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The Thermal State of the Upper Mantle; No Role for Mantle Plumes

Summary: The Thermal State of the Upper Mantle;
No Role for Mantle Plumes
Don L. Anderson
California Institute of Technology
Seismological Laboratory 252-21
Pasadena, CA 91125 U.S.A.
TEL: 626.395.6901
FAX: 626.564.0715
E-mail: dla@gps.caltech.edu
A variety of geophysical data indicates that long wavelength temperature variations of the
asthenosphere depart from the mean by 200C, not the 20C adopted by plume theoreticians.
The `normal' variation, caused by plate tectonic processes, such as subduction cooling,
continental insulation and small-scale convection, encompasses the temperature excesses that
have been attributed to hot jets and thermal plumes. Geophysical estimates of the average
potential temperature of the upper mantle are about 1400C. Asthenospheric convection at
ridges, rifts and fracture zones and at the onset of continental breakup is intrinsically 3D, giving
rise to shallow pseudo-plume-like structures without deep thermal instabilities. Deep narrow
thermal plumes are unnecessary and are precluded by uplift and subsidence data, and widespread


Source: Anderson, Don L. - Division of Geological and Planetary Sciences, California Institute of Technology


Collections: Geosciences