Revealing the Deformation of SW Anatolia (Turkey) by Anisotropy of
Magnetic Susceptibility (AMS) Data
Abstract
Convergence between the Eurasian and the African plates in the West
Anatolian-Aegean region results in a trench retreat due to slab
roll-back and tearing of the subducted African lithosphere. The upper
plate response of this process gave way to back-arc extension in the
region. In this context, we have conducted a very rigorous AMS study on
the Neogene units in SW Anatolia to unravel the style and amounts of
deformation. For this purpose, from 83 sites in 11 structurally
homogeneous domains, 1680 paleomagnetic samples were analyzed. Obtained
results are used to determine principal strain directions to unravel
overall deformation styles and amounts in the region.
The results have shown that AMS is related to the tectonic deformation,
which facilitated that the AMS directions correspond to cumulative
principal strains. Maximum susceptibility is parallel to the major
extension (k), minimum susceptibility (k) corresponds to compaction
after deposition, almost always normal to the bedding plane. The
intermediate axis (k) found to be parallel to a second extension
direction that the region has been under the control of
multi-directional extension during Neogene.
Two mean anisotropy directions are identified. These are
Oligocene-Middle Miocene NW-SE, and Late Miocene-Pliocene NE-SW directed
extension. The mean anisotropy directions are generally parallel or
perpendicular to the general strikes of the normal faults. The results
have shown that the deformation in the region resembles to
differentially stretched rubber sheet under the influence of SW directed
extension exerted by the southwards retreating Eastern Mediterranean
subduction system.