Metadata record for data from ASAC Project 56
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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. The dykes have 10 Mg/ (Mg+Fe2+) ratios and Ni and Cr abundan ces too low for primary magmas derived from commonly envisaged uppedr mantle peridotite sources [with 100 Mg/(Mg+Fe)-89]. Instead, they could represent either primary magmas derived from relatively Fe-rich mantle, or be the products of pre-emplacement fractional crystallisation of olivine and clinopyroxene from more Mg-rich parental magmas. The high incompatible-element and REE abundances of the dykes suggest that their mantle sources were either undepleted or re-enriched, and that the degree of melting was probably small. It seems likely that this alkaline magmatic activity was related to the formation of the nearby Lambert Graben.