A preliminary investigation of the igneous origins of the Montney and Doig formations: Integrating igneous geochemistry techniques for interpreting sedimentary provenance

Abstract It is well documented through sedimentological and zircon provenance studies that the bulk of the Montney sediment is sourced from the eastern North American Craton (NAC), consisting of highly felsic and heavily fractionated crustal rocks. This study presents the application of immobile element ratio diagrams to understand igneous and tectonic source terrains of the NAC sediments that source the Montney and Doig formations. Igneous rock plots, and tectonic discriminant diagrams, display Montney and Doig samples as rhyodacite-dacite with syn-collisional granitoid and volcanic arc signatures. Aluminum oxide and Mid-Ocean Ridge Basalt (MORB) normalized plots, which contain an array of elements including rare earth elements (REE) along with major oxides, show the Montney and Doig formations to have similar trends to calc-alkaline basalts, meaning highly felsic with a likelihood of crustal contamination. The Montney and Doig formation samples all show similar geochemical trends; however differences in Y and Yb trends suggest the Doig source samples were exposed to greater degrees of potential garnet, clinopyroxene or biotite fractionation, this trend displays more mafic-ultramafic influences. These mafic-ultramafic trends were not exhibited in the Montney Formation samples.