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    Depositional environment characteristics of UlukA +/- AYla Evaporites, Central Anatolia, Turkey
    (SPRINGER, 2017) Keskin, Seref; Sener, Mehmet; Sener, Mehmet Furkan; Ozturk, Muhammed Zeynel
    This paper examines evaporated deposits of gypsum known as the UlukA +/- AYla Evaporites located in the UlukA +/- AYla Basin, central Anatolia, Turkey. The Late Eocene compression between the Eurasian and Afro-Arabian plates formed numerous shallow epicontinental basins in SE central Anatolia. During this period, the UlukA +/- AYla Basin was a shallow marine environment. The composition of the UlukA +/- AYla Basin indicates that gypsum and stromatolite were deposited due to an arid climate and sea level oscillation between 37.25 and 38.52 Ma. Oxygen, sulfur, and strontium isotopes and the geochemistry of the evaporated rocks were measured to understand the paleoenvironment of this formation. Trace element analyses of Fe, K, Mg, Na, Mn, Sr, Ni, and Cu from the gypsum samples showed very high variability. The average K/Na, Sr/Ca, and Mg/Na were measured to be 0.4, 2.35, and 2.9 %, respectively, which indicates that the UlukA +/- AYla gypsum lies in a formerly hypersaline environment. Sr-87/Sr-86, O-18, and S-34 isotope ratios indicate that the gypsum was deposited in marine water then mixed with fresh continental water.
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    Distribution and accumulation of heavy metals in the sediments of Akkaya Dam, Nigde, Turkey
    (SPRINGER, 2012) Keskin, Seref
    Twenty-one surface sediment samples were collected from Akkaya Dam. Heavy metal concentrations (Mo, Cu, Pb, Zn, Ni, Co, Mn, Fe, Cr, As, V and Cd), grain size, organic carbon and carbonate contents were studied in order to assess the extent of environmental pollution and to discuss the origin of these contaminants in sediments of dam. The sediments in the study area are mostly very fine sands. However, mud was observed in the northeast of the dam. Sediment pollution assessment was carried out using enrichment factor. The calculation of enrichment factors showed that Mo is depleted by 1.0 whereas Cu, Pb, Zn, Ni, Co, Mn, As, V, Cr and Cd are enriched by 3, 5.4, 7, 2.7, 2.2, 3.4, 42.3, 2.1, 1.8 and 7.2, respectively. Relatively high concentrations heavy metals occurred in north (textile industry area) and east (Karasu River) due to enrichment controlled by anthropogenic wastes. The results of correlation analysis show low-medium positive and negative correlations among metals, grain size, carbonate contents and organic carbon and indicate that heavy metals in sediments of the Akkaya Dam have different anthropogenic sources.
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    Geochemistry of camardi Formation sediments, central Anatolia (Turkey): implication of source area weathering, provenance, and tectonic setting
    (GEOLOGICAL SOCIETY KOREA, 2011) Keskin, Seref
    The upper Cretaceous-Eocene Camardi Formation is exposed along the northern edge of the Ulukisla Basin (central Anatolia) and consists of turbiditic sediments. The sediment geochemistry has been studied in order to understand the provenance, source area weathering, and tectonic setting of the basin. Camardi Formation sediments are characterized by low to moderate SiO2 contents, variable abundances of major elements, and a relatively high proportion of ferromagnesian elements. Evidence from discrimination diagrams of sedimentary provenance, tectonic setting, major element geochemistry and Sc/Th, Cr/Th, Co/Th, Zr/Sc, La/Sc, La/Co, Cr/Sc, Y/Ni, and K/Rb values show that the Camardi Formation sediments were derived from mafic, felsic, and intermediate sources. The chemical index of alteration (CIA: 57.63-78.11) revealed moderately weathered source rocks. Then major and trace element concentrations indicated deposition in an active continental margin and continental island arc settings.
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    Grain size and heavy mineral distribution as related to hinterland and environmental conditions for modern beach sediments from the Gulfs of Antalya and Finike, eastern Mediterranean
    (ELSEVIER SCIENCE BV, 2007) Ergin, Mustafa; Keskin, Seref; Dogan, A. Umran; Kadioglu, Yusuf Kaan; Karakas, Zehra
    Backshore sediment samples from 22 beaches along the Antalya and Finike Gulfs have been studied for their grain size, chemical and heavy mineral composition. Data presented here suggest that well- to moderately-sorted (0.41 Phi-0.92 Phi) medium sand (1 Phi-2 Phi) represents dominant mean grain size in most beaches. In contrast, some beaches from the western part of the Gulf of Antalya (Goynuk, Kemer-Kiris and Beldibi) are composed of pebble- to boulder-size grained beaches which are located close to mouths of short and steep-gradient ephemeral rivers entering the sea from the Western Taurus Mountains. The heavy mineral assemblages are dominated by detrital opaque minerals (14-58% magnetite, chromite, and hematite), pyroxene (8-65% augite), amphibole (3-15% tremolite and actinolite), epidote (3-25%), garnet (2-9% pyrope and almandine) and micas (3-20 biotite, muscovite and chlorite). The very high concentrations of heavy minerals (up to 86% of bulk sediment) together with the significant concentrations of some elements found in beach sediments from the Gulf of Finike and western Gulf of Antalya (Fe: 18.40%; Cr: 10.00%; and Ti: 1.32%) are indicative of ultramafic origin, mainly derived from the ophiolitic rocks of the Antalya-Tekirova nappe on coastal hinterland. (c) 2007 Elsevier B.V. All rights reserved.
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    Late Quaternary climate and sea-level changes recorded in sediment composition off the Buyuk Menderes River delta (eastern Aegean Sea, Turkey)
    (PERGAMON-ELSEVIER SCIENCE LTD, 2007) Ergin, Mustafa; Kadir, Selahattin; Keskin, Seref; Turhan-Akyuz, Nilufer; Yasar, Dogan
    Influences of Holocene climatic and sea level changes on sedimentation on the continental shelf off the Buyuk Menderes River delta, SW Turkey were investigated using grain size and X-ray clay mineralogical data on surficial and 14C-dated core sediments collected at 19-81 m water depths. Modern, fine-grained, siliciclastic sediments cover most of the seafloor of inner to mid-shelf areas. A narrow, relict belt extends from northwest to south (at 66-81 m water depths), where sediments are characterized by abundant sand and gravel (27-52%) and biogenic carbonate (16-44%) contents, and microscopic examination suggests an older origin. The radiocarbon ages of mid and lower sections in cores (3670-10,380 yr BP) reflect sedimentation under depositional conditions from early to late Holocene in the study area. Additionally, downcore changes of grain size toward coarser-grained sediments most probably record global climatic effects with sea level changes, specifically the transition from lowstand in early Holocene to highstand at mid-late Holocene. The presence of this relict belt in offshore waters can be attributed largely to active uplift tectonics. The coarser-grained relict belt, compared with available seismic profiles, corresponds to an lowstand unconformity of bottomset beds of the prograding Buyuk Menderes Delta. Reconstruction from nautical charts clearly showed the presence of an E-W-trending submarine canyon ("Paleo-Buyuk Menderes River valley") in the course of Buyuk Menderes Graben. This is interpreted as product of combination of sea-level lowstands and subsidence tectonics throughout the late Quaternary. Smectite (35-62 %), illite (28-51 %) and kaolinite (12-19 %) constitute the dominant clay minerals in the < 2 mu m fraction of the surface sediments. The patterns of clay mineral distribution suggest sediment transport from the Buyuk Menderes River and dispersal from the river to the outer continental shelf by the prevailing current regime. Downcore changes in the clay mineral assemblages (downward-decreasing smectite/iilite ratios) reflect changes in weathering conditions of the terrigenous source, from a colder climate during early Holocene to relatively warmer periods toward the present. Widely occurring partly metamorphosed volcanic rocks characterize the major geological sources of clay minerals on the adjacent hinterland. (c) 2007 Elsevier Ltd and INQUA. All rights reserved.