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Published November 15, 2000 | Submitted + Published
Journal Article Open

The thermal state of the upper mantle; No role for mantle plumes


A variety of geophysical data indicates that long wavelength temperature variations of the asthenosphere depart from the mean by ±200°C, not the ±20°C adopted by plume theoreticians. The 'normal' variation, caused by plate tectonic processes (subduction cooling, continental insulation, 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 1400°C. Asthenospheric convection at ridges, rifts and fracture zones and at the onset of continental breakup is intrinsically 3D, giving rise to shallow pseudoplume‐like structures without deep thermal instabilities. Deep narrow thermal plumes are unnecessary and are precluded by uplift and subsidence data. The locations and volumes of 'midplate' volcanism appear to be controlled by lithospheric architecture, stress and cracks.

Additional Information

© 2000 by the American Geophysical Union. Received 24 February 2000; accepted 29 September 2000. This paper represents Contribution Number 8702, Division of Geological and Planetary Sciences, California Institute of Technology. This work has been supported by NSF Grant EAR 9726252.

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August 19, 2023
October 19, 2023