Guest, BernardRussell, James K.Kuehn, Christian2014-10-242015-02-232014-10-242014http://hdl.handle.net/11023/1936Alkaline and peralkaline magmatism occurred along the Anahim Volcanic Belt (AVB), a 330 km long linear feature in west-central British Columbia. The belt includes three felsic shield volcanoes, the Rainbow, Ilgachuz and Itcha ranges as its most notable features, as well as regionally extensive cone fields, lava flows, dyke swarms and a pluton. Volcanic activity took place periodically from the Late Miocene to the Holocene. A systematic decrease in the ages of individual centres from the western part of the AVB to its eastern end is interpreted as the effect of a hot-spot underlying the Interior Plateau of British Columbia. Other hypotheses for the existence of the AVB include regional extension, a plate edge/slab window effect along the northern edge of the subducted Juan de Fuca/Explorer plates, and a fracture propagating west to east. In this study, I first summarise existing works to provide a context for AVB volcanism. Then I report new whole-rock geochemical data and 40Ar/39Ar age determinations for two previously little-studied cone fields around Satah Mountain and Baldface Mountain in the central part of the AVB. Individual volcanic centres in these fields are generally small in extent and volume and most have been heavily modified by glacial erosion. These centers are compositionally heterogeneous but overall the lavas erupted in either field are similar to those erupted from the larger Itcha Range shield volcano nearby. Rock types include minor alkali basalts and basanites (44−52 wt% SiO2), but more evolved trachyandesites, trachytes and phonolites (59−64 wt% SiO2) are the most abundant lithologies. Timing of volcanism in the Satah Mtn. field is constrained by 11 40Ar/39Ar ages which indicate volcanism between 2.21 and 1.43 Ma; in the Baldface Mtn. field, seven age data indicate volcanism from 2.52 to 0.91 Ma. The data further indicate that volcanic activity in these fields was, at least partially, coeval with the Itcha Range. These new data provide additional support for the mantle plume/hot-spot hypothesis, the only hypothesis that accounts for both the (per)alkaline character of AVB magmatism and the linear age-succession of volcanic centres.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.GeologyAnahim volcanic beltHot-spot volcanismVolcanism in western CanadaAlkaline volcanismCanadian Cordilleradoctoral thesis10.11575/PRISM/25002