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Shallower Iskut porphyry target emerges


Last updated 1/4/2019 at 5:11am

Seabridge gold copper exploration drilling Golden Triangle British Columbia

Seabridge Gold Inc.

Drilling carried out at Iskut in 2017 targeted a gold-bearing epithermal system beneath the Quartz Rise lithocap, an alteration zone that is often found above porphyry-type gold-copper deposits.

Seabridge Gold Inc. Dec. 18 said it has encountered the hallmarks of a large copper-gold porphyry system at its Iskut project in northwestern British Columbia.

"We acquired Iskut in 2016 because it showed clear evidence of a large porphyry system similar in age and geology to our KSM project 30 kilometers (19 miles) to the east," said Seabridge Gold Chairman and CEO Rudi Fronk.

Quartz Rise was the first porphyry target at Iskut tested by Seabridge.

Drilling carried out in 2017 targeted a gold-bearing intermediate sulfidation epithermal system beneath the Quartz Rise lithocap, an alteration zone that is often found above porphyry-type deposits.

While this drilling cut several narrow, discontinuous intervals of high-grade gold it did not hit the mineralization sought.

Seabridge's maiden drill program at Iskut's Quartz Rise target in 2017 cut several narrow, discontinuous intervals of high-grade gold.

A subsequent 3D induced polarization geophysical survey, together with detailed geological mapping and sampling of available rock faces is helping to target this year's drilling. This includes exceptional gold results from cliff face sampling that appear to correspond with a favorable induced polarization (IP) chargeability anomaly under Quartz Rise.

Drilling tested the dip projection of high-grade surface samples in an area hosting coincident IP chargeability and resistivity anomalies. Results confirmed that much of the Quartz Rise lithocap had been eroded, leaving little opportunity for a sizeable high-grade epithermal occurrence in this area.

"Our view was that the Iskut porphyry was likely too deep to be our primary target and we therefore focused initially on finding a lithocap-hosted epithermal top of the porphyry system. We have since learned that this target is probably not viable in the Quartz Rise area due to erosion. However, we are very excited to find that this same erosion has given us the opportunity to explore for another KSM-style porphyry system located much closer to surface than we anticipated," said Fronk.

Two holes drilled this year discovered a hydrothermal breccia (diatreme) that Seabridge says confirms that a porphyry source for the lithocap is nearby.

Iskut Quartz Rise porphyry copper gold map target diagram

Diatremes are explosive volcanic vents produced in a solid rock structure by the energy from expanding fluids and gases evolving off magmas. Diatremes are commonly found above and adjacent to porphyry mineral systems which are their source of heat and fluids.

Seabridge says extensive review of the available data indicates the source for the diatreme is south and southwest of Quartz Rise, where glacial erosion has exposed rocks deeper in the mineralizing system. This erosional window provides the opportunity to explore into the heart of the porphyry system with much shorter drill holes from a lower elevation.

"This is the target we will now pursue at Iskut," said Fronk.



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