Sorbas basin

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A section through the Sorbas basin. See text for explanation.
A section through the Sorbas basin. See text for explanation.

The Sorbas basin is a sedimentary basin around the town of Sorbas in south-east Spain. It is believed to have been formed by extension, between two fault-bounded blocks which rotated anti-clockwise to take up the compression resulting from Europe's collison with Africa. It is filled with turbidites and evaporites dating the the Tortonian-Messinian.

It is a matter of some debate whether the basin dried out at the same time as the main Mediterranean basins.[1][2][3]

[edit] Basin fill

The basin, pictured above, is divided into the following members:

  • At the bottom of the image, the house is constructed on the steep yellow cliffs of the resistant Azagador member.
  • The lower (whiter) and upper (yellower) Abad marls, a Tortonian/Messinian series of turbidites featuring pronounced Milankovic (20,000 year precession) cyclicity, allowing chronostratigraphic dating; these fine muds are easily eroded and form v topography.
  • the Messinian Yesares member, a gypsum evaproite, forming the steep buff bluffs at the top of the valley; there is some debate about how conformable its contact with the Abad marls is.
  • Pliocene deposits, resting unconformably on the top.

[edit] Basin significance

A possible palaeogeographical reconstruction of the Miocene Mediterranian. North to the left. *Red = current coastline *S = Sorbas basin, Spain *R = Rifean corridor *B = Betic corridor *G = Strait of Gibraltar *M = Mediterranean sea
A possible palaeogeographical reconstruction of the Miocene Mediterranian. North to the left.
*Red = current coastline *S = Sorbas basin, Spain
*R = Rifean corridor *B = Betic corridor *G = Strait of Gibraltar *M = Mediterranean sea

The basin was separated from the main Mediterranean basin during the Messinian salinity crisis; therefore the timing of the Yesares member relative to the main basin evaproites is crucial to distinguish between models of how the Mediterranean dried out.

[edit] References

  1. ^ Riding, R.; Braga, J.C.; Marti´n, J.M. (2000). "Late Miocene Mediterranean desiccation: topography and significance of the ‘Salinity Crisis’ erosion surface on-land in southeast Spain: Reply". Sedimentary Geology 133 (3-4): 175-184. doi:10.1016/S0037-0738(00)00039-7. 
  2. ^ Braga, J.C.; Martín, J.M.; Riding, R.; Aguirre, J.; Sánchez-almazo, I.M.; Dinarès-turell, J. (2006). "Testing models for the Messinian salinity crisis: The Messinian record in Almería, SE Spain". Sedimentary Geology 188: 131-154. doi:10.1016/j.sedgeo.2006.03.002. 
  3. ^ Krijgsman, W.; Fortuin, A.R.; Hilgen, F.J.; Sierro, F.J. (2001). "Astrochronology for the Messinian Sorbas basin (SE Spain) and orbital (precessional) forcing for evaporite cyclicity". Sedimentary Geology 140 (1-2): 43-60. doi:10.1016/S0037-0738(00)00171-8. 
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