Southern Nicola Arc Project (SNAP): Preliminary results Mitchell G. Mihalynuk1, a, James M. Logan1, Larry J. Diakow1, Richard M. Friedman2, and Janet Gabites2 1 British Columbia Geological Survey, Ministry of Energy and Mines, Victoria, BC, V8W 9N3 2 Pacifi c Centre for Isotopic and Geochemical Research, Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4 a corresponding author:
[email protected] Recommended citation: Mihalynuk, M.G., Logan, J.M., Diakow, L.J., Friedman, R.M., and Gabites, J., 2014. Southern Nicola Arc Project (SNAP): Preliminary results. In: Geological Fieldwork 2013, British Columbia Ministry of Energy and Mines, British Columbia Geological Survey Paper 2014-1, pp. 29-57. Abstract Geological fi eld studies in 2013 took advantage of new access and exposures from extensive clear-cut timber harvesting between Princeton and Tulameen. Revision mapping and laboratory investigation reveal new facets of the prolifi cally mineralized Nicola arc. 40Ar/39Ar cooling and U-Pb crystallization ages show that volcanism, long considered restricted to the Late Triassic, extends into the Early Jurassic. Volcanism changes near the Triassic-Jurassic boundary from feldspar-pyroxene ± olivine-phyric, to hornblende as an accessory or even principal phenocryst phase, perhaps indicating a change to more hydrated magma sources. Felsic volcanic rocks interpreted as part of the Nicola arc occur north of Princeton and near Tulameen, where a bimodal submarine succession contains previously unreported, possible exhalite horizons with copper mineralization. A northerly trending high-strain zone can be traced intermittently for ~ 20 km. It bisects the study area, with strain focused in calcareous strata.