining property is considered to be in the exploration stage.