Mühendislik ve Doğa Bilimleri Fakültesi Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/1624

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Browsing Mühendislik ve Doğa Bilimleri Fakültesi Koleksiyonu by Publisher "Akdeniz University"

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    Mineralogical and Stable Isotope Properties of Carbonate Minerals in Tuz Gölü Basin (turkey): Paleoenvironment Assessment
    (Akdeniz University, 2018) Çelik Karakaya, Muazzez; Bozdağ, Ayla; Ercan, Hatice Ünal; Karakaya, Necati; Delikan, Arif
    The study area is located south of the Tuz Gölü Basin in the Central Anatolia. The investigated carbonate minerals are deposited in the Neogene lacustrine sediments. Alternations of halite, carbonate, sulfate minerals and clay-enriched levels have been observed in the ten different drillings made in the study area. The aim of this study is to investigate the properties of carbonate minerals closely related to evaporite minerals, e.g. halite and sulfate minerals. The carbonate minerals commonly observed in the region are dolomite and magnesite which are generally micritic and parallel to bedding and also, they have reticulated structures. The thickness of the carbonate minerals precipitate ranges from mm to dm, and the carbonates have been located as a matrix around other minerals in some levels. The thick carbonate levels indicate to rise of lake level or dilution of the water in the lake. In this study, four carbonate facies have been identified as microbial carbonate facies, sparitic facies, pelloidal facies and oolitic facies. Microbial carbonate facies show quite shallow environments and enriched cyanobacteria. The facies are overlain by generally sparitic cemented peloidal limestones. The Mg/Ca ratio of carbonates is quite high and these high values can be explained by dedolomitization processes. The Sr values of the carbonates range from 115-6216 ppm. The δ18O and δ13C isotope values of the dolomite samples from TG6, TG3 and TG2 drillings range from -3.38 to +5.74 ‰, and -10.78 to +0.04 ‰, respectively. Besides, δ18O and δ13C values of magnesite-rich samples vary between 7.57 and 10.46 ‰ and -4.82 and -9.49 ‰. Isotopic values, sedimentological and geochemical data of carbonates indicate that the deposition environment has sometimes been influenced by atmospheric events, wave activity and water level changes, and also biological activities are highly effective in shapka environment.
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    Mineralogical Characterıstıcs of Neogene Sulphate Minerals in the Southern of Tuzgolu Basin, Turkey
    (Akdeniz University, 2018) Çelik Karakaya, Muazzez; Bozdağ, Ayla; Ercan, Hatice Ünal; Karakaya, Necati; Delikan, Arif
    The studied sulfate minerals are located in southern part of Tuz Gölü basin. The Na-Ca-Mg sulfate minerals determined in the basin range from the simple anhydrous salts such as anhydrite, glauberite, thenardite, to simple hydrous salts such as gypsum, eugsterite, starkeite, and also a series variably hydrated Na-Mg sulfates ranging from blöedite, mirabilite and epsomite to löweite. In this study, it has been aimed to investigate the depositional environments and syn-depositional or post-depositional properties of the sulphate minerals. Gypsum is generally the first sulfate mineral formed thermodynamically, and then the gypsum transforms to anhydrite when it just lost two mole H2O. Glauberite is the next sulfate mineral either precipitated with halite or form as a reaction product with anhydrite or gypsum. Mg-sulfate minerals initially precipitate as epsomite then altered to thenardite. Syn-depositional features identified in the sulfate minerals are bed-form structures, vertically oriented euhedral crystals, detrital substrate (siliciclastic sediments), pellets and dissolution or erosion surfaces, and these fabrics have been preserved at the levels including gypsum, anhydrite and glauberite. Porphyroblast, poikilitic growth determined in the sulphate minerals are also typical features of syn-depositional crystallization. Dissolution-reprecipitation features are generally common in gypsum, anhydrite and glauberite minerals which show rounding of euhedral crystals terminations, followed by new syntaxial growth. Additionally, biological processes being syn-depositional feature lead to the form of lenticular minerals. Post-depositional features are very susceptible to alteration caused by increasing in temperature and pressure during burial. Generally, gypsum and epsomite minerals have altered when waters hydration has been released. Disruption and destruction of sedimentary structures have been observed in the levels such as mosaic textures, folds, slabs, fractures, veins. Intrasediment growth of anhydrite nodules has been also detected in all levels of the bore holes. In addition to, different types of several paedomorphic replacements such as gypsum-anhydrite, gypsum/anhydrite-glauberite and glauberite/anhydrite-halite have been determined in the sulfate minerals. Sulfate mineralogy of the Tuz Gölü basin is a key role to understand the water hydrochemistry causing precipitation, and this brine may originate from i) reprecipitation of the Eocene-Oligocene evaporates ii) also inflow of seawater (mixing with non-marine or hydrothermal inflow, and iii) de-dolomitization process.