Astro Plutonic Complex

Target Type: Intrusion-hosted Gold
Location: Yukon & Northwest Territories, Canada

Overview

The Astro Plutonic Complex (APC) in the eastern Tombstone Gold Belt at the Yukon – Northwest Territories border is 20 km east of the Rogue Plutonic Complex of Snowline Gold Corp. The APC is defined by four mid-Cretaceous (90-98 Ma) felsic intrusions belonging to the Mayo, Tombstone and Tungsten Suites. The intrusions are known from west to east as the Keele Pluton, the Kelvin Stock, the Canol Trail Stock and the Border Pluton.

Historically, the western part of the Tombstone Gold Belt was believed to be gold-rich, while the eastern part of the Belt was believed to be tungsten-rich as it is host to the Cantung and Mactung tungsten deposits. However, the discovery of the high-grade and discrete Valley occurrence by Snowline Gold in 2021 has transformed the understanding and re-invigorated the exploration potential for gold in the eastern part of the Belt.

Rackla, an early mover in the eastern part of the belt, has acquired six properties including two properties that make up the Astro Plutonic Complex – Astro East in NWT and Astro West in Yukon. The mid-Cretaceous intrusions in the APC exhibit the classic geological, geochemical and geophysical signatures of a RIRGS setting.

Property Status

The Astro East property is comprised of 26 NWT mineral claims for a total of 19,922 hectares. The Astro West property is comprised of 400 Yukon quartz claims for a total of 8,218 hectares. The claims are owned 100% by Rackla and are subject to Royalty agreements with three different entities, each at a 2.5% NSR.

Exploration History

Astro East

There is no record of any exploration activity on the Astro East property prior to 2017. In 2017, a joint venture between Newmont and Evrim Resources Corp. conducted a reconnaissance exploration program in the Misty Creek Embayment in Northwest Territories with the target model being a Carlin-type gold system. The program included a large, generative Bulk Leach-Extractable Gold survey (BLEG) along the border region of the NWT covering an area measuring 200 km x 80 km. This survey identified the Astro East area as strongly anomalous for gold. Follow-up stream sediment sampling defined a ten-kilometre-long corridor of anomalous gold.

In 2018, the joint venture completed infill stream sediment sampling, contour and grid soil sampling, geological mapping, prospecting and trenching. In 2019, the joint venture conducted an airborne magnetic survey and reverse circulation drill program consisting of 11 holes for 1,111 meters. Highlights from this work were a Trench at the Radio showing that contained 17.7 g/t gold over 30.0 m, a trench at the Microwave showing that contained 3.6 g/t gold over 18.0 m and 0.67 g/t gold over 7.6 m in RC hole RAD19-02.

Newmont relinquished its option in the project in 2020. Later that year, Evrim merged with Renaissance Gold Inc. to become Orogen Royalties Inc. In the fall of 2022, Rackla Metals optioned the Astro property from Orogen.

In 2023, Rackla conducted a comprehensive exploration program that focused on the Border Pluton and anomalous RIRGS indicators. The program consisted of an airborne geophysical survey, ground magnetic and VLF-EM surveys, stream sediment and soil sampling, prospecting and drilling of 12 holes for a total of 2,000 m. The drill program returned gold intercepts of 3.46 g/t gold over 3.05 m in hole AST-007, 0.261 g/t gold over 34.12 m in hole AST-004 and 0.492 g/t gold over 12.44 m in hole AST-005.

Astro West

The Astro West exploration history has been divided between two separate project areas, the HIT project focused on the Canol Trail Stock, and a variety of operators exploring the Kelvin Stock under a number of different project names (now known as the SER claims).

The exploration history at HIT is mostly defined by scattered, short exploration programs focussed on a variety of commodities, dependent on market conditions. The first documented exploration was for tungsten in 1970-71 by Cyprus Anvil Mining Corporation. This was followed in 1982 by a joint venture between Max Mining and Canada Tungsten, who continued exploration until the end of 1984.

In 1998, prospector B. Kreft conducted a short prospecting program following up on a regional geochemical survey (RGS) stream sediment gold anomaly. The program returned some significant results including a channel sample at the Gully showing with 7.85 g/t gold over 7.0 m, a grab sample at the Mehitabel (Discovery) showing that contained 20.51 g/t gold and a stream sediment sample that contained 10.834 ppm gold. Kreft staked 8 Quartz claims to cover the showings on behalf of Eagle Plains Resources Ltd.

In each of 1999, 2006 and 2009, Eagle Plains conducted short programs of prospecting, rock, stream sediment and soil sampling and drilled two diamond drill holes at the Gully showing. The best intercept from drilling was 2.57 g/t gold over 0.9 meter in brecciated and pyrrhotite mineralized limestone. Soil sampling returned up to 1.097 ppm gold and rock sampling returned up to 3.85 g/t gold from the Ridge Zone.

In 2011, Eagle Plains optioned the property to Aben Resources Ltd, who later that year conducted an airborne geophysical survey, geological mapping, stream sediment, rock, and soil sampling. Highlights from this program include 2.0 g/t gold from a 1.0 m chip sample at the Mehitabel showing, 0.6 g/t gold from the Babe Ruth showing, and samples with significant copper and molybdenum from the J-Rock showing and the Sleet zone.

The HIT claims were optioned to Rackla Metals in the fall of 2022.

Further southwest, at what is now known as the SER claims, the first documented work was in 1980 by Kelvin Energy Ltd. Kelvin Energy carried out prospecting, soil sampling, geological mapping and hand trenching that year, but did not follow-up on that work and later allowed the claims to lapse.

In 1982, AGIP Canada Ltd. re-staked the property and in 1983 and 1989 they did geological mapping, prospecting and soil sampling. Following a brief visit to the property in 1990 the claims were allowed to lapse.

The property was re-staked as the Wall claims in 1996 by Kennecott Canada Exploration Inc. and in 1998 they carried out soil sampling, prospecting and geological mapping. The claims were later allowed to lapse.

In 2011, Golden Predator Canada Corp. conducted a regional exploration program of stream sediment sampling and prospecting and staked the SER, Serb, Serc and Serax claims. The company did not follow-up this work, but the claims were held in good standing until they were optioned to Rackla Metals in the fall of 2022.

Geological Setting

The Astro Plutonic Complex lies within the eastern Selwyn Basin and western Misty Creek Embayment. The Selwyn Basin is a deep‐water sedimentary basin with thick shale sequences to the southwest and an extensive carbonate platform (the Mackenzie Platform) to the east. The Misty Creek Embayment is a smaller, deep water, sub-basin of the Selwyn Basin and contains shale-carbonate transition facies with silty shale, siltstone and abundant dolostone units around its margins.

The sedimentary rocks of the Selwyn Basin and Misty Creek Embayment were intruded by biotite monzogranite of the Tungsten Suite (Canol Trail Stock, 95.0 to 99.0 Ma) followed by biotite granite of the Mayo Suite (Keele Pluton, 98.0 to 93.0 Ma), and lastly by quartz monzonite of the Tombstone Suite (Border Pluton and Kelvin Stock, 90.0 to 94.0 Ma). Small dykes and apophysis of these intrusion can be seen for many hundreds of meters around these intrusions.

The sedimentary rocks around the margins of the intrusion have been altered through contact metasomatism to form altered and mineralized contact aureoles that can be up to 1 km outboard from the intrusion. The contact aureole often contains abundant pyrrhotite and pyrite, variable copper and tungsten and can be anomalously gold-bearing.

Tombstone Gold Belt deposits and occurrences are preferentially associated with the plutonic suites that form an 800-km-long belt of several hundred relatively small stocks, dykes and sills (Hart, 2006).

Exploration Target

Rackla has identified significant RIRGS features in the Astro Plutonic Complex, including:

Stream sediment sampling on the streams draining each of the intrusions have returned anomalous gold geochemistry with coincident bismuth, arsenic, and antimony anomalies.
Airborne geophysical surveying has defined a magnetic low centered on the Canol Trail Stock, Kelvin Stock and Border Pluton each with magnetic high “shoulders” around the intrusion defining the hornfelsed contact aureole.
Soil and talus fine sampling has returned a number of coincident Au-Bi-As anomalies with several values >0.5 ppm gold.
Prospecting and geological mapping has identified an abundance of sheeted quartz-sulphide veins in each of the intrusions, particularly in the area of the HIT discovery where it reaches up to 55 veins per metre.
Rock sampling has returned several samples with gold values above 0.5 g/t gold and up to 26.5 g/t gold.

At Astro East, seven mineralized showings have been identified: Radio, Gamma, Infrared, Microwave, Ultraviolet, Lake Valley and Photon. The Lake Valley, Radio, Ultraviolet and Gamma showings have been tested with drilling.

At Astro West, 10 mineralized showings have been identified: Mehitabel (HIT), McDame, Gully, J-Rock, Ridge, Babe Ruth, Sleet, Peak, Cirque and Tour. The HIT, Gully and Ridge showings have been tested with drilling.

The most promising targets are the HIT and Peak.

HIT

At HIT, drilling in 2023 returned 0.668 g/t gold over 16.5 m and 0.607 g/t gold over 13.5 m in hole HIT-003 and 0.516 g/ gold over 45.5 m in hole HIT-004. These holes are at the northeastern end a 1.5 square km coincident gold-bismuth-arsenic soil geochemical anomaly that overlies a corridor of intense sheeted quartz-sulphide veins.

Peak

At Peak, 20% of rock samples (49 out of 237 samples) returned greater than 1.0 g/t gold with the highest value being 17.8 g/t gold. The gold occurs primarily in sheeted quartz-arsenopyrite-bismuth veins that occur in the sedimentary rocks along the eastern margin of the Kelvin Stock. The veins trend north-northeasterly and individual veins can be traced for hundreds of meters. The vein system has been traced for 1 km along strike and 1.5 km across strike. This target has not been drilled. A maiden diamond drill program is planned for 2024.