Stop 25 HAZ Geotour 2020

Location ID: Stop25_Haz_GeoTour2020

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The road cuts here are porphyritic andesites, lahars and thin bedded tuffaceous volcanic sediments of the Upper Cretaceous Kasalka Group. There is a well defined, northeast dipping contact between a 10-metre-thick interval of dark grey, well bedded tuffaceous rocks and overlying light grey porphyry flows exposed on the west side of the road. At the base of the porphyry is a thin red tuff horizon. The porphyry, which is comprised of 25-30%, equant, 5-8-millimetre feldspar phenocrysts in a finer grained groundmass is typical of the Kasalka Group as defined in the type area near Tahtsa Lake (MacIntyre, 1985). The same rocks are found at higher elevations in the Babine Range.

At approximately 15.4 kilometers from Moricetown there are a series of rusty cream coloured outcrops of argillic altered volcanics (Kasalka?) containing disseminated pyrite exposed in the road cuts. The alteration and sulphide mineralization here is peripheral to a porphyry stock that underlies the area east of the river. The altered rocks have elevated concentrations of Pb and Zn. Drilling of the porphyry stock failed to intersect significant copper or molybdenum grades. The alteration displayed by the rocks along the road is interpreted to be high level and is like that found associated with subvolcanic intrusions at Buck Creek in the Houston area and Coles Creek, south of Tahtsa Lake.


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Location Data

Longitude: -127.3822
Latitude: 55.1065