Üst Kretase Yaşlı Karababa Formasyonu Fosfat Oluşumlarının Mineralojik, Jeokimyasal Özellikleri Ve Kökeni (Mardin-Mazıdağı)

Abstract

The study investigated phosphate-rich sedimentary rocks in the Late Cretaceous Karababa Formation in the Mardin-Mazıdağ region, which represents the northern part of the Arabian Plate. The stratigraphic succession is divided into three members as i) Karataş: ellipsoidal gray-colored, largely weathered, fossiliferous shelly micritic limestone, ii) Ekinciler: dolomitic cherty limestone interbedded with marls, and iii) Evciler: argillaceous limestone with common phosphatic horizons. Large numbers of hand samples, collected from the outcrop successions, were carefully studied with optic microscopy (OM) and scanning electron microscopy (SEM). They indicate the presence of optical isotropic pelletic apatite minerals (37% P2O5), bone fragments, fish teeth, and invertebrate fossil fragments like brachiopod shells in phosphorite rocks and micritic limestone. The phosphorites in the Karababa Formation are interpreted to have been deposited in a very shallow, near-shore or low energy environment. The X-ray diffraction Üst Kretase Yaşlı Karababa Formasyonu Fosfat Oluşumlarının Mineralojik, Jeokimyasal Özellikleri ve Kökeni (Mardin-Mazıdağı) Mineralogical, Geochemical Properties and Origin of Phosphate Formations in the Upper Cretaceous Karababa Formation (Mardin-Mazıdağı) Sema Tetiker1 , Mesude Yıldırım2 1 Batman Üniversitesi, Madencilik ve Maden Çıkarma Teknolojisi Bölümü 2 Batman Üniversitesi, Fen Bilimleri Enstitüsü Türkiye Jeoloji Bülteni Geological Bulletin of Turkey 64 (2021) 277-308 doi:10.25288/tjb.892186 Sema TETİKER, Mesude YILDIRIM 278 (XRD) method confirmed the presence of apatite (carbonate fluorapatite: CFA), calcite, quartz, rare feldspar, dolomite, and clay (smectite, palygorskite, illite, kaolinite, chlorite, sepiolite, mixed layered illite-vermiculite, and chlorite-vermiculite) in phosphatic, silicic and other carbonate rocks. Total trace element concentrations in apatite minerals range from 2436 ppm to 2456 ppm, with total concentrations normalized to chondrite (ppm) higher than North America Shale Composite (NASC) at 664.98 ppm for P, 208.33 ppm for Sr and 33.66 ppm for Y. Common occurences of apatite, palygorskite/sepiolite, and smectite clay minerals in various sections of the Karababa Formation were interpreted as authigenic minerals in the marine environment. However, occurrences of mixed layered clay minerals were interpreted as a result of neoformation and/or transformation processes. The phosphate occurences in the Karababa Formation are considered to form due to mineral formation processes occurring via biogenic and biogeochemical activities that developed with the changes in sea level linked to tectonic movements associated with the evolution of the Neotethyan ocean during the Upper Cretaceous period.