Optically stimulated luminescence (OSL) dating of quartz grains within the sand dykes cutting the lacustrine deposits in the Burdur area (SW Turkey) and its tectonic interpretation

Abstract

Burdur city is located on a lacustrine sedimentary deposit at the northeastern end of the Fethiye–Burdur Fault Zone (FBFZ) in SW Turkey. Fault steps were formed in response to vertical displacement along normal fault zones in these deposits. Geological, tectonic, mineralogical investigations and age analysis were carried out to identify the liquefied material. Paleoliquefaction characterized by sand and mud dykes is observed in three different locations. For this study, in order to investigate the relationship of sand and mud dykes with liquefaction, the present geologic and hydrogeologic environment, evolution of the host sediments and the paleoenvironment corresponding to duration of liquefaction were investigated. Field work was carried out and laboratory experiments were performed on the samples taken from liquefied soils and clayey lacustrine sediments cut by sand and mud dykes. The mineralogical features of the clays and age analysis of the liquefied materials were examined in the experimental studies. As a result of the X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) micrographs, the liquefied clay mineral assemblage in the soil samples contains illite. Optically stimulated luminescence (OSL) dating analysis has indicated an age ranging from 15,161 ± 744 to 17,434 ± 896 years for the liquefaction features. Assuming the groundwater level to be at critical depth, it was concluded that there was no possibility of liquefaction in most parts of the settlement during an earthquake.