New insights on Messinian evaporites based on field and seismic interpretations in the Neogene Antalya Basin, SW Turkey

Authors: SALİHA DÜNDAR, BAKİ ERDOĞAN VAROL

Abstract: In situ/primary Messinian upper evaporite is absent in the onland (onshore) sections of the Aksu and Manavgat subbasins (Antalya Basin), where gypsum blocks, gypsum conglomerate, and laminated gypsum beds mixed with siliciclastic materials are collectively present in the uppermost Messinian-?lowermost Pliocene succession. The metric-size resedimented evaporite blocks, mainly derived from selenite-dominated marginal/upper evaporite, were deposited time-equivalent to the lower-middle parts of the reefal Gebiz limestone in the Aksu subbasin. Resedimented bedded evaporites were accumulated after siliciclastic-dominated (fluvio-deltaic) sedimentation of the Taşlık Formation in the Manavgat subbasin (nearby Antalya city). Some bedded/?resedimented gypsums were defined within the Gebiz limestone and the Eskiköy Formation, as observed in the logs of the Aksu-1, Manavgat-1, and Manavgat-2 wells. Effects of the Messinian salinity crisis are seen on the seismic boundary of the Messinian erosional surface in the Aksu subbasin resting directly on the Karpuzçay Formation and in the lower and middle parts of the fluvio-deltaic Eskiköy Formation and reefal Gebiz limestone. As for the Manavgat subbasin, Manavgat-1 and -2 well logs indicate the existence of bedded/?resedimented evaporites in the Taşlık and Eskiköy Formations, which is supported by the seismic sections. Additionally, onshore and offshore seismic sections indicate that the upper evaporite layer could be traceable both in onshore and offshore areas. The relationship between evaporite and nonevaporite units is explained by the Aksu phase, which caused compressional deformation leading to significant uplift in the region around the Gebiz High. This uplift is also involved in relative sea-level drop, which resulted in alternating deposition between siliciclastic (Eskiköy and Taşlık Formations), resedimented-bedded gypsum, and transgressive shallow marine reefal Gebiz limestone.

Keywords: Miocene-Pliocene, Aksu-Manavgat subbasins, evaporite, seismic, well logs

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