Fluid dynamics of mantle plumes

Abstract

A 'hotspot' (Wilson 1963) is a long-term source of volcanism which is fixed relative to the plate overriding it. Common signatures of hotspots include a bathymetric swell and an associated gravity anomaly; basalt geochemistry different from normal mid-ocean ridge basalts; and volcanic chains with a clear age progression parallel to the plate motion, in some cases beginning with a voluminous flood basalt event (Morgan 1972). The total number of hotspots is controversial, but is probably around 40-50 (Richards et al. 1988; Sleep 1990) of which 8 or 9 are associated with flood basalts (Richards et al. 1989; Courtillot et al. 2003). Petrological (e.g. White and McKenzie 1995) and geophysical (e.g. Sleep 1990) studies suggest that hotspot material is 150-300 K hotter than the normal mantle, while flood basalts are associated with excess temperatures up to 400 K (e.g. Thompson and Gibson 2000). © 2007 Springer-Verlag Berlin Heidelberg.