The White Bull occurrence is situated in the centre of the White Bull claim, 14 kilometres north-northwest of the junction of the Dall and Turnagain rivers, 16 kilometres northwest of Inspector Peak in the Cassiar Mountains (Assessment Report 19830, Figure 2.2). The area was originally a target for shale-hosted lead-zinc mineralization (Assessment Reports 6839, 11190).
The occurrence lies in an area of moderately deformed Upper Proterozoic and Lower Paleozoic rocks of the Cassiar terrane, between the Northern Rocky Mountain Trench and Kechika dextral strike-slip faults (Geological Survey of Canada Maps 42-1962, 1712A, 1713A). Units include the Ingenika, Atan, Kechika, Road River and Sandpile groups. The White Bull claim is underlain mainly by the Cambro-Ordovician Kechika Group, and possibly some of the Road River Group locally, and a felsic intrusion of probable Cretaceous age (Assessment Report 19830). The property is on the southwest limb of a gently northwest-plunging anticline, the hinge zone of which is approximately 7 kilometres to the northeast. Bedding strikes northwest and dips moderately southwest. The rocks are cut by a few north-northwest–striking faults, which dip moderately west to subvertically.
The Kechika Group here comprises a variety of rocks including phyllitic limestone, tuffaceous phyllite or schist, dark grey to black dolostone and graphitic to calcareous phyllite, bedded dolostone, sandy dolostone, argillite, chert and sericite schist. Interbedding of some of the units may be primary or may be the product of tight folding. The potassic, felsic intrusion is pale brown, fine-grained and forms rusty weathering outcrops in the north of the property. It has quartz phenocrysts and may be of rhyodacite composition. It has pervasive silica and potassium feldspar alteration. Dating this material by the potassium-argon method yielded a mid-Cretaceous age of 113 ± 4 million years for this hydrothermal event (Assessment Report 19830).
Exploration in the area was aimed at areas of surface alteration and vegetation 'kill zones', marked by ferricrete and sulphate-rich bleached zones up to 15 metres thick (Assessment Reports 11190, 19830). These areas are developed discontinuously in the centre of the property for approximately 1800 metres in length and up to 300 metres in width. They consist of limonite, jarrosite and other iron sulphates, gypsum and locally native sulphur (Assessment Report 19830). Unmineralized argillite and sericitic schist generally lie beneath the alteration caps. Elsewhere, quartz-sericite hydrothermal alteration with up to 3 per cent pyrite may be developed in dolostone, tuffaceous volcanics and argillite. A green mineral, possibly mariposite or fuchsite, was found in a few places.
All the units are cut by unmineralized, massive white quartz and calcite veins. Coarse white barite veins and siderite veins are less common.
Apart from the fine- to medium-grained, disseminated to massive pyrite and quartz-calcite-pyrite veins generally associated with the quartz-sericite alteration mentioned above, base metal mineralization on the White Bull property is restricted to very local and minor sphalerite (Assessment Report 19830).
In 1996, samples from a poorly exposed 0.5-metre wide and 50-metre-long chert/barite bed, trending east-west with a near-vertical dip, yielded values up to 56.76 per cent barium (sample PK-4), whereas a channel sample (PK-34) from the east end of the horizon assayed 0.88 per cent lead and 6.3 grams per tonne silver over 2.0 metres (Assessment Report 24454). Also at this time, two samples (PK-106 and PK-107) of iron-rich carbonate(?) pods, up to 0.3 metre in diameter, hosted near the contact of phyllite-argillite with underlying dolomite and located approximately 200 metres south-southeast of the previous samples, assayed 0.07 and 0.03 per cent lead, 4.1 and 4.2 grams per tonne silver with 0.96 and 0.76 gram per tonne gold, respectively (Assessment Report 24454).
Work History
In 1978, Amoco Canada Petroleum Company Ltd. completed a soil sampling program on the area as the Wendy claims. In 1982, Esso Resources Canada Ltd. completed a program of soil sampling and ground magnetic and electromagnetic surveys on the area as the Red Bull, Tan Bull and White Bull claims of the White property. In 1989, Homestake Mining (Canada) Ltd. completed a program of geological mapping and geochemical (rock and soil) sampling on the White Bull claim.
In 1995, with Explore B.C. support, Atna Resources Ltd. carried out a program of regional reconnaissance prospecting including geological mapping, soil and rock geochemistry. This program located three areas of significant mineralization and at least one exhalative sedimentary horizon on the west part of the White Bull grid. Most sulphides in this unit are leached away, indicating the need for drilling (Explore B.C. Program 95/96 - G50).
In 1996, Atna Resources Ltd. completed programs of geological mapping and rock sampling on the White Bull 1-2 claims. In 2004, Atna Resources completed a further program rock sampling on the claims.
In 2012, Rara Terra Capital Corp. completed a 696.4 line-kilometre airborne radiometric survey on the area immediately east as the Xeno claims.
