Sedimentation and neotectonics of the Burdur region, southwest Turkey.

The NE-SW trending Burdur-Acig?l-Baklan basin system of southwest Turkey represents the present-day configuration of a system initiated in late Miocene / early Pliocene times. During the Pliocene a half-graben, controlled by a NW-dipping planar fault system, developed in the area around Burdur. The Burdur Formation was deposited in this half-graben. Rapid subsidence is indicated by the lack of a well-developed footwall-sourced fan system. However, larger fans developed in the relay structures between en echelon fault segments. The centre of the basin was occupied by a deep saline lake. Orbitally-driven climatic change was the dominant control on sedimentation in this lake. The scarcity of wet-sediment deformation within the Burdur Formation suggests that levels of Pliocene seismicity were lower than twentieth century levels. Towards the end of the Pliocene the fault system controlling the Burdur basin became inactive and renewed faulting took place in the hangingwall of the old system. This event gave rise to the present-day configuration of narrow basins in the study area and was due to instability of the end-Pliocene topography. Both margins of the present-day Burdur, Acig?l and Baklan basins are faulted. In each case the major throw is on the fault on the southeast margin. A ? value of 1.18 calculated for the Burdur region assumes a planar fault geometry. As a curvature of up to 40 at depth cannot be ruled out this must be considered a minimum estimate. Each of the Burdur, Acig?l and Baklan basins is extending in a NW-SE direction (compared to the N-S extension direction of the Aegean). It is proposed that the basins are within a N-S trending deforming zone between the rapidly-extending Aegean region (to the west) and the relatively stable Anatolian plateau (to the east). The model adopted explains the clockwise rotation of fault-bounded blocks in the Burdur region. The dextral motion across the deforming zone, predicted by the model, may be a result of the anticlockwise rotation of western Turkey.