A programme combining reverse circulation and core drilling for up to 50,000 meters of drilling will be carried out in several phases


Sonoro plans expanded drilling programme at Cerro Caliche. (Credit: Steve Bidmead from Pixabay)

Sonoro Metals announces the completion of a comprehensive technical assessment on the 17 zones of gold mineralization identified to date at its Cerro Caliche project in Sonora, Mexico. The purpose of the assessment was to evaluate the potential for a material increase in the current 201,000 oz AuEq resource as well as the potential to delineate further resources throughout the mineralized zones. A program combining reverse circulation and core drilling for up to 50,000 meters of drilling will be carried out in several phases.

The next phase, Phase III, targeting approximately 10,000 meters of drilling, will commence in March 2020.

In Phases I and II of the drilling program, a total of 96 holes totaling 10,328 meters were drilled and assayed for an average drill hole length of 107.6 meters, all inclined. The combination of historic and current exploration drilling totals 23,679 meters in 212 drill holes, in addition to more than 6,000 surface samples. Drilling to date has outlined shallow, bulk tonnage gold mineralized zones with grades similar to operating heap leach mines in the region.

In addition to the continuation of reverse circulation drilling, core drilling will also be employed during Phase III to more accurately determine the dimensions of the gold-mineralized geologic structure. These mineralized structures are common within the shallow gold-silver resource partially defined by the recent reverse circulation drilling.  Furthermore, core drilling will be employed to explore the potential for higher-grade gold mineralization in the vein zones that structural analysis asserts may be present at greater depths within the veins. In general, mineralization models indicate that deeper parts of low sulfidation epithermal deposits are more likely to contain higher-grade precious metals.

Silver/gold ratios vary with physical elevation within the mineralized vein zones. These silver/gold ratios can be used to determine the vertical position of specific mineralization within the structure. An example of this is found in drill hole SCR-044 in the El Colorado zone, where the mineralized intercept at the lowest elevation contains 12.2 m of 11.3 g/t AuEq and a silver/gold ratio of 0.4. This contrasts with drill hole SCR-057 in Veta de Oro, where an intercept located at a 150-meter higher elevation recorded 6 m of 132.6 g/t Ag and 2.5 g/t Au, resulting in a silver/gold ratio of 54. Other metal ratios, mineralogy, and physical characteristics relating to elevation are being investigated to select higher-grade targets throughout Cerro Caliche’s large database.

“We are particularly encouraged by the fact that the initial 201,000-ounce gold resource is situated within a surface area comprising under 10% of the total property area,” said Kenneth MacLeod, President and CEO of Sonoro. “Also, only 30% of Cerro Caliche’s known regions of potential gold mineralization have been drilled. Essentially all of the 17 zones of gold mineralization so far identified at Cerro Caliche remain open to expansion along strike and new zones of gold mineralization are currently being discovered in previously unexplored regions of the property.”

The proposed drilling program has been designed to optimize the current data from each of the zones of gold mineralization. This ensures that the placement and angulation of the new holes will likely contribute to a potential increase in the size of the resource and develop a greater understanding of the geological structure within the shallow zones and to depth. Drill holes will be placed at a maximum spacing of 100 meters to enable proper classification of the results. Sequencing of drilling for each individual zone is currently being finalized. For more details on the proposed drilling program

Source: Company Press Release