Neotethyan marine legacy and recycled sulfates in a continental sabkha: multi-proxy insights from the Middle Miocene Bozdoğan gypsum, Western Anatolia
Journal of African Earth Sciences, cilt.242, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 242
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jafrearsci.2026.106266
- Dergi Adı: Journal of African Earth Sciences
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Geobase, INSPEC, Zoological Record
- Anahtar Kelimeler: Geochemistry, Middle miocene, Neotethys, Paleoclimate, Sabkha–lake system, Sulfur–oxygen–strontium isotopes, Western Anatolia
- Van Yüzüncü Yıl Üniversitesi Adresli: Evet
Özet
Middle Miocene (Langhian–early Serravallian) clastic- and carbonate-bearing gypsum deposits in the Bozdoğan–Yazıkent Basin (Western Anatolia) record evaporite formation within a tectono-sedimentarily confined, semi-closed lake–sabkha system developed during the Middle Miocene Climatic Optimum (∼17–14 Ma). Integrated sedimentological, mineralogical, elemental, and isotopic data (δ34S, δ18O, δ13C, 87Sr/86Sr) indicate that gypsum precipitation was governed by evaporative concentration, groundwater reflux, and repeated anhydrite↔gypsum cycling driven by orbitally paced wet–dry oscillations. Facies associations including selenitic–chevron, laminated, nodular/chicken-wire, alabastrine–massive, gypsarenite, and satin-spar gypsum reflect shallow, seasonally variable hypersaline conditions across a lake-center to marginal sabkha mosaic. Gypsum δ34S (+18.0 to +19.4‰) and δ18O (+11.8 to +20.5‰) values record intense evaporation and diagenetic overprinting, with only minor geothermal or microbial influence. In contrast, marine-like 87Sr/86Sr ratios (0.70866–0.70877) closely match Middle Miocene seawater, providing compelling evidence for efficient recycling of Neotethyan marine sulfate into a continental basin via groundwater-mediated dissolution and transport of older marine evaporites, rather than direct marine incursions. Carbonate (δ13C = −5.74 to −4.42‰; δ18O = −8.57 to +5.03‰) values indicate organic-matter oxidation, meteoric water input, and early diagenetic modification. Major and trace element patterns and ratios (e.g., Sr/Ba> 20, U/Th > 1.25, Fe2O3/MnO> 10) suggest fluctuating oxic–suboxic pore-water conditions and progressive evaporative concentration under an arid to semi-arid paleoclimate. These results demonstrate that continental lake–sabkha systems can preserve a marine-derived sulfate signature without coeval marine conditions. The Bozdoğan succession thus provides a new multi-proxy framework for interpreting marine-like isotopic signatures in inland evaporites and offers important insights into Middle Miocene paleogeography, hydrology, and biogeochemical cycling in Western Anatolia and the Eastern Mediterranean region.