Similarities between mantle-derived A-type granites and voluminous rhyolites in continental flood basalt provinces
Published:October 01, 2010
Simon Turner, Tracy Rushmer, 2010. "Similarities between mantle-derived A-type granites and voluminous rhyolites in continental flood basalt provinces", Sixth Hutton Symposium on The Origin of Granites and Related Rocks: Proceedings of a Symposium held in Stellenbosch, South Africa, 2- 6 July 2007, John D. Clemens, Colin Donaldson, Carol D. Frost, Alexander F.M. Kisters, Jean-François Moyen, Tracy Rushmer, Gary Stevens
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Many continental flood basalt provinces contain rhyolites with ‘A-type’ compositions and many studies have concluded that these higher silica rocks are crustal melts from metapelitic or tonalitic country rock. However, although many of the low-Ti continental flood basalt sequences exhibit a marked a silica gap from ~55–65 wt.% SiO2, many incompatible element ratios, and the calculated eruption temperatures (950–1100°C) are strikingly similar between the rhyolites and associated basalts. Using experimental evidence, derivation of the low-Ti rhyolites from a basaltic parent is shown to be a viable alternative to local crustal melting. Comparison of liquid compositions from experimental melting...