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| Titel |
The Role of Thermal Effect on Mantle Seismic Anomalies under Laurentia and Fennoscandia from Observations of Glacial Isostatic Adjustment |
| VerfasserIn |
Patrick Wu, Hansheng Wang, Holger Steffen |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074783
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| Zusammenfassung |
| An outstanding issue in the study of seismic tomography is the role of thermal versus
non-thermal (e.g. compositional, partial melting) contribution to seismic velocity anomalies.
Here we use observations of Glacial Isostatic Adjustment (GIA), including global sea levels,
observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission
and GPS crustal uplift rates to show that thermal effect increases from about 65% in the upper
mantle to about 75% in the shallow part of the lower mantle and to about 100% in the deep
lower mantle above the D” layer. This is consistent with temperature excess in
the lower mantle from high core heating. However, the uncertainty increases from
~10% in the upper mantle to ~40% in the shallow lower mantle and is not well
constrained in the deep lower mantle. The implication of large thermal contribution
is that hot buoyant plumes can cause large viscosity reduction which may allow
convection motion to occur easier even if the viscosity in the lower mantle is high. |
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