Geology of the Natalkuz Lake Area, Central British Columbia
BCMEMPR Open File 1993-14
Scale 1:50 000
View Open File 1993-14 (PDF, 4.9 MB)
Open File 1993-14 presents the geology of the Natalkuz Lake area (93F/6) in north central British Columbia. The 1:50 000 scale geology map includes a legend, references, and a list of mineral occurrences.
The oldest layered rocks in the area are strata of the Early to Middle Jurassic Hazelton Group. Two mappable units, variegated green and maroon ash and lapilli tuff, and feldspar and augite phyric andesite flows are described. Minor amounts of epiclastic rocks also occur. Overlying Middle to perhaps Upper Jurassic rocks of the Ashman Formation of the Skeena Group consist of argillite and siltstone, and this unit is overlain by andesite to dacite crystal, lapilli and block tuff. Lower to perhaps Upper Cretaceous rocks include pebble breccia, lithic wacke, siltstone and mudstone of the Skeena Group, andesite block to lapilli tuff, and rhyolite flows and cogenetic sills. Lower to Middle Eocene rocks of the Ootsa Lake Group comprise seven mappable units: coarse feldspar andesite flows; blue grey and pink dacite flows; rhyolite flows with associated tuff and tuffaceous sediments; andesite flows; grey rhyolite flows with up to 25% quartz phenocrysts; and rhyolitic crystal-lapilli tuff. Endako Group basalt is of Upper Eocene to Oligocene age. Miocene to Quaternary Chilcotin Group olivine basalt flows overlie the older rocks.
Intrusive rocks include the Late Cretaceous Capoose Lake batholith, which is quartz monzonite to granodiorite, and Tertiary small stocks and dikes of quartz feldspar porphyry, k-feldspar quartz porphyry, and gabbro.
The area is poorly exposed but normal faulting with northeast, north and north-northwest have been mapped.
The area includes the Capoose prospect, which is hosted within and adjacent to garnet-bearing rhyolite sills that intrude Hazelton Group volcanic and sedimentary rocks. Mineralization in this porphyry prospect is mainly disseminated but also occurs in veinlets and fracture fillings. Minerals of interest are sphalerite, galena, and chalcopyrite. Reserves are reported at 28 million tonnes grading 0.51 g/t gold and 36 g/t silver. Other occurrences in the area include vein-controlled and disseminated chalcopyrite and molybdenite in the Capoose Lake batholith.
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