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. Bound ary conditions in the box mimic those prevailing in the Anatolian-Aegean sy stem. Both shortening in front of the rigid piston, which models the northw ard motion of Arabia, and extension resulting from the gravity spreading of the sand-silicone layer are necessary to initiate the lateral extrusion. S trike-slip faults accommodate the lateral escape and link the normal faults accompanying gravity spreading with the thrust faults in front of the rigi d indenter. Strike-slip faults, begin to accommodate extrusion at a late st age in the experiments after the normal and thrust faults have developed. E xperiments also show that the initial geometry of the boundary of the sprea ding layer may result in the formation of two arcs behind which material ex tends, in a manner;analogous to the Hellenic and Cypriot arcs, without invo king rheological change at the junction of the two area. The experiments al so suggest that southward motion of the eastern part of the spreading regio n is compensated by the northward advance of the piston, which is a possibl e explanation for the slower movement of the Cypriot are compared to the Ae gean arc.