The Newer Volcanics Province of southeastern Australia: a new classification scheme and distribution map for eruption centres

Abstract

A new volcanic distribution map of the 4.5 Ma–5000 B.P. continental intraplate Newer Volcanics Province in southeastern Australia has been produced in order to document >704 eruption points from >416 volcanic centres. Volcanic centres were classified as either simple or complex, with simple centres featuring few eruption points and simple morphologies, while complex centres have multiple eruption points and complex morphologies. Centres were further characterised according to the nature of their deposits. Simple volcanoes take the form of lava shields, scoria cones, maars, ash cones and domes, and unknown eruption types. Complex centres may feature exclusively magmatic eruption products such as lava and scoria, and are therefore classified as magmatic volcanic complexes; maar volcanic complexes feature exclusively phreatomagmatic eruption products and have erupted under the influence of external water, while maar–cone volcanic complexes feature both magmatic and phreatomagmatic eruption products. Approximately half of the eruption points in the Newer Volcanics Province are associated with complex volcanic centres. The minimum area of the Newer Volcanic Province was calculated to be >19 000 km², which may be a great underestimation, and it is estimated that the province has an eruption frequency of 1:10 800 yrs. This research has highlighted a need for further research into the Newer Volcanics Province, as many of the apparently ‘simple’ volcanic centres are likely to be more complex in nature. A spreadsheet database has been made freely available to download for research purposes, along with shapefiles for ArcGIS and kml files for Google Earth.

KEY WORDS:

• Newer Volcanics Province
• monogenetic eruption centres
• intraplate basaltic volcanism

ACKNOWLEDGEMENTS

This paper represents part of the PhD research undertaken by JB under the supervision of Prof. Reid Keays, Dr Ian Nicholls and Dr Patrick Hayman. JB acknowledges a Monash University School of Geosciences research scholarship and Dean's International Postgraduate Research Scholarship. Thanks go to David Higgins for supplying Geoscience Victoria eruption points and Bill Birch (Museum Victoria) for supplying a copy of the Rosengren (1994) report. Jozua van Otterloo (Monash University) is thanked for supplying ArcGIS layer files for the geology of the Mt Gambier subprovince, as is David Moore for helpful discussions relating to geological structures in the NVP. The following Monash University students are thanked for supplying eruption point data for their areas of research, and for the scientific discussions about the NVP during the course of our PhDs: Jozua van Otterloo (Mt Gambier subprovince), Teagan Blakie (Red Rock), Jackson van den Hove (Mt Noorat, The Basins and surrounds, Lake Purrumbete) and Simone Jordan (Lake Purrumbete). Dr Janine Kavanagh (University of Liverpool) supplied eruption point data for Mt Eccles. Thanks go to Teagan Blakie, Jozua van Otterloo and Jackson van den Hove for supplying images of Ecklin Maar, Boyce Hill, Mt Gambier and Lake Purrumbete. Fons VandenBerg is thanked for scientific discussions relating to Geoscience Victoria classifications. Thanks go to Bill Birch, Bernie Joyce, Ian Nicholls, Reid Keays and Ray Cas for in-depth reviewing of this paper and their helpful comments.