The Northwest Marmot occurrence is located at an elevation of approximately 1700 metres on the east side of a ridge separating Caribou Creek to the east and Cloud (Silver) Creek to the west, approximately 9.9 kilometres southeast of the junction of Lawyers Creek and the Toodoggone River.
The area lies within the Omineca-Cassiar Mountains at the southern end of the Toodoggone gold camp. The area is situated within a Mesozoic volcanic arc assemblage that lies along the eastern margin of the Intermontane Belt, a northwest-trending belt of Paleozoic to Neogene sediments, volcanics and intrusions bounded to the east by the Omineca Belt and to the west and southwest by the Sustut and Bowser basins.
Permian Asitka Group crystalline limestones are the oldest rocks exposed in the region. They are commonly in thrust contact with Upper Triassic Takla Group andesite flows and pyroclastic rocks. Takla volcanics have been intruded by Lower Jurassic granodiorite to quartz monzonite of the Black Lake Suite and are in turn unconformably overlain by or faulted against Lower Jurassic calc-alkaline volcanics of the Toodoggone Formation (Hazelton Group).
The dominant structures in the area are steeply dipping faults that define a prominent regional northwest structural fabric trending 140 to 170 degrees. In turn, high-angle, northeast-striking faults (approximately 060 degrees) appear to truncate and displace northwest-striking faults. Collectively these faults form a boundary for variably rotated and tilted blocks underlain by monoclinal strata.
The occurrence area is underlain by andesite crystal tuffs, volcaniclastic breccias and hypabyssal quartz trachyandesites, part of a larger package of Toodoggone Formation volcanics assigned to the Metsantan member and dacitic volcanic rocks of the Saunders member. Other lithologies of the Metsantan member include mostly latite lava flows with interflow lahar, and a mix of epiclastic and pyroclastic rocks (Bulletin 86).
Locally, the style of mineralization is not described but is likely similar to that of other nearby occurrences and comprises epithermal style quartz veining and/or breccia with associated gold and silver values.
In 1971, a sample grey tuff with pyrite, located approximately 300 metres to the northwest, yielded 17.6 grams per tonne silver (Assessment Report 3416).
In 2018, a rock sample (Y445280) from outcrop assayed 8.22 grams per tonne gold and 897 grams per tonne silver, whereas two nearby rock samples (Y445281 and Y445282), taken to the southeast of the previous sample, yielded 0.420 and 0.310 gram per tonne gold with 60.1 and 55.0 grams per tonne silver, respectively (Assessment Report 38447). No sample descriptions were provided for the previous samples.
Samples from north-northeast–trending structures hosing fine-grained sulphide mineralization, referred to as the LaLa zone, yielded values of up to 8.22 grams per tonne gold and 897.0 grams per tonne silver (P&E Mining Consultants Inc. [2021-06-28]: Technical Report and Updated Mineral Resource Estimate of the Lawyers Gold-Silver Property, Omineca Mining Division, British Columbia, Canada).
Work History
The area has been historically explored in conjunction with the nearby Lawyers (MINFILE 094E 066) and Silver Cup West (MINFILE 094E 163) occurrences and a complete exploration history can be found there.
During 1971 through 1973, Kennco Explorations completed programs of geochemical (rock, silt and soil) sampling, prospecting and geological mapping on the area as part of the Lawyer property.
In 2018, Benchmark Metals Inc. and PPM completed a program of geochemical (rock and soil) and biogeochemical sampling, a 1272 line-kilometre airborne radiometric survey, eight diamond drill holes, totalling 1493.0 metres, and 30 rotary drill holes, totalling 2623.0 metres. This work focused along the Layers mineralization trend, which is greater than 3 kilometres in length.
In 2019 and 2020, Benchmark Metals Inc. completed programs of geochemical (rock and soil) and biogeochemical sampling, ground and airborne geophysical surveys, 242 diamond drill holes, totalling 69,080 metres, and 191 reverse circulation drill holes, totalling 28 395 metres, on the area as part of the Lawyers property. The majority of the drilling targeted the Cliff Creek, Dukes Ridge, Phoenix and AGB zones of the Lawyers (MINFILE 094E 066) deposit.
