The petrogenesis of late Pleistocene Barambah basalts from southeast Queensland, Australia

Abstract

Magmatic activity frequently accompanies continental rifting, and is generally considered to be the consequence of adiabatic decompression melting of the convecting mantle as it upwells beneath the thinned lithosphere (McKenzie and Bickle, 1988). The volume and composition of the magmas generated during rifting have been shown to be directly related to the degree and duration of extension, the temperature of the underlying asthenospheric mantle. Extension and thinning of the lithosphere cause adiabatic decompression melting of the asthenospheric mantle. Additionally, melting within the lithospheric mantle may occur through direct partial melting of metasomatised layers, resulting in magmas that are enriched in incompatible trace elements (McKenzie, 1989). Small-volume mafic alkaline volcanism occurs in many geologically recent areas of continental extension. The geochemistry of primitive volcanic rocks can be used to model partial melting conditions and assess relative contributions of lithospheric and asthenospheric mantle melts. ... This study focuses on the chemical and isotopic study of the late Pleistocene Barambah basalts from southeast Queensland, to evaluate their mantle source characteristics and evolution.