Zackly SE porphyry target comes into focus
Last updated 11/16/2018 at 5:10am
PolarX Ltd. Nov. 5 said a high‐resolution aeromagnetic geophysical survey flown this fall over most of the Stellar property, part of the Australian explorer's Alaska Range project, clearly shows the signature of a significant copper‐gold porphyry target at the Zackly SE prospect.
Collecting magnetic data on 50-meter line spacing at an average height of 33 meters above the ground, the helicopter-flown survey provided details of a 7.5-mile (12 kilometers) long structural corridor that encompasses the known Zackly Skarn deposit, as well as the Zackly SE porphyry prospect on the east end and the Mars porphyry prospect on the west end.
This survey has identified several intrusions at Zackly SE that are surrounded by a broad zone of magnetite destruction, a classic signature for large porphyry deposits that is easy to recognize on magnetic geophysical maps.
"Porphyry copper deposits often, but not always, appear as magnetic highs, with alteration halos usually manifested as annular (donut-shaped) or open-ring peripheral magnetic lows," the United States Geological Survey penned in a 2008 report on the characteristics of porphyry copper deposits.
While previous magnetic surveys showed the potential of intrusion at Zackly SE, the higher resolution of this new survey shows numerous magnetic bodies interpreted to represent multiple intrusive phases at this porphyry copper-gold prospect.
The high-resolution magnetic survey also better defines the structural corridor that runs from Zackly SE to Mars.
Lying just east of the midpoint of this structural corridor, Zackly Skarn hosts 3.4 million metric tons of inferred resource grading 1.2 percent (90.4 million pounds) copper, 2 grams per metric ton (213,000 oz) gold and 14 g/t (1.5 million oz) silver, that meets Australian Joint Ore Reserves Committee (JORC) mineral reporting standards.
While expanding this roughly 1,000-meter-long deposit to the east, this year's resource expansion drill program tapped thicker zones of copper-gold mineralization associated with quartz and sericite veining and alteration, indicators that the drilling is vectoring toward porphyry mineralization.
One such hole, ZX‐18020, cut particularly thick and high-grade mineralization about 850 meters east of Zackly Skarn and roughly 2,000 meters west of Zackly SE.
This hole cut 54.6 meters averaging 2.8 g/t gold, 9.4 g/t silver and 0.6 percent copper, including a 0.3-meter (one foot) section averaging 27.3 percent copper, 2.5 g/t gold and 82.5 g/t silver.
The porphyry‐style veins and related copper sulfides tapped in this and other holes drilled around Zackly Skarn, coupled with the geophysical signature, are encouraging signs that a large porphyry orebody could be waiting for discovery at Zackly SE.
"The combination of these results, PolarX' drilling to date and the well‐documented association of skarn mineralization such as Zackly with porphyry copper‐gold systems makes Zackly SE a compelling porphyry target," said PolarX Managing Director Frazer Tabeart.
Zackly Skarn targeting
The higher resolution magnetics will also assist in targeting drills for expansion of Zackly Skarn, which was the primary target of PolarX' 2018 drill program at Alaska Range.
The maps generated from the survey show that the 1,000-meter resource area and the holes that successfully tapped high‐grade skarn mineralization up to 850 meters to the east are located along the northern boundary of this structural corridor.
ZX‐18024, drilled about 40 meters north of ZX‐18020, cut 46.7 meters of 3.1 g/t gold, 0.6 percent copper and 3.3 g/t silver from a depth of 37 meters. This thick intercept included a 21.7-meter higher grade zone that averaged 5.2 g/t gold, 0.8 percent copper and 4.1 g/t silver from 59 meters.
PolarX said the high gold grades and thick, sub‐horizontal geometry of this mineralization encountered in these two holes could be suitable for low cost open‐pit extraction, subject to an economic resource being established through further drilling and feasibility studies.
The company plans to expand this new zone both along strike and down‐dip with additional drilling. This has the potential to rapidly expand the tonnage of the Zackly resource, especially if the thickness and high‐grades of mineralization remain consistent.
This year's drilling also tapped high-grade skarn mineralization about 500 meters west of ZX‐18020 and about 350 meters east of the Zackly Skarn resource.
One such hole, ZX-18023, cut 9.3 meters of magnetite skarn averaging 3.3 percent copper, 2.3 g/t gold and 19.7 g/t silver.
ZX‐18025, drilled about 40 meters below ZX-18023, cut 15 meters of magnetite skarn mineralization averaging 2.3 percent copper, 2.2 g/t gold and 11.9 g/t silver.
The higher resolution magnetic survey shows that the skarn mineralization tapped in these areas about 350 and 850 meters east of the resource are adjacent to magnetic bodies, which will greatly assist accurate drill targeting for resource extensions.
Zackly runs deeper
In addition to finding high-grade mineralization to the east of Zackly, this year's drilling showed the zone runs deeper than what is included in the resource.
One such hole, ZX-18018, cut three zones of copper‐gold mineralization 100 meters below the nearest hole in the resource.
From a depth of 261.6 meters, this hole cut 25.5 meters averaging 0.6 percent copper, 1.5 grams per metric ton gold; and 5.5 g/t silver; 13.9 meters of 0.6 percent copper, 1.1 g/t gold and 4.7 g/t silver from 300.8 meters; and 4.7 meters of 1.3 percent copper, 2.1 g/t gold and 10.6 g/t silver from 326.1 meters.
Higher grade sections of these longer intercepts include 1.4 meters of 3.2 percent copper, 9.3 g/t gold and 38.2 g/t silver from 285.8 meters; and 2.5 meters of 2.3 percent copper, 3.5 g/t gold and 18.5 g/t silver from 326.1 meters.
Assays from seven remaining holes drilled this year are pending.
PolarX is also awaiting results from soil sampling at the Mars porphyry copper-gold prospect; and rock chip sampling from Moonwalk, a Tintina-style gold area in the northern part of the Stellar property.
Editor's Note: This article was updated to more accurately state Zackly SE in association with the easternmost holes drilled in 2018.