Minor and trace elements in augite, hornblende, and pyrope megacrysts from Kakanui, New Zeland

Abstract

Minor and trace elements have been determined in augite, hornblende, and pyrope megacrysts by neutron activation analysis and spark-source mass spectrometry, and the results are compared with published data. The lanthanide patterns are especially significant; relative to chondritic abundances, augite shows a comparatively unfraction- ated pattern, whereas hornblende is progressively depleted and pyrope progressively enriched in the heavier lanthanides. The lava accompanying the megacrysts appears to have been derived from a basaltic magma by the removal of pyrope followed by selective crystallisation. © 1973 Taylor & Francis Group, LLC.