The geology of southwest Yukon records a complex history of terrane accretion, with the progressive addition of oceanic island arcs to the western margin of proto-North America (Laurentia) from the early Triassic to Cretaceous. Recent mapping in the Haines Junction area by the Yukon Geological Survey and Yukon College identified a previously uncharacterized package of Triassic metabasalts and metasediments. This project aims to use the whole rock geochemistry of metabasalts within this package (the Bear Creek assemblage) to identify the tectonic setting in which these rocks formed, and their relationship to other geologic terranes in northwestern Canada and Alaska.
The findings from this study have important implications for understanding the metallogenic framework in southwest Yukon, as similar Triassic volcanics in southeastern Alaska host major volcanogenic massive sulfide (VMS) deposits (e.g. Green’s Creek, Windy Craggy). The regional correlations arising from the geochemical characterization inform the location of the fundamental suture between the Intermontane terranes (e.g. Stikinia, Yukon-Tanana) and the outboard Insular terranes (Wrangellia, Alexander).
In addition to whole rock geochemistry, this study aims to characterize the regional metamorphic conditions affecting the area during orogenic thickening in the Cretaceous, using a combination of thermodynamic modelling and electron microprobe analysis.
Dr. Steve Israel (Yukon Geological Survey)
Philippe LeBlond (2015 graduate, Yukon College)
Yukon College Faculty Research Fund
Fieldwork funding provided by the Yukon Geological Survey