The volcanological and petrogenetic origins of the basaltic Flinders Volcanic Province (49–39 Ma), Older Volcanics Provinces, southeast Australia

Abstract

Eocene age basalts within the Mornington Peninsula represent a segment of volcanics constituting the Flinders Volcanic Province, one of the Older Volcanics Provinces, in Victoria, Australia. Section logging at selected coastal sites between Cape Schanck and Flinders, within the Mornington Peninsula National Park, has depicted a succession of gently southeasterly dipping basaltic pahoehoe sheet lavas and localised debris flows, emplaced in a subaerial environment, and distinguished by post emplacement altered weathering horizons. Eight dykes intrude the volcanic succession, controlled structurally by NW normal and NE-trending transform faults of the Gippsland Basin, forming swarms at the West Point Gunnery Range in Flinders, Cairns Bay and Cape Schanck. Geochemical analysis of the lava succession suggest the influence of multiple magma batches, each enriched in light rare earth elements, which based upon Sr–Nd isotopic data came from a long-term incompatible element depleted magma source.

KEYWORDS:

• Flinders Volcanic Province
• Older Volcanics Provinces
• basalt
• dykes
• Pahoehoe lava
• mantle enrichment

ACKNOWLEDGEMENTS

We thank Richard Price and Lin Sutherland for their constructive reviews, which significantly helped improve this manuscript. We also thank Roland Maas for his assistance and expertise concerning TIMS analysis. This research was conducted as part of an Honours research project at Monash University and supported by discretionary research funds of Ray Cas.