Anomalously deep mantle transition zone below Central Europe: Evidence of lithospheric instability

The depths of the 410 and 660 km phase transitions provide critical information on the thermal state of the mantle transition zone (MTZ) and, by implication, on the circulation of the upper mantle. We analyze converted seismic waves to produce a high resolution image of these discontinuities beneath...

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Bibliographic Details
Published in:Geophysical research letters 2009-11, Vol.36 (21), p.np-n/a
Main Authors: Hetényi, György, Stuart, Graham W., Houseman, Gregory A., Horváth, Frank, Hegedűs, Endre, Brückl, Ewald
Format: Article
Language:English
Subjects:
Basins
Central Europe
Circulation
Continental dynamics
Discontinuity
Earth Sciences
Earth, ocean, space
Exact sciences and technology
geodynamics
Geophysics
Lithosphere
Lower mantle
Mantle
Miocene
Phase transformations
Plate tectonics
Ponding
Sciences of the Universe
Seismic waves
Seismology
Transition zone
Upper mantle
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Summary:The depths of the 410 and 660 km phase transitions provide critical information on the thermal state of the mantle transition zone (MTZ) and, by implication, on the circulation of the upper mantle. We analyze converted seismic waves to produce a high resolution image of these discontinuities beneath the Pannonian Basin of Central Europe. Models to explain the extension of the basin in the Middle Miocene involve subduction roll‐back and gravitational instability of an over‐thickened lithosphere. We find that cold dense material appears to have accumulated in the MTZ, consistent with the idea of supply from several subduction episodes, or upper mantle overturn. Variation in depth of the 660 km discontinuity by as much as 40 km suggests that cold lithospheric mantle is ponding on top of this phase transition. Where the phase transition is deepest, eventual transfer of this material into the lower mantle may be expected to develop.
ISSN:0094-8276
1944-8007
DOI:10.1029/2009GL040171