Colorback Project – Carlin Style Gold
Colorback Project is located 10kms southwest of the township of Crescent Valley and is accessed directly via paved state route 306 being some 40km’s south of interstate highway 80. Elko, the closest major town is located 90km to the northeast and is reached by travelling northwards along state route 306 then eastwards on interstate highway 80 for a total travel time of approximately 1 hour. Given the proximity to very large mines the Colorback Project is accessed by, and located near, well established infrastructure.
The Colorback Project is in the heart of the prolific northwest trending Battle Mountain Trend of central Nevada and is prospective for Carlin style gold deposits. The Colorback Project consists of 42 contiguous 20 acre claims and covers an area of 3.4km2.
The Battle Mountain Trend is a remarkable gold province that hosts several world class gold deposits with a total production and reserves of more than 100Mozs Au. The giant Pipeline deposit (20Mozs Au), Cortez Complex (15Mozs Au) and Barrick’s recent Goldrush and Fourmile discoveries (+15Moz Au and growing) are all located within 25km’s of the Colorback Project.
Sierra Nevada’s Colorback project displays several key similarities to the nearby world-class Carlin gold mines such as the Pipeline deposit and the Cortez Complex deposits. Importantly, controlling structures from these deposits transect and intersect within the Colorback Project. Through its data acquisition and exploration program Sierra Nevada has identified large scale fertile structures with the potential to host a significant Carlin style mineral system.
The main target for future exploration remains where structures intersect Lower Plate carbonate-bearing rocks below the current depth of drill holes. The Colorback project displays several key features like the nearby Carlin-style mineral deposits in the Battle Mountain trend (i.e., Cortez and Pipeline deposits) which include:
- NW and NE oriented structures, associated with elevated Au, As, B and Hg values in rock chip and soil samples, cut the project, these structures have influenced the location of gold mines elsewhere in the district.
- An embayment in the gravity data is suggestive in proximity to Lower Plate stratigraphy.
- A single deep hole by a previous explorer (drill hole VIT 06-01) intersected a zone of de-calcification, which is a typical alteration feature of Carlin-style Au mineralisation which reported 4.57m at 0.64g/t Au from 666m.
- Ground magnetic data suggests the presence of an intrusion at depth in the centre of the tenement possibly due to the local uplift of the sequence by the Roberts Mountain Thrust.
- Drill holes have intersected carbonaceous units which are interpreted as the lower part of the Upper Plate sequence, which suggest proximity to the highly prospective Lower Plate units.
Additionally, rock-chips samples returned 18.15g/t Au from a fault zone proximal to the outcropping Tenabo intrusion, suggest potential for Gold Acres style Au mineralisation.
Sierra Nevada’s exploration datasets clearly defines gold bearing structures suitable for controlling the deposition of a major carlin style gold system in this highly endowed location.
During 2022 Sierra Nevada completed five reverse circulation (RC) holes for 378m at Colorback and results confirmed the presence of near-surface gold mineralisation, verifying historic drilling that outlined zones of near surface oxidised gold mineralisation. CBRC001 returned 29.26m at 1.30g/t Au including 7.32m at 3.61g/t Au from 7.32m depth.