The Gravy IV occurrence is located at an elevation of 1720 metres on a north-trending ridge, approximately 1.5 kilometres east-southeast of Mount Graves.
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 the early Jurassic granodiorite to quartz monzonite 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 area is underlain by volcanics and volcaniclastics of the Jurassic Hazelton Group. These rocks form the eastern limb of a north-northwest–trending faulted anticline. Regionally, these rocks have been subdivided into four informal units (Forster, 1984) that, at the Mount Graves prospect, dip 50 to 80 degrees to the northeast. Welded and partially welded andesite pumice breccia, overlain by grey, green to orange hornblende porphyritic andesitic flows and pyroxene andesite flows; lesser thin discontinuous lenses of greywacke and laminated siltstone comprise lithologies of the Hazelton Group. Quartz monzonite dikes are found in the faulted core of the regional anticline and along northeast- and east-striking faults. A series of quartz feldspar porphyry rhyolitic dikes, striking northwest and dipping steeply, occur subparallel to bedding.
Locally, the mineralization is not reported but is likely similar to that of the nearby Mount Graves (MINFILE 094E 087 and 203) occurrences and comprise quartz veining with galena, sphalerite, chalcopyrite and barite.
In 1985, a rock sample (810) assayed 0.170 gram per tonne gold, 18.1 grams per tonne silver, 0.913 per cent copper, 0.688 per cent lead, 0.323 per cent zinc and 0.011 per cent cadmium, and another sample (821) taken approximately 200 metres to the northeast yielded 2.5 grams per tonne silver, 0.116 per cent lead, 0.215 per cent zinc and 0.006 per cent cadmium (Assessment Report 14436). Soil samples from the area yielded up to 46.9 grams per tonne silver and 0.455 gram per tonne gold (Assessment Report 14436).
In 2004, a rock sample (185946) of a 0.1-metre wide chlorite-altered quartz vein with trace galena, located approximately 700 metres to the southwest, assayed 0.381 per cent zinc (Assessment Report 27734).
Work History
The area has been explored in conjunction with the nearby GWP (MINFILE 094E 087) and Gravy (MINFILE 094E 205) occurrences and a completed exploration history can be found there.