Continental tholeiitic flood basalt provinces

Abstract

Large areas of the continents appear to have been covered by vast thicknesses of laterally extensive basaltic lava flows at various stages during the past 1000 Ma, apparently fed from fissures rather than central vent volcanoes. These are referred to as continental flood basalt provinces or CFBs. Originally they were considered to be characterized by the eruption of chemically uniform Fe-rich tholeiitic basalts (Kuno 1969). However, as we shall see in Section 10.6, more recent studies have revealed significant chemical diversity within individual provinces. Nevertheless, most are dominated by eruptions of relatively evolved tholeiitic basalts which show some similarity in terms of their mineralogy and major element chemistry to MORB (Ch. 5), although their trace element characteristics are more akin to those of enriched MORB and oceanic-island tholeiitites (Ch. 9). Next to MORB, they form the largest volcanic features on Earth and like MORB are also generated in extensional tectonic environments.