The 4,959Ha Bramaderos gold-copper porphyry project is located in Loja province, a 130km (2 hour drive) from the provincial capital city Loja, and west of the town of Catacocha. Easy access is provided by the sealed Pan American Highway which crosses the western part of the concession.
The property is an incorporated joint venture between Sunstone Metals and Cornerstone Capital Resources, a TSX-V listed company with a long history of exploration operations in Ecuador, including the discovery of the Cascabel copper-gold porphyry in joint venture with Solgold Plc.
The Bramaderos Project is held by La Plata Minerales (‘PLAMIN’) of which Sunstone metals has a 87.5% ownership and Cornerstone a 12.5% ownership. Sunstone is fully funding all activities at Bramaderos and Cornerstone is loan carried to production. Sunstone is also managing all exploration activities at Bramaderos through its Ecuadorian team.
Bramaderos lies at the northern end of a Cretaceous age volcanic arc that extends south into Peru, and is proximal to Palaeocene to Eocene and Miocene age volcanic arcs in southern Ecuador that overlie the eastern margin of the Cretaceous arc. The property is underlain by Cretaceous calcalkaline volcanic andesites, dacites, coeval tuffs and associated volcanic sediments of the Pinon and Celica Formations. These are dominantly marine sequences that are remants of a volcanic arc that developed on the Andean margin during the Cretaceous period. The Celica Formation is intruded by members of the Tangula Batholith of Cretaceous age, and by potentially younger Tertiary age (although undated) quartz diorite intrusions.
Bramaderos was sporadically explored during the periods 1970 to 1984, 2001 to 2002, and 2004 to 2007. Gold mineralization was first discovered by a United Nations Development Program and Spanish Aid Mission in 1970 during regional stream sediment surveys. Anomalous copper, lead, zinc and molybdenum were identified in streams and soils in the area known as Rio Playas. Subsequently, when Ecuanor S.A. explored the area in 2001-2002 the area was known as Curiplaya. Ascendant Exploration explored the Curiplaya property between 2004 and 2006. Both Ecuanor S.A. and Ascendant Exploration undertook extensive exploration programs that culminated in drilling at the Bramaderos, Melonal and Porotillo porphyry prospects and surrounding area.
Historical soil surveys and geological mapping identified at least four, north-northeast aligned, and partially overlapping centres of porphyry gold-copper mineralization associated with quartz stockwork zones and potassic-altered quartz-hornblende diorite intrusions. Porphyry-style gold-copper mineralization was found associated with quartz and quartz-magnetite vein stockworks and breccias hosted by a cluster of quartz diorite porphyries that show typical gold-dominated porphyry alteration and mineralization patterns. Argillic/phyllic alteration haloes around the centres of porphyry mineralization surround, merge and overprint the centres of potassic alteration. An extensive, 5km by 1-2km, gold and copper (+/- molybdenum) soil geochemical anomaly located in the central part of the property has been only partially tested by trenching and diamond drilling.
A total of 883 rock and 1315 soil samples were collected in the most recent historic phase of exploration by Ecuador Gold S.A., including 17 trenches dug and channel sampled at Bramaderos, Melonal and Porotillo, 19 trenches dug and channel sampled at West Zone, 31 line kilometers of Ground Magnetic and Induced Polarization (IP) surveys carried out, and a total of 10,416m of diamond drilling performed to test some of the anomalous areas.
Significant results in historical drilling include 257m @ 0.6g/t gold and 0.14% copper in hole CURI-03 (inc 76m @ 0.9g/t Au and 0.2% Cu from 53m) within the Brama prospect.
The porphyry gold-copper mineralization encountered by historic and recent drilling at the Brama prospect and copper-gold-molybdenum soil and rock chip geochemical data, indicate that Bramaderos has the potential to host significant gold and copper mineralization.
The Limon gold-copper prospect, whilst early stage, has the appropriate scale of surface alteration, and gold plus copper grades from limited rock chip sampling to date, to present a second compelling porphyry target with high tonnage potential. A first phase of drilling has been completed and will be followed by a second phase.
Furthermore, the Espiritu epithermal vein and breccia prospect has demonstrated very high silver grades at surface and in preliminary drilling.
While the Brama target is a prime focus, Limon and other porphyry targets, plus the Espiritu high grade epithermal target have received minimal exploration despite good potential to deliver significant discoveries.