The Peter’s Gulch occurrence is located at an elevation of approximately 1720 metres on southeast-facing slope, approximately 5.8 kilometres north of the north end of Black Lake.
The area lies within the Omineca-Cassiar Mountains at the southern end of the Toodoggone gold camp. It occurs 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 Toodoggone Formation volcanic rocks of the upper volcanic cycle. These consist of a heterogeneous mixture of green, grey and mauve lapilli ash and lesser block tuff, with lesser interspersed ash flows, lava flows and interbedded epiclastics of the Attycelley member and partly welded, crystal-rich dacitic ash flows of the conformably overlying Saunders member.
Locally, Toodoggone volcanics host quartz veins with pyrite associated with a northwest-trending fault zone that has been traced for several hundred metres. The main quartz vein is approximately 1 metre wide with another metre of pyritic fault gouge and has been traced for at least 6 metres by trenching. The structure is steeply dipping and strikes 145 to 160 degrees. A second parallel, 0.2-metre wide, quartz-pyrite vein is reported approximately 30 metres below the main vein. Strike extensions of the veins have been traced for approximately 500 metres. Porphyry flows in the area are also reported to host disseminated magnetite.
A small area of high-grade copper (bornite-chalcocite-covellite) mineralization associated with calcite-epidote veining is reported to be located stratigraphically above the main vein at an elevation of approximately 1820 metres and 200 metres to the northwest of the main vein.
Another zone of mineralization is reported to be located on a ridge approximately 1 kilometre to the southeast and to comprise a small syenite plug hosting disseminated chalcopyrite and pyrite. Barite is also reported in this general area.
In 1989, three grab samples (CT-25, CT-26 and PD-58) from the main vein yielded from 1.16 to 2.70 grams per tonne gold, whereas two chip samples (FR-104 and -105) from the main vein yielded 0.99 and 1.21 grams per tonne gold over 1 metre, respectively (Property File - Delancy, P.R. [1989-10-01]: Final report on the 1989 exploration program Chappelle Property). Three grab samples (PD-60, FR-112 and PD-219) from the lower vein yielded from 3.65 to 6.78 grams per tonne gold, 46.6 to 51.7 grams per tonne silver and 0.143 to 0.215 per cent copper, whereas samples (PD-134 through -141, PD-207 through -212, PD-215 through -218 and PD-248 and -249) taken along approximately 500-metre, northeast-southwest–trending, strike extensions of the veins yielded from 0.05 to 1.20 grams per tonne gold (Property File - Delancy, P.R. [1989-10-01]: Final report on the 1989 exploration program Chappelle Property).
Also at this time, a sample (PD-214) from the high-grade copper zone yielded 11.71 per cent copper and 454.1 grams per tonne silver, whereas samples (PD-234 through -239) containing barite, taken from the ridge to the southeast, yielded values of up to 0.10 gram per tonne gold and 0.503 per cent barium (Property File –Delancy, P.R. [1989-10-01]: Final report on the 1989 exploration program Chappelle Property).
Work History
The area has been explored in conjunction with the nearby Baker/Chappelle (MINFILE 094E 026) and a complete exploration history can be found there. The occurrence is reported to have been first identified 1989.
