The Castle East area is underlain by of the Lower Jurassic Hazelton Group (Unit Javb, Open File 1997-03) consisting of andesitic volcanic breccias and conglomerates. The Hazelton rocks unconformably overlie or are in fault contact with Stuhini Group sedimentary rocks to the south.
Reconnaissance mapping of the Castle East by West Cirque in 2013 outlined an outcropping zone of altered monzodiorite to monzonite porphyry at least 600 meters in strike length near the valley bottom. Many of the porphyry outcrops have undergone intense quartz-sericite-pyrite (QSP) alteration which represents the eastern extension of the phyllic zone on the west side of the ridge. Sample M458623 graded 1.24 grams per tonne gold, 1.2 gramss per tonne silver, and 0.039 per cent copper (green chlorite-sericite-pyrite-calcite altered monzonite, calcite veinlets, pyrite-chalcopyrite stringers and as disseminations) (Assessment Report 34551).
At the Castle East, a grab of a 12-centimeter-wide quartz carbonate vein with chalcopyrite assayed 2.8 grams per tonne gold, 44.2 grams per tonne silver and 6.9 per cent copper (Assessment Report 25432).
The Castle Alteration Zone (CAZ) of the Castle property closely tracks the east-west strike orientation of a weakly arcuate shaped, highly elongate monzodiorite. The central intrusive core of the CAZ is formed from an intrusive body which ranges in width from approximately 200 to 500 metres. This intrusion has a known strike length of approximately 5 – 6 kilometres. It is terminated to the east only by the eastern property boundary of the Castle property and to the west by a much younger Neogene volcanic cover. These intrusions have macroscale characteristics similar to other monzonites and monzodiorites in this district which range in age from approximately 205 to 215 Ma. Recent Re-Os dates by van Straaten (2017) date the main monzodiorite intrusions at Castle as 206.1 +/- 0.9 Ma, within that time fram of an important porphyry copper – gold event in the Iskut area.
Chalcopyrite is the main copper bearing mineral in the Castle porphyry. Near surface malachite and azurite are also common. Throughout the property, even in weakly altered rock, chalcopyrite is present in calcite+hematite veins. Within the main alteration zones of the Castle stock mineralization is mainly present in stockwork veins and hydrothermal breccias; the style of mineralization is dependent on the type of alteration present and the two main alteration/mineralization facies are described below. Gold concentrations increase with increased amounts of pyrite and chalcopyrite. Molybdenite is present in low concentrations, often in association with quartz-stockwork where it is barren of copper mineralization.
Recent geological mapping by Colorado Resources (2017) suggested that rock alteration is associated with enhanced gold and copper geochemistry, with multiple intrusive phases and brittle deformation zones. The Castle Alteration Zone (CAZ) forms a slightly arcuate shaped east-west-trending corridor which has a strike length of approximately five kilometres. The CAZ continues to the eastern property boundary and is overlain to the west by younger volcanic cover. Within the CAZ, rock alteration is characterized by both enhanced QSP (quartz-serricite-pyrite) and locally potassic alteration. Mineralization has affinities to both porphyry gold-copper systems and intermediate sulphidation structurally controlled gold-silver veins. Potassic altered host stockwork quartz and/or magnetite veins often contain fine to coarse disseminated or lens/band shaped occurrence of chalcopyrite. Phyllic altered rocks often have high concentrations of gold associated with both increased chalcopyrite and pyrite proportions.
Merged data from the 2017 program of Colorado Resources along with historic soil samples (1,242 soil samples) are illustrated in figures 2 and 3 available on-line as part of the Colorado Resources, January 5, 2018 News Release (www.coloradoresources.com/projects/bc-properties/kinaskan-castle-property/maps-sections/). Figure 2 shows how anomalous gold-in-soil geochemical data closely track the Castle Alteration Zone (CAZ). Gold geochemistry over 200 parts per billion (ppb) gold in soils forms a series of well-defined segments, from a few hundred metres to over 600 metres in strike length within the broader CAZ. The over 200 parts per billion gold contour is superimposed on a broader 100 parts per billion gold-in-soil anomaly.
Strongly elevated copper geochemical data, defined by the over 300 part per million-copper contour, track portions of the CAZ over its five kilometre strike length. One of the largest such area occurs from the Castle East MINFILE showing (104G 253) southward towards (but not including) the A9 MINFILE showing (104G 162). This Castle East copper-in-soil anomaly is in part coincident with the over 200 parts per billion gold-in-soil anomaly. Several grab samples from the area were high in copper and gold; sample 136522 taken near the Castle East showing yielded 84.0 grams per tonne gold and 7.42 per cent copper (Colorado Resources, January 5, 2018 News Release). Other significant samples occur north of the A9 showing.
In 2018 Colorado completed additional IP lines to the east of Castle, defining a chargeability anomaly over Castle East, with associated copper, gold and porphyry pathfinder elements.
Work History
The Castle #l and Castle #2 claims, totalling 27 units, were staked by Teck in 1980 as part of a regional program. After limited soil sampling and mapping it was found that geochemical anomalies in gold, silver and copper were associated with a large, heavily pyritized zone in volcanic rocks. The Castle #1 was allowed to lapse. In 1985, hand trenching, chip sampling, magnetometer, self potential and VLF surveying yielded positive results with Au values up to 8.2 grams per tonne gold over 3 metres. The CAS 1 to CAS 4 claims were added in 1987. The A9 area is encompassed by the Cas 2 claim as are the Castle East and Castle Central Zone. The Castle zone (104G 076) or the Main zone occur to the west on Castle #2 claim
In 1989, Ascot Resources Ltd. carried out a detailed silt geochemical sampling program over the entire Klastline Plateau that resulted in the staking of the 20 unit TUK claim to cover an anomalous drainage and colour anomaly about 2500 meters east of the Castle showing. In 1990 and again in 1991, Ascot carried out small prospecting and geological mapping programs along with silt and contour soil sampling which in part covered the northeast comer of the TUK 1 claim before allowing the claims to lapse.
In 1997, work by Teck Corporation consisted of 1:10,000 scale mapping of the property and mapping with concurrent rock sampling on the poorly explored and previously, largely unsampled Castle East Zone, which hosts the widest extent of alteration on the property, and the Castle Central (Assessment Report 25432). The higher gold values were obtained from quartz-carbonate-chalcopyrite veins, quartz- pyrite veins and in silicified zones, commonly associated with the pyrite-sericite-quartz bearing structures. The maximum values obtained were only 1.5 grams per tonne Au over 3.0 metres, 2.34 grams per tonne Au over 1.5 metres (Assessment Report 25432).
In 2002, Viceroy Resource Corporation staked the TUK 1 claim immediately east of a claim covering the Castle Mineral showing (Castle Main) and trend. The TUK 1 covers the southwestern portion of the old TUK claim and the northern half of Teck's Cas 1 claim.
In February of 2017, a 100 per cent interest in the Castle portion (163.72 square kilometres) of the larger Kinaskan (163.72 square kilometres) claim block was acquired by Colorado Resources Ltd from Kaizen Discovery Inc. Later in 2017, Colorado Resources Ltd conducted work on its Kinaskan-Castle (K-C) property. Work was focused on the four-kilometre-long central and eastern end of the Castle alteration zone (CAZ). Colorado collected soil and rock samples, geologically mapped a 10 square kilometre area and completed 11-line kilometres of IP and 150-line kilometres of airborne magnetics in September before weather caused an early shut down of the program. During the 2017 field program, 856 reconnaissance soil samples were collected on 200-metre line spacings with 50 metre centres on north-south-orientated lines south and east of the Castle MINFILE occurrence (104G 076). Prospecting covered much of the five-kilometre strike of the Castle alteration zone (CAZ) and resulted in the collection of 191 rock samples (73 chips, 15 composites and 103 grabs). Several rock samples were taken in the Castle East vicinity and produced values in gold ranging from 2.1 grams per tonne to 123 grams per tonne gold. About 19 rock samples taken about 400 metres southwest of Castle East were only slightly elevated in gold with the highest being 0.03 gram per tonne gold (Assessment Report 37464). An airborne magnetic survey was also carried out covering some 150-line kilometres of the Castle property, covering the Castle, Castle Central, Castle East and Tuk areas. The A9 showing was about 200 metres to the southeast of the survey.
In 2018, Colorado extended induced polarization survey coverage on the property that produced chargeability anomalies coincident with large gold and copper soil geochemical anomalies, which extend along an east-west trend for more than 2000 metres. The anomalies are interpreted to be sourced from underlying early Jurassic monzodiorite porphyry intrusive (+/-volcanic) rocks, potentially similar in age and lithology to those described as the same rock units that host the Saddle North and Saddle South discoveries on the Tatogga property to the immediate east (see 104G 432 and 433).
In 2019, porphyry-style mineralization was discovered at Castle East. Late in 2019 Colorado Resources completed 1555 metres of drilling at the East Castle zone (104G 253 and 254) targeting coincident gold and copper anomalies (detected from sampling) and chargeability anomalies.
Three of the drill holes, CAE 19-01, CAE 19-02 and CAE 19-03, are located from 200 to 400 metres east of the Castle East MINFILE plot with the fourth, CAE 19-04, located about 50 metres northwest of the Castle Central MINFILE plot.
Three of four holes intersected broad copper-gold-molybdenum values in what is thought to be the pyritic outer shell of a porphyry system, for example: DDH CAE19-01 intersected 14.9 metres grading 0.10 per cent copper and 0.52 grams per tonne gold. DDH CAE19-02 intersected 248.2 metres grading 0.07 per cent copper, including 22.8 metres grading 0.15 per cent copper and 0.0053 per cent molybdenum (Colorado Resources Ltd, News Release, December 9, 2019)
See Castle (104G 076) for further geological details and pertinent work history.
