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www.solid-earth.net/2/25/2011/
doi:10.5194/se-2-25-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
A Mesoproterozoic continental flood rhyolite province, the Gawler Ranges, Australia: the end member example of the Large Igneous Province clan
1GEMOC, Earth and Planetary Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
2School of Geosciences, Monash University, Melbourne, 3800, Australia
3School of Geology and Geophysics, Adelaide University, Adelaide, SA, 5001, Australia
Abstract. Rhyolite and dacite lavas of the Mesoproterozoic upper Gawler Range Volcanics (GRV) (>30 000 km3 preserved), South Australia, represent the remnants of one of the most voluminous felsic magmatic events preserved on Earth. Geophysical interpretation suggests eruption from a central cluster of feeder vents which supplied large-scale lobate flows >100 km in length. Pigeonite inversion thermometers indicate eruption temperatures of 950–1100 °C. The lavas are A-type in composition (e.g. high Ga/Al ratios) and characterised by elevated primary halogen concentrations (~1600 ppm fluorine, ~400 ppm chlorine). These depolymerised the magma such that temperature-composition-volatile non-Arrhenian melt viscosity modelling suggests they had viscosities of <3.5 log η (Pa s). These physicochemical properties have led to the emplacement of a Large Rhyolite Province, which has affinities in emplacement style to Large Basaltic Provinces. The low viscosity of these felsic magmas has produced a unique igneous system on a scale which is either not present or poorly preserved elsewhere on the planet. The Gawler Range Volcanic Province represents the erupted portion of the felsic end member of the family of voluminous, rapidly emplaced terrestrial magmatic provinces.
Final Revised Paper (PDF, 25773 KB) Discussion Paper (SED)
Citation: Pankhurst, M. J., Schaefer, B. F., Betts, P. G., Phillips, N., and Hand, M.: A Mesoproterozoic continental flood rhyolite province, the Gawler Ranges, Australia: the end member example of the Large Igneous Province clan, Solid Earth, 2, 25-33, doi:10.5194/se-2-25-2011, 2011. Bibtex EndNote Reference Manager XML
