Pliocene Burdur basin, SW Turkey: tectonics, seismicity and sedimentation

Abstract

The Pliocene Burdur Formation of SW Turkey was deposited in a NE-SW trending half-graben with a major basement fault along its SE margin. Hangingwall-sourced fans were confined proximally by basement topography. Distally, they developed 'ideal' fan geometries. These fans became submerged by the lake that occupied the centre of the basin. This transgression was caused by the migration, with time, of the hangingwall pivot away from the basin-controlling fault. Footwall-sourced fans exhibit three distinctly different geometries. At the northern end of the basin a wide braidplain developed due to the rapid erosion of both penecontemporaneous volcaniclastic deposits to the east and the footwall crest of a newly formed fault within the basin. Along the footwall scarp in the central part of the basin a narrow bajada formed. In the south, a large alluvial fan had its source in the relay structure between two left-stepping en echelon fault segments. The small size of footwall-sourced fans compared with those sourced on the hangingwall slope was due to rapid subsidence of the basin floor adjacent to the footwall scarp. Although this suggests high levels of seismicity, the general paucity of wet-sediment deformation within the Burdur Formation indicates that seismicity in the Burdur region during the Pliocene was more subdued than at present.