Metamorphic and Structural Evolution of the Precambrian Basement in the Northern Prince Charles Mountains

From the abstract of the referenced paper: Thin mafic dykes emplaced in ca. 100 Ma granulite-facies basement and Permian Amery Group strata around Radok Lake, Northern Prince Charles Mountains, are high K/Na alkaline andesites or basalts. They include three petrographic groups, namely (1) plagioclase plus or minus olivine-phyric, (2) clinopyroxene plus or minus olivine-phyric and (3) aphyric dykes.

Clionpyrozene and phenocrysts in group (2) dykes comprise low-P phenocrysts, xenocrysts of possible mantle derivation, and probably high-P cognate phenocrysts. Incompatible element rations separate the dykes into three or four groups (broadly though not exactly coinciding with the petrographic subdivision) probably representing separate magmas derived either from chemically dissimilar mantle sources, or by different degrees of melting of a source in which one or more phases rich in incompatible elements (eg phlogopite) persisted in the residua.