Seismic observations of transition zone discontinuities beneath hotspot locations

Deuss, A. (2007) Seismic observations of transition zone discontinuities beneath hotspot locations. Special Papers of the Geological Society of America, 430 (Plates). pp. 121-136. DOI 10.1130/2007.2430(07)

Full text not available from this repository.
Official URL: http://www.gsajournals.org/perlserv/?request=get-a...

Abstract

The seismic structure of the transition-zone discontinuities was studied beneath the forty-nine hotspot locations of the catalog of Courtillot et al. (2003), using a global data set of SS precursors. Some of these hotspots are proposed to originate from plumes rising in the upper mantle or from the core-mantle boundary region. I found thin transition zones in approximately two-thirds of the twenty-six hotspot locations for which precursor observations could be made. This observation agrees with the expectation for the olivine phase transition of a systematically thin transition zone in high-temperature regions. Other hotspot locations showed a clear deepening of both the 410- and 660-km discontinuities, which is consistent with a phase transition from majorite garnet to perovskite at a depth of 660 km. Predictions from mineral physics suggest that this transition is more important than the olivine phase transition in regions with high mantle temperatures. So, a hotspot location with a deep 410-km discontinuity in combination with either a shallow or deep 660-km discontinuity might be consistent with hot upwellings rising from the lower into the upper mantle. Hotspot locations with a shallow 410-km discontinuity are not in agreement with a positive thermal anomaly from the surface down to the mantle transition zone. This new interpretation of seismic discontinuities in the transition zone has important implications for our understanding of geodynamics in potential mantle plume location

Item Type: Article
Uncontrolled Keywords: 2007 AREP IA53 2007 P
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Special Papers of the Geological Society of America
Volume: 430
Page Range: pp. 121-136
Identification Number: 10.1130/2007.2430(07)
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:02
Last Modified: 23 Jul 2013 10:06
URI: http://eprints.esc.cam.ac.uk/id/eprint/240

Actions (login required)

View Item View Item

About cookies