Publication Summary
Issue ID: P2013-01-09
Title: Geology, U-Pb Geochronology, and Geochemistry of the Miocene Phenol Mountain Complex, Hoodoo Mountain Area, British Columbia
Author(s): Zagorevski, A., Dziawa, C., Friedman, R.M., Mihalynuk, M.G.
Series Name: Paper
Publication Year: 2013
Larger Work Citation: in Geological Fieldwork 2012, B.C. Ministry of Energy, Mines and Natural Gas, Paper 2013-01
NTS Map Sheet(s): 104B/14
Place Keyword(s): British Columbia, northwest, Hoodoo Mountain, Pheno Mountain
Lat/Long (NSWE): 57, 56.75, -131.5, -131.25
Theme Keyword(s): Geological Fieldwork, Northern Cordilleran Volcanic Province, silica-saturated, felsic magmatism, alkaline rhyolite
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Abstract:
The Pheno Mountain complex comprises rhyolite, trachyte and intrusive quartz feldspar porphyry that form extrusive and hypabyssal portions of a volcanic complex. A subvolcanic quartz feldspar porphyry with columnar jointing and brecciated margins underlies petrographically identical volcanic rocks. It yielded a 7.78 0.01 Ma U-Pb zircon crystallization age, which is interpreted to constrain the age of the Pheno Mountain complex. Both the volcanic and hypabyssal rocks are characterized by high Nb/Y, Nb, Y, and Zr suggesting that they formed in a within-plate setting by fractional crystallization from an alkali basalt parent. These data support correlation of the Pheno Mountain complex with the Neogene to Quaternary Northern Cordilleran Volcanic Province. However, in contrast to the coeval Mount Edziza and Level Mountain volcanic centres, magmatism in the Pheno Mountain complex does not appear to be preceded by construction of a basaltic shield.