The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
Discovers further evidence of a deeper gold-copper porphyry North of 60 Mining News - December 20, 2023
Of the 17 holes drilled this year at the Bronson Slope deposit, 15 encountered significant gold-copper mineralization.
Seabridge Gold Inc. Dec. 20 reported that its 2023 Iskut drill program has expanded the known Bronson Slope copper-gold deposit on its Iskut project in Northern British Columbia and confirmed an extensive area of magmatic-hydrothermal alteration sourced from an apparently very large porphyry mineral system at depth.
Located about 30 kilometers (19 miles) west of Seabridge's world-class KSM mine project, Iskut is home to the 1980s-era Johnny Mountain gold-silver-copper mine. Seabridge has focused much of its exploration at Iskut on discovering a large porphyry intrusive responsible for the high-grade skarn that was mined at Johnny Mountain.
The Bronson Slope target adjacent to Johnny Mountain hosts 187 million metric tons of measured and indicated resource averaging 0.36 grams per metric ton gold and 0.12% copper, based on drilling carried out prior to Seabridge's 2016 acquisition of the Iskut property.
Seabridge's 2022 drilling at Bronson Slope discovered a quartz-magnetite breccia pipe in the area of the Bronson Slope resource. SGS-22-05, the first hole to encounter this breccia pipe, cut 88.5 meters averaging 0.7 grams per metric ton gold, 0.28% copper, and 4.1 g/t silver.
The 2023 Bronson Slope program was designed to simultaneously evaluate the potential to expand the Bronson Slope resource adjacent to the breccia pipe and test for a deeper porphyry source. Last week, Seabridge reported that its first drilling at the Snip North target near Bronson Slope encountered significant copper-gold mineralization.
Of the 17 holes drilled this year at Bronson Slope, 15 encountered significant gold-copper mineralization. Some of the highlights from the 2023 program include:
• 99 meters averaging 0.61 g/t gold, 0.03% copper, and 3.4 g/t gold from a depth of 72 meters in hole SBS-23-11.
• 10 meters averaging 6.36 g/t gold, 0.02% copper, and 4.7 g/t silver from a depth of 800 meters in hole SBS-23-11.
• 107.5 meters averaging 0.48 g/t gold, 0.03% copper, and 12.7 g/t silver from a depth of 742.5 meters in hole SBS-23-13.
• 437.3 meters averaging 0.36 g/t gold, 0.03% copper, and 6.1 g/t silver from a depth of 382.6 meters in hole SBS-23-17.
• 551.8 meters averaging 0.36 g/t gold, 0.02% copper, and 2.6 g/t silver from a depth of 438.4 meters in hole SBS-23-18.
• 252 meters averaging 0.87 g/t gold, 0.02% copper, and 29.2 g/t silver from a depth of 168 meters in hole SBS-23-19.
• 341.5 meters averaging 0.36 g/t gold, 0.05% copper, and 11.4 g/t silver from a depth of 344.9 meters in hole SBS-23-20.
• 320.4 meters averaging 0.49 g/t gold, 0.03% copper, and 3.1 g/t silver from a depth of 490.7 meters in hole SBS-23-21.
• 120.5 meters averaging 0.58 g/t gold, 0.02% copper, and 2.7 g/t silver from a depth of 150.2 meters in hole SBS-23-22.
"One of the concepts that led us to acquire the Iskut Project was the expectation that a larger epithermal mineral deposit could potentially be preserved at Bronson Slope," said Seabridge Gold Chairman and CEO Rudi Fronk. "This expectation has been confirmed but as we have learned more about this occurrence, we have become more convinced and excited about the potential to find its source porphyry."
The company reports that the 2023 drilling encountered an upper zone hosted by a Triassic sedimentary section characterized by hornfels, bedded arkose, and mudstone; and a lower zone of intensive sericite-pyrite-carbonate where gold grades are extensive.
Narrow bands of nearly massive sulfides containing pyrite, sphalerite, chalcopyrite, galena, and bornite that likely represent feeder structures were encountered in the lower zone. This discovery represents the first massive sulfide mineralization similar to an enigmatic train of large, massive sulfide boulders with ultra-high base and precious metal grades found on the surface.
Seabridge says the deeper drilling it carried out this year to identify the porphyry source of the breccia pipe at Bronson Slope cut narrow intervals of intrusive rocks at depth but has yet to encounter the source. The company, however, continues to believe all the mineralizing phenomena at Bronson Slope are the result of a specific magmatic porphyry intrusion that gave rise to the breccia pipe and whose fluids evolved to generate the overlying epithermal system, including its massive sulfide occurrences.
"Next year's program will aim to integrate the upside at Bronson Slope with our hypothesis of a regional structurally-controlled porphyry district encompassing the entire Iskut project," said Fronk.
Seabridge plans to incorporate the results from its drilling into an updated resource estimate for the Bronson Slope deposit.
Over his more than 16 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.
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