| Issue ID: | P2012-01-10 |
| Title: | Structural Geology of the Alexander Terrane in the Vicinity of Porcher Island, Northwestern British Columbia |
| Author(s): | Angen, J.J., van Staal, C.R., Lin, S. |
| Series Name: | Paper |
| Publication Year: | 2012 |
| Larger Work Citation: | in Geological Fieldwork 2011, B.C. Ministry of Energy and Mines, Paper 2012-01 |
| Place Keyword(s): | British Columbia, Coastal, Porcher Island |
| Lat/Long (NSWE): | 54.1, 53.8, -130.6, -129.8 |
| Theme Keyword(s): | Geological Fieldwork, Alexander terrane, Coast Plutonic Complex, geochronology, structural geology |
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Abstract:
| This report summarizes the preliminary results of a two year study, mainly using detailed structural analysis combined with U-Pb geochronology, to elucidate the structural history of Porcher Island and the surrounding area in northwestern British Columbia. This work is a contribution to the North Coast subproject of the Edges Multiple Metals – NW Canadian Cordillera (British Columbia and Yukon) Project, the overall scope and results of which are elaborated upon by Nelson et al. (2012). The study area is situated near the eastern margin of the southern Alexander terrane. The tectonic and paleogeographic history of the Alexander terrane is complex, and differs significantly from that of terranes which developed closer to the paleo-Pacific margin of North America. Excellent coastal exposures and a polyphase structural history make this area a strategic location to study the various tectonic events recorded by the southern Alexander terrane. New U-Pb geochronology combined with structural observations within the Ogden Channel complex (Nelson et al., 2010) has led to the identification of a Late Silurian to Early Devonian tectonomagmatic event. Original interaction of the Alexander terrane with the paleo-Pacific margin of North America is interpreted as pre-Middle Jurassic. The boundary has since undergone significant contraction and extension-related deformation, with both sinistral and dextral transcurrent components. New evidence indicates that sinistral and dextral shear zones were in part coeval, forming a conjugate set. |
