The Signature of Amphibole in Mafic Alkaline Lavas, a Study in the Northern

Despite evidence for its involvement, the importance of amphi-bole in controlling the compositions of mafic alkaline magmas remains under-appreciated. Relatively small variations in large ion lithophile elements (LILE) with respect to other incompa-tible elements, such as light rare-earth elements (LREE) or Th, require that amphibole was an important residual phase during the production of Late Tertiary to Recent olivine neph-elinite (Ol-NEPH) magmas beneath the northern Canadian Cordillera. The erupted mafic magma types define a continuous array from Ol-NEPH to hypersthene-normative olivine basalt (Hy-NORM AOB). The overall compositional array has a sense of curvature which is counter to binary mixing, but can be modeled by two distinct linear melting trends: one from Ol-NEPH to basanite (BASAN) compositions, during which amphibole controlled the composition of the melt, and the ratio