The Aboran Sea is an extensional basin of Neogene age that is
surrounded by highly arcuate thrust belts. Multichannel Seismic
(MCS) reflection profile data suggest the basin has a complex
tectonic fabric which includes extensional, compressional and
strike-slip structures. The early Miocene history appears to be
dominated by graben formation with border faults which are in
large part contemporaneous with thrust movements in the
external zones of the Betic and Rif mountains. Extensional tectonics
appear to continue into the late Miocene although the main
movements were probably completed by the time of the
Messinian Òsalinity crisisÓ. The Pliocene and younger history of the
basin is dominated by infilling of the Messinian landscape, gentle
subsidence and, extensional, compressional and strike-slip
movements. There is evidence from the sea-floor morphology and
seismicity patterns that the basin is actively deforming in
response to present day plate motions. Backstripping of well data
suggest that the initial extensional event was accompanied by
crustal and lithospheric thinning. However, the depth to Moho
infered from backstripping is greater than the depth expected
based on seismic and gravity modelling suggesting that the well
data underestimates the true amount of thinning. One explanation
is that some of the thinning occured while the crust was above
sea-level due, say to crustal thickening or lithospheric heating and
thinning prior to rifting. We found that a model with a "normal"
crustal thickness thickness of 31.2 Km, b = 1.4 and a lithospheric
thickness of 50 km predicts 0.8 km of uplift fits the well data and,
brings the backstrip Moho into good agreement with the seismic
and gravity Moho. The origin of such thin lithosphere is not clear
but, we believe that it is related to a regional heating event that
followed detachment of a cold, overthickened, crustal and
lithospheric "root" that formed during the preceeding the Betic, Rif
and Tell orogeny.
Watts, A. B., J. Platt and P. Buhl, Basin Research., 5, 153-177, 1993