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Lithosphere in the Mediterranean region

Lithosphere in the Mediterranean region. László Lenkey MTA-ELTE Geological, Geophysical and Space Science Research Group. Layout of the talk. Definition of the lithosphere Methods to study the lithosphere Thickness of the lithosphere in Europe

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Lithosphere in the Mediterranean region

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  1. Lithosphere in the Mediterranean region László Lenkey MTA-ELTE Geological, Geophysical and Space Science Research Group

  2. Layout of the talk • Definition of the lithosphere • Methods to study the lithosphere • Thickness of the lithosphere in Europe • Bearing of the tectonics on the lithospheric thickness, and heatflow

  3. Definition of the lithosphere • The lithosphere is the outer shell of the earth which remainsrigidduring geological time.

  4. Definition of the lithosphere • Mechanical lithosphere • Thermal lithosphere • Elastic lithosphere

  5. Mechanical lithosphere • The mechanical lithosphere is defined to be those rocks that remain a coherent part of the plates on geological time scale. A typical definition would be rocks that cannot be deformed more than 1% in 108 yr at typical mantle stress levels. The deformation of the mantle is determined by its viscosity, and its viscosity is in turn, determined by its temperature. The base of the mechanical lithosphere is prescribed by an isotherm, typically 1400 K.

  6. Thermal lithosphere • The oceanic lithosphere is taken to be the upper thermal boundary layer of mantle convection

  7. Thermal lithosphere Models of mantle convection in spherical shell geometry Ra=10e6 Ra=10e7 Herein et al., 2008

  8. Thermal lithosphere Herein et al., 2008

  9. Thermal lithosphere Mantle geotherms from Schubert et al., 2001

  10. Thermal lithosphere How thick is the thermal boundary layer?

  11. Thermal lithosphere How thick is the thermal boundary layer? Parsons and Sclater, 1977

  12. Definition of the lithosphere TBL in our sense mechanical BL by McKenzie 1978 TBL by McKenzie 1978

  13. Elastic lithosphere

  14. Elastic lithosphere

  15. Methods to investigate the lithosphere • Seismic methods • Magnetotelluric soundings • Thermal (and integrated gravity) modelling

  16. Seismic methods P wave S wave Rayleigh wave Love wave

  17. Seismic methods What makes seismic methods suitable to detect the LAB? • SNA = Canadian Shield • TNA = tectonic western North America • ATL = northeastern Atlantic from Schubert et al., 2001

  18. Seismic methods

  19. Seismic methods

  20. Seismic methods Global tomographic models for Europe from Artemieva et al. 2006, Vp after Bijward and Spakman 2000 Vs after Shapiro and Ritzwoller 2002

  21. Seismic methods from Artemieva et al. 2006

  22. Seismic methods Babuska et al. 1988

  23. Magnetotellurics ECORS-Central Pyrenees profile 2D electrical resistivity model from MT from Transmed Atlas, after Munoz et al. 2002

  24. Magnetotellurics 2D resistivity model derived from MT soundings along the PGT-1 profile in the Pannonian basin Ádám et al. 1996

  25. Thermal modelling

  26. Thermal modelling Combined with gravity modelling Zeyen and Fernandez, 1994

  27. Thermal modelling Heat flow in Europe Thickness of the thermal lithosphere Pollack et al. 1993 Artemieva 2003

  28. Thickness of the lithosphere in Europe from Artemieva et al. 2006

  29. Thickness of the lithosphere in Europe from Artemieva et al. 2006

  30. Thickness of the lithosphere in Europe from Artemieva et al. 2006

  31. Lithospheric thickness in the Pannonian basin P-wave residuals of Babuska et al. 1988 were revised by Horváth, 1993, MT soundings are after Praus et al. 1990, and Ádám 1976-1996, central part is modified by Lenkey 1999

  32. Lithospheric thickness in the Pannonian basin Horváth et al. 2005

  33. Tomography in the Alps Lippitsch et al. 2003

  34. Tomography in the Alps Lippitsch et al. 2003

  35. Tomography in the SE Carpathians Martin et al. 2005

  36. Relationship between the formation of back arc basins and the lithospheric structure inthe Mediterranean region Horváth et al. 2005

  37. Relationship between the formation of back arc basins and the lithospheric structure inthe Mediterranean region Piromallo and Morelli 2003

  38. Regional P wave tomography in Europe Piromallo and Morelli 2003

  39. Regional P wave tomography in Europe Piromallo and Morelli 2003

  40. Regional P wave tomography in Europe Piromallo and Morelli 2003

  41. Summary • The lithosphere is the upper thermal boundary layer of the mantle convection • The lithosphere can be investigated by seismic, magnetotelluric methods and thermal modelling • These methods do not always result the same lithopsheric thickness • The thin lithosphere in the Mediterranean region correlates well with the areas characterized by high heat flow • These are the areas which suffered back-arc extension during the Paleogene-recent time

  42. Seismic anisotropy

  43. Seismic anisotropy

  44. SKS splitting results 1 sec Stuart et al. 2007, CBP

  45. Formation of back-arc basins

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