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Öğe A Preliminary Note on Depositional Characteristics and Optical Luminescence Age of a Marine Terrace, Strait of Canakkale, Turkey(Coastal Education & Research Foundation, 2013) Avcioglu, Mustafa; Erginal, Ahmet Evren; Kiyak, Nafiye Gunee; Kapan-Yesilyurt, Sevinc; Yigitbas, ErdincAvcioglu, M.; Erginal, A.E.; Kiyak, N.G.; Kapan-Yesilyurt, S., and Yigitbas. 2013. A preliminary note on depositional characteristics and optical luminescence age of a marine terrace, Strait of Canakkale, Turkey, Journal of Coastal Research, 29(1), 225-230. Coconut Creek (Florida), ISSN 0749-0208. This preliminary study investigated the depositional features and optical luminescence age of marine terrace sediments located on the east coast of the Strait of Canakkale, Turkey. With regard to depositional setting, the studied sequence is formed mostly of shallow marine deposits rich in quartz and oysters as well as other accessory minerals and various fossil sea shells. In vertical section, the sequence is characterized by two different stratigraphic units, i.e. a 1.50-m-thick sandy to gravely bottom unit (unit A) and an overlying 2.5-m-thick fossiliferous zone (unit B). On the basis of optically stimulated luminescence (OSL) age estimations obtained from six sampling levels from bottom to top, we determined superimposed cycles of deposition during interglacials from 246.47 +/- 25.32 ka (unit A) at MIS 7 to 127.48 +/- 8.91 ka (unit B) at MIS 5.Öğe Beachrock formation on the coast of Gokceada Island and its relation to the active tectonics of the region, northern Aegean Sea, Turkey(Pergamon-Elsevier Science Ltd, 2016) Avcioglu, Mustafa; Yigitbas, Erdinc; Erginal, Ahmet EvrenThere are beachrock formations in 5 different sections of the south coast of Gokceada, Turkey's largest Aegean island. These beachrocks form two different groups in terms of layering characteristics, delta O-18 and delta C-13 stable isotope compositions, consecutive cementation structures, and C-14 dating. The West Group beachrocks, to the west, were dated to 4010-5830 BP, while the East Group beachrocks were dated to 620-2390 BP. The beachrock formations in both groups are separated by the NE-SW-trending Ugurlu Fault. The Ugurlu Fault is a right lateral, strike slip with reverse component oblique fault, and is an active fault within the North Anatolian Fault Zone. In the period between the formation of the two beachrock groups (2390-4010 BP), an earthquake was responsible for the destruction of Gokceada Yenibademli mound and the development of two generations of beachrock. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.Öğe Cementation characteristics and age of beachrocks in a fresh-water environment, Lake Iznik, NW Turkey(Elsevier, 2012) Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Ozturk, Muhammed Zeynel; Avcioglu, Mustafa; Bozcu, Mustafa; Yigitbas, ErdincThis paper focuses on the cement characteristics and optical luminescence age of late Pleistocene-Holocene beachrock, exposed on the southeast shore of freshwater Lake Iznik in northwest Turkey, based on field observations, various spectroscopic analyses and optical dating results. The studied beachrock is a poorly-sorted coastal conglomerate composed mostly of gravels derived from surrounding volcanic rocks and marbles as well as quartz and carbonate grains. We identified different types of cements; dominated by micritic envelopes, bladed isopachous aragonite rims, void fills, radial aggregates and meniscus bridges, implying no single origin. Cementation characteristics indicate that marine-like cement micro-fabrics may occur in freshwater lake environments where the lake-water chemistry favors carbonate precipitation. OSL data revealed the existence of older beachrock dating back to 20.2 ka, together with younger Holocene-age beachrock of between 5.6 and 2.4 ka. This suggests that younger beachrocks have been superimposed on older cemented carbonates through the removal of carbonates by wave motion (splash and spray) during lower lake level conditions. (C) 2011 Elsevier B.V. All rights reserved.Öğe Depositional Characteristics of Carbonate-Cemented Fossil Eolian Sand Dunes: Bozcaada Island, Turkey(Coastal Education & Research Foundation, 2013) Erginal, Ahmet Evren; Ekinci, Yunus Levent; Demirci, Alper; Avcioglu, Mustafa; Ozturk, Muhammed Zeynel; Turkes, Murat; Yigitbas, ErdincErginal, A.E.; Ekinci, Y.L.; Demirci, A.; Avcioglu, M.; Ozturk, M.Z.; Turkes M., and Yigitbas, E., 2013. Depositional characteristics of carbonate-cemented fossil eolian sand dunes: Bozcaada Island, Turkey. Journal of Coastal Research, 29(1), 78-85. Coconut Creek (Florida), ISSN 0749-0208. Coastal eolianite on the south coast of Bozcaada Island, Turkey, was investigated by field observations, petrographic and climatological examinations, and electrical resistivity tomography data. The 4- to 7-m-thick eolianite, including rhizolith morphotypes characterized by root tubules and bifurcated root casts, demonstrates dune-sand accumulation during the Upper Pleistocene. Our results showed that paleowind drift and recent windblown sand drift on the island are similar. The dune sands exhibit various cement types formed of calcite and aragonite, such as micrite encrustations, meniscus and gravitational cements, and in particular, void fills. Dune-sand accumulation took place on the truncated surface of Miocene deposits. Geophysical data showed the existence of large weathered cavities within the eolianite and a high-angle normal fault, which displaces the eolianite, together with the underlying Miocene unit.Öğe First note on marine-like cementation of Late Holocene beachrock, Iznik Lake (Turkey)(Versita, 2012) Erginal, Ahmet E.; Kiyak, Nafiye G.; Ozturk, Muhammed Z.; Yigitbas, Erdinc; Bozcu, Mustafa; Avcioglu, Mustafa; Ozturk, BeyhanMicro-fabric characteristics and optically stimulated luminescence (OSL) dating results are presented to discuss the controlling agents and timing of beachrock cementation on the fresh-water Iznik Lake shoreline. The beachrocks are made up of grain-supported polygenic conglomerate containing 20.42% carbonate with encrusted grains, basically as micrite coatings, isopachous aragonite rims, cryptocrystalline void fills and meniscus bridges. The optical ages of twelve samples yielded ages that range from 4.226 +/- 0.569 ka on the lowermost beds to 0.706 +/- 0.081 on the uppermost. This is the first report of precipitation of marine-like cements in Iznik Lake. The abundant aragonite-dominated cement is likely indicative of precipitation-prone dry evaporative conditions from the climatic optimum to the last millennia.Öğe First record of beachrock on Black Sea coast of Turkey: Implications for Late Holocene sea-level fluctuations(Elsevier, 2013) Erginal, Ahmet Evren; Ekinci, Yunus Levent; Demirci, Alper; Bozcu, Mustafa; Ozturk, Muhammed Zeynel; Avcioglu, Mustafa; Oztura, ErdalWe present new data on the diagenetic characteristics, subsurface nature and radiocarbon ages of beachrock from the Thracian Black Sea coast of Turkey, indicative of sea-level changes and climatic conditions favoring lithification of beach sands between 5.4 ka and 3.5 ka cal BP. Micrite coatings and succeeding meniscus cements typify diagenetic history and suggest a two-stage cementation over this timeframe. The early cements are typical of upper intertidal zone when the sea-level was likely similar to that of today. The ensuing intergranular bridges refer to an approximate 2 m decline in sea-level, favoring downward percolation of meteoric waters related to subaerial exposure, marked by a reduction in Mg concentration and dissolution pits on early cement coatings. Formation of beachrock during this bimillennial period could be associated with relatively drier conditions promoting the precipitation of connective cements. (C) 2013 Elsevier B.V. All rights reserved.Öğe Geochemical and Mineralogical Analyses of Basalt Fragments from the Neolithic Settlement of Sumaki Höyük (Batman, Turkey) to Determine the Source Area(Tmmob Jeoloji Muhendisleri Odasi, 2023) Sarialtun, Savas; Aydin, Mahmut; Avcioglu, MustafaThis study aims to determine the provenance of grinding stone tools unearthed from the Neolithic phases of Sumaki Hoyuk settlement using a portable Energy Dispersive X-ray Fluorescence Spectrometer (P-EDXRF) and X-ray Diffraction spectrometer (XRD). Sumaki Hoyuk is located in the Lower Garzan Basin of Batman province, Turkey. The settlement is dated to 9084 +/- 57 -8123 +/- 50 cal BP. Grinding stone tools in this settlement are usually made of basalt. Albeit at low amounts, limestone was also used in the production of grinding stones. The Lower Garzan Basin, located to the east of Diyarbakir Basin, is surrounded by Mount Kiradagi to the west-southwest and Mount Raman to the south, the Garzan Anticlinal and Kentalan Anticlinal to the north-northeast. The basalt flow occurred in the Quaternary period. Samples collected from different parts of the Neolithic phase of Sumaki Hoyuk and the Kiradagi basalt flows were analysed using P-EDXRF to determine their chemical composition. The same samples were also analysed using XRD to determine their mineral composition. P-EDXRF and XRD analyses reveal that the samples from Sumaki Hoyuk and Kiradagi are in good accordance with each other. It is therefore understood that the basalt stone tools used in the settlement were taken from the Kiradagi basalts.Öğe Records of repeated drought stages during the Holocene, Lake Iznik (Turkey) with reference to beachrock(Pergamon-Elsevier Science Ltd, 2016) Ozturk, Muhammed Zeynel; Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Demirci, Alper; Ekinci, Yunus Levent; Curebal, Isa; Avcioglu, MustafaThe cement fabrics, subsurface nature and optically stimulated luminescence age of beachrocks along the shores of Lake Iznik in NW Turkey were studied within the context of Holocene lake level changes. With a maximum thickness of 1.5 m, the low-angle (average 5-10 degrees) beds are composed of coarse grains and small gravels and extend up to 5 m offshore at their most lakeward extremities. Cement textures on and around the poorly-rounded grains are made up of micrite envelopes and meniscus bridges as well as acicular aragonite rims. Geoelectrical resistivity sections taken from a representative location along the beach where the beds have maximum thickness showed that the sand-buried beds are followed up to about 24 m landward. Based on the OSL ages of 33 samples, the cemented beds occurred at four drier periods of the following: Pre- and Early Holocene (dated to 15-9 ka), Holocene Climatic Optimum (7.9-5.6 ka), Middle Holocene (4.9 ka-2.8 ka) and Late Holocene (2.0 ka-0.9 ka). (C) 2015 Elsevier Ltd and INQUA. All rights reserved.
