Paleobathymetric evolution of the Miocene deposits of the Gömbe sector of the Lycian Foreland and Aksu basins in Antalya, Turkey

Abstract

The evolution of the Lycian Foreland and Aksu basins are associated with the Africa-Eurasia convergence and collisionof intervening continental blocks. Both basins developed around the Beydağları, a Mesozoic carbonate platform, which constitutesthe main component and western limb of the Isparta Angle. The Gömbe Basin is an integral part of the Lycian Foreland Basin thatcomprises mainly Eocene to Late Miocene turbidites, onto which the allochthonous Lycian and Antalya nappes thrust over. The AksuBasin, however, developed in the inner part of the Isparta Angle and is bounded by the Aksu Thrust in the east. During their evolution,these basins experienced significant bathymetric changes, possibly due to vertical motions and variations in the sediment supply. Thisstudy provides a detailed analysis of the paleobathymetric evolution of these basins. This conducted paleobathymetric study was basedon the determination of the depositional depth by the abundance ratio of planktonic versus benthic foraminifera, which is the functionof the water depth. The percentage of planktonic foraminifera relative to the total foraminifer population (%P) increases from shallowto deep water. However, some benthic foraminifera species are directly affected by the oxygen level of the bottom water, rather thanby paleobathymetry, i.e. stress markers, and were discarded in the calculation. Additionally, the dissolution of the foraminifera has thepotential for miscalculations, since planktonic foraminifera are more prone to dissolution than benthic ones. Nevertheless, the obtainedquantitative results were verified and validated qualitatively by specific benthic depth markers that lived at specific depth ranges. AksuBasin had a shallowing trend, and the sedimentation rate exceeded the subsidence in the middle of the section. Calculated depths forthe Gömbe Basin indicated depths around 1000 m, which was contrary to the high sedimentation rates indicated by the turbiditic faciesof the basin infills.