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Cratonic keels and a 2-layer mantle tested:

Cratonic keels and a 2-layer mantle tested:. Mantle expulsion during Arabia-Russia closure linked to westward enlargement of the Black Sea, formation of the Western Alps and subduction of the Tyrrhenian (not the Ionian) Sea. Miles Osmaston.

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Cratonic keels and a 2-layer mantle tested:

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  1. Cratonic keels and a 2-layer mantle tested: Mantle expulsion during Arabia-Russia closure linked to westward enlargement of the Black Sea, formation of the Western Alps and subduction of the Tyrrhenian (not the Ionian) Sea Miles Osmaston

  2. First: What happens when cratons separate – Greenland-Eureka folding First: What happens when cratons separate? The Greenland- Eureka folding The early Arctic ocean was nearly surrounded by cratons, so the flow of mantle to put under the opening Eurasia Basin ‘dragged’ Greenland’s keel northward in the Eocene, causing major folding across it’s northern neighbours. Osmaston 2006

  3. Opening of the western Black Sea 350km

  4. Vranceaseismicity and shear line? Vrancea seismicity M>3.0(Sperner et al 2001) 180km Transylvania Vrancea mid-Kclosure ? Moesian ‘indenter’ microcraton

  5. Dextral shear zone N of Belgrade S.Karamata (2006) cites this as a part of the dextral shear line Beograd after Kemenci & Canovic 1997

  6. The link with the Alps (Burchfiel) The dextral link with the Alps

  7. Final construction of the Western Alps = Motion 1 of Adria/Italy – 200-250km to WNW - Oligocene W Alps 1 from Osmaston - submitted

  8. Subducting plate down-bend Stepfaulting mechanism of plate down-bend causes………… 1. seismic coupling (alternate step-fault and interface slip) 2. basal Subduction Tectonic Erosion (STE) - development of flat subduction profiles crust of upper plate each step increment traps a sliver of upper plate downbend moves forward

  9. Basal STE: its large-scale action Basal subduction tectonic erosion (STE): its large scale action

  10. Apennines - preparation (seen as widespread sub-CCD turbidites)

  11. Former extent of ‘Greater Adria’ trench line in Cretaceous? Former extent(?) of ‘Greater Adria’ Final line of subduction downbend WHEN ADRIA WAS BEING STE-UNDERCUT IN CRETACEOUS but was further East at the time

  12. Apennines - construction Development of slab pull

  13. Tyrrhenian downbend basins? Downfaulting (a pseudo-trench?) Aeolianarc 100 km After Gamberi & Marani 2006

  14. Overthrusting of Calabria-Peloritani All have been overthrust from the direction of the Tyrrhenian Sea. This has induced strong epeirogenic response in blocks of mature continental crust, (which have not been displaced). 250km Episodes 2004

  15. Seismicity Wortel & Spakman 2000 <40km Jenny et al 2006 Mainly intracrustal (thermal) epeirogenic adjustments following overthrusting Where does >800km of slab length come from if it was Ionian?

  16. Did Tyrrhenian slab pull drive the swing of Corsica-Sardinia? from Geological Map of Europe 1:5M, 2005

  17. Opening of the western Black Sea - reprise 350km

  18. Conclusions • Mantle flow expelled from between the converging Russia-Arabia cratons HAS driven the keel of Moesia westwards, and is still active (Vrancea). • In the Oligocene this action drove the Balkans ~200km westward. This built the Western Alps and started Apennines construction by reactivating Cretaceous subduction and triggering Tyrrhenian slab pull. • Since mid-Cretaceous or earlier, this action has driven or triggered E-W components of closure in Mediterranean belts. • N-S closure in the East was the primary agent, so N-S compression was present too.

  19. Apparently these two primary directions were indeed operative in Apennines construction Guisy Lavecchia 1988

  20. So I conclude that the Earth does indeed have a 2-layer mantleand(at least some) cratonic keels that reach nearly to the 660. Thank you

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