American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 193766 bytes)    Cited by

GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L07311, doi:10.1029/2005GL022360, 2005

Beyond the thermal plume paradigm

C. G. Farnetani

Institut de Physique du Globe, Paris, France


H. Samuel

Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA


Abstract

Geodynamic models of thermo-chemical plumes rising in a mantle wind suggest that we should abandon some paradigms based on the dynamics of purely thermal axisymmetric plumes. The head-tail structure is possible but not unique and the lack of a plume head does not preclude a deep origin. Our results suggest that the surface expression of some thermo-chemical plumes may be a headless, age-progressive volcanic chain. Plume tails are laterally heterogeneous, rather than concentrically zoned, because deep heterogeneities are sheared into distinct and long-lasting filaments that will be successively sampled by different volcanoes, as the oceanic plate moves over the plume tail. Finally, calculated S-wave velocity anomalies are consistent with recent plume tomographic images, showing that compositional heterogeneities in the lowermost mantle favour the coexistence of a great variety of plume shapes and sizes.

Received 5 January 2005; accepted 15 March 2005; published 14 April 2005.

Index Terms: 7208 Seismology: Mantle (1212, 1213, 8124); 8121 Tectonophysics: Dynamics: convection currents, and mantle plumes; 8137 Tectonophysics: Hotspots, large igneous provinces, and flood basalt volcanism.

Read Full Article (file size: 193766 bytes)    Cited by

Citation: Farnetani, C. G., and H. Samuel (2005), Beyond the thermal plume paradigm, Geophys. Res. Lett., 32, L07311, doi:10.1029/2005GL022360.