Petrochemistry of the Auckland basalts

Abstract

Thirteen new analyses of lavas from Auckland are presented and discussed. The rocks are shown to be olivine-rich alkaline basalts, chemically comparable with lavas from the Pacific basin but possibly derived by crystallisation fractionation along a trend characteristic of a continental environment. The composition of the Auckland rocks is compared with that of Pliocene-Pleistocene basalts from Northland and from South Auckland. The origin of olivine nodules and a nepheline basanite associated with the Auckland basalts is considered. © Taylor & Francis Group, LLC.