Brestovac Exploration Permit
Highlights
- Exploration Permit located only 3 km south of world class Bor copper-gold mining district
- Reservoir discovery of high-grade epithermal gold system in Corridor along strike length of 320 meters, with potential for further extensions
- Best intercept 16.90 meters at 13.04 g/t gold
- Favourable geology and structure extends from the Bor district into the Permit, with excellent potential for porphyry copper-gold mineralization on 4 km strike extension of the Bor fault
Background
The Brestovac Exploration Permit is located within the central zone of the Timok Magmatic Complex, in the Serbian section of the East European Carpathian-Balkan Arc. Total metal endowment of the known ore deposits within the Bor -- Majdanpek zone in the Timok Magmatic Complex, including past production, was estimated by Jankovic et al. (1998) to be over 20 Mt copper and 1000 t gold. The Bor-Majdanpek mineralization is Cretaceous-age high-sulphidation epithermal and porphyry type copper-gold, with the main control the Bor fault that extends along the eastern side of the Timok Complex.
The Brestovac Exploration Permit lies 5km south of the Bor copper-gold mine, which has an endowment of 7 Mt of copper and 300 t of gold and current reserves and resources are over 200 Mt at 1.5% Cu and 0.8 g/t Au. Regional geophysics, geological mapping and satellite image analysis show that a 6 km strike length of the Bor fault, which is the main control of mineralization in the region, passes through the Brestovac Exploration Permit where it is also the focus of alteration and mineralization.
REO filed a 43-101 Technical Report on the Brestovac Exploration Permit in January 2007.
Geology and Mineralization
The geology of the Permit area is dominated by Cretaceous andesite volcanics and volcaniclastics, with local dacite intrusives, overlain by Upper Cretaceous and Miocene sedimentary rocks. The Permit area is structurally complex, with both high-angle faults as well as thrust faults. Aster Image analysis and geological mapping demonstrate the structural continuity from the Bor copper-gold district southwards through the Brestovac Exploration Permit.
The Brestovac Sector of the Permit contains historic surface workings for gold (now obscured by vegetation), replacement zinc-copper-lead mineralization hosted by marls that was explored by an adit and blind shaft (no longer accessible), and occurrences of copper mineralization similar to the Bor-type as well as veins of quartz-pyrite-chalcopyrite-sphalerite mineralization.
REO has discovered high-grade epithermal gold in the "Corridor" zone, and developed excellent targets for porphyry copper-gold mineralization in favourable geology along the Bor fault system.
Title and Area
The Brestovac Exploration Permit was issued to SEE d.o.o. on 15 December 2004, and covers 25.5 sq. km.
Exploration Status
Epithermal Gold Mineralization in the Corridor
Initial work focused on validating the reported gold mineralization encountered in a 1970 drill hole near Brestovac. This included a drill hole in the same location as an earlier hole with reported gold and copper intercepts (BN-01). Concurrently geological mapping, stream sediment sampling, soil sampling, and rock-chip sampling from outcrops and float was undertaken, followed by detailed ground magnetic and IP/resistivity surveys. This work identified the "Corridor" of anomalous geochemistry and resistivity extending SW for about 300 meters from the gold mineralization discovered in drill hole BN-01.
The "Corridor" has been tested over a strike length of 320 meters by 14 drill holes (BN-01 -- 14; total 1937 meters), all of which intersected gold mineralization and associated alteration, with best intercept of 16.90 meters at 13.04 g/t gold in BN-05 (see list of drill holes with analytical data of the best intersections). In addition, carbonate replacement zinc mineralization was intersected in BN-01 - BN-05, BN-09 and BN-11. Fiver deeper holes (BN 15 -- 19; total 1898 meters) were drilled to test geophysical targets to the south of the Corridor as well as extensions to depth beneath and to the northeast of the Corridor zone. The most significant of these was BN-19, which intercepted a massive sulphide zone with 24.8 meters at 0.33 % copper and 0.16 grams per tonne ("g/t") gold about 250 meters northeast of the Corridor, and supports the potential to extend the strike length of the zone as is also suggested by historical data.
Alteration in the Corridor includes argillic and sericitic facies, with a carbonate overprint and local silicification, quartz veining and development of vuggy silica. Ore mineralogy is dominated by disseminated pyrite, accessory sphalerite and galena, and very rare free gold - electrum.
The gold mineralization in the Corridor is best developed (grade and thickness) in matrix-rich volcaniclastic rocks and hydrothermal and tectonic/fracture breccias, probably associated with high-angle faults. REO considers that the high-grade epithermal gold mineralization and associated alteration are polyphase, and controlled by both lithology (matrix-rich volcaniclastic rocks and breccias) and structure (high-angle faults). The controlling faults were active over long periods of time, resulting in multiple phases of alteration and the gold mineralization, which was probably a relatively late stage event.
Porphyry Copper-Gold Targets
Aster mineral mapping and structural interpretation demonstrated the structural continuity of the Bor Fault system from the Bor porphyry district through the Brestovac Permit. Geological mapping has identified the favourable volcaniclastic lithologies for porphyry-style mineralization and, in the north of the Permit area, encouraging alteration and mineralization outcrops proximal to the Bor Fault zone. Strongly anomalous copper-in-soil values are contiguous with the dacite mapped to the south of Brestovac village, which is associated with a prominent E-W structure, and close to copper mineralization (potentially Bor-type) outcropping in a quarry to the south of Brestovac village.
