Preliminary Map 47 describes the geology and mineral occurrences of the Merritt area (92I/2f, 2g and 2h) in south central British Columbia. The two geology maps are at 1:25 000 scale and depict outcrops and mineral occurrence locations.
The oldest rocks exposed are mainly volcanic units of the Late Triassic Nicola Group. Components of the Nicola rocks are distinguished in some detail and are further separated into Central Belt, probably Central Belt and Western Belt assemblages. Central Belt rocks comprise 7 units. They are dominated by andesite to basalt flows that are typically augite phyric but include areas of laharic breccias, tuffs, limestone pods, greywacke, sandstone and siltstone. Extensive areas of epidote and potassic alteration are shown. Probable Central Belt rocks comprise 10 units. The assemblage is like that of the Central Belt but also includes a series of rhyolite flows, and felsic tuffs and fragmental volcanic rocks.
The Western Belt rocks comprise 16 units. Andesite with either plagioclase or augite phenocrysts form flows and breccias predominate but dacite flows and felsic breccias, ash flow tuffs, limestone, volcanic sandstone and siltstone, argillite and rhyolite units occur. Unconformably above the Nicola strata are Jurassic to perhaps Lower Cretaceous chert pebble to cobble conglomerate and Jurassic or Lower Cretaceous conglomerate, sandstone, siltstone and shale.
Cretaceous rocks include plagioclase and augite-plagioclase phyric flows and epiclastic rocks of the Kingsvale Group, and sandstone, arkose and shale of the Lower Cretaceous to perhaps Tertiary ‘Coldwater Beds’. The ‘Coldwater Beds’ are locally coal bearing. Rhyolite, andesite, basalt flows and fragmental volcanics are probably of Eocene age, and valley basalts were dated at about 500 000 years.
Intrusive rocks in the area include Triassic diorite, microdiorite and porphyry dikes, the Late Triassic Guichon Creek batholith, which varies from quartz diorite to granodiorite, and the Lower Jurassic or younger Pennask batholith, which is mainly granodiorite. All cut the Nicola Group rocks.
The area has potential for gold-copper vein, volcanogenic massive sulphide, copper-iron skarn and both alkalic and calc-alkalic porphyry copper deposits.