No abstract

The Aşkale sub-basin hosts Early Miocene evaporites intercalated with clastic sediments and carbonates. Gypsumand anhydrite-rich evaporite samples are characterized by high CaO and SO4 contents, and low Na2O, K2O, MgO, and B contents. The Sr contents are 228-13100 ppm in evaporite samples, 169-992 ppm in claystone, 181-60090 ppm in marl, and 15150 ppm in limestone. All the samples are also characterized by enrichment in light rare earth elements (REE) with LaN/LuN = 0.667-4.243 and have variable CeN/Ce* (0.823-1.353) ratios. Measured EuN/Eu* values of the samples display strong and variable negative and positive Eu anomalies. δ 34 SCDT and δ 18 O values of gypsum-and anhydrite samples have wide ranges from 21.30 ‰ to 25.62 ‰, and 11.5 ‰ to 19.1 ‰, respectively. Most of these values are heavier than expected Miocene marine gypsum composition and may be resulted from reduction and oxidation reactions of sulfide species in brines. 87 Sr/ 86 Sr ratios range from 0.707475 (ΔSW = −169.8) to 0.708175 (ΔSW = −99.8), close to and/or slightly lower than an Early-Miocene marine isotopic composition. Petrochemical and isotopic data indicate that the Aşkale basin evaporites developed in subtropical conditions via multiple marine transgressions onto a shallow platform or lagoonal environment.