Continental collision, gravity spreading, and kinematics of Aegea and Anatolia

We have carried out experiments using a layered medium of sand and silicone to investigate the lateral extrusion of a material which spreads over its own weight while being compressed by the advance of a rigid indenter. Boundary conditions in the box mimic those prevailing in the Anatolian-Aegean system. Both shortening in front of the rigid piston, which models the northward motion of Arabia, and extension resulting from the gravity spreading of the sand-silicone layer are necessary to initiate the lateral extrusion. Strike-slip faults accommodate the lateral escape and link the normal faults accompanying gravity spreading with the thrust faults in front of the rigid indenter. Strike-slip faults, begin to accommodate extrusion at a late stage in the experiments after the normal and thrust faults have developed. Experiments also show that the initial geometry of the boundary of the spreading layer may result in the formation of two arcs behind which material extends, in a manner;analogous to the Hellenic and Cypriot arcs, without invoking rheological change at the junction of the two area. The experiments also suggest that southward motion of the eastern part of the spreading region is compensated by the northward advance of the piston, which is a possible explanation for the slower movement of the Cypriot are compared to the Aegean arc.