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Öğe A New Late Holocene Eolianite Record from Altinkum Beach, North Cyprus(Tubitak Scientific & Technological Research Council Turkey, 2012) Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Ertek, Topcu AhmetIn this study, we investigated the main depositional characteristics and obtained Optically Stimulated Luminescence (OSL) ages of coastal eolianite on the north coast of Cyprus, where this occurrence had not previously been recorded. Based on EDX/SEM and XRD data and field observations, the studied eolianite that crops out between elevations of 1 m and 14 m a.s.l. is made up predominantly of quartz grains, most of which consist of medium- to fine-grained sand. The rock comprises aragonite, calcite and quartz with lesser amounts of bornite and hematite as accessory minerals. OSL ages indicated that the initial deposition of eolianite sands took place at 1.51 +/- 0.21 ka years ago.Öğe Aeolian imprints of multiple Mediterranean invasions of the Black Sea during Pleistocene(Elsevier, 2022) Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Makaroglu, Ozlem; Bozcu, Mustafa; Ozturk, Muhammed Zeynel; Selim, Haluk Hamit; Nowacyzk, Norbert R.Climate changes determined the repeated connections between the Black Sea, Caspian Sea and Mediterranean Sea. The landlocked anoxic Black Sea basin was exposed to several transgressions throughout Quaternary by the Mediterranean Sea through the Straits of Istanbul (Bosphorus) and by the Caspian Sea through the Manych-Kerch spillway. Sedimentological records of these connections are limited mostly to the marine terrace deposits of Marine Isotope Stage (MIS) 5e while the pre-MIS 5e period remains uncertain due to a lack of robust facies and chronological data from deep-sea sedimentary sequences. Here we discuss the imprints of multiple Mediterranean transgressions during Middle Pleistocene in the Black Sea based on facies analysis and the optical age of coastal carbonate aeolianites. Contrary to today's hydro-climate of the Black Sea, the aeolianites bear witness to the transformation of the Black Sea into a warm inland sea during successive Mediterranean invasions. Prior to the onset of aeolian deposition, paleosols were formed on the Eocene-aged hardened sandy silts, suggesting strongly washed soil. This is evidenced by no calcium carbonate and a high Rb/Sr ratio, with quartz amounting to of 99.8%. According to our OSL ages, carbonates deposited on the shelf plain under higher temperature and increased evaporation conditions in MIS 15 and the later interglacial phases were transported to the coastal sand dunes during the transitional phases of MIS 15-14, MIS 13-12, MIS 11-10 and MIS 9-8. We suggest that the carbonate-rich and ooid-containing aeolianites were repeatedly formed in the multiple Mediterranean transgression stages, beginning with an increasingly severe dry phase following the Brunhes-Matuyama magnetic reversal.Öğe Age, composition and paleoenvironmental significance of a Late Pleistocene eolianite from the western Black Sea coast of Turkey(Pergamon-Elsevier Science Ltd, 2013) Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Ekinci, Yunus Levent; Demirci, Alper; Ertek, Ahmet; Canel, TimurOn the basis of field observations, thin section interpretations, microanalytical data, electrical resistivity survey and luminescence dating, the age, composition and internal structure of coastal eolianite on the west Black Sea coast at Sile, Istanbul, was studied for a combined interpretation of dune rock development and facies characteristics. Results demonstrate that the eolianite is made up of south-dipping, large-scale dune stratification, consisting mainly of quartz sand and, in particular, abundant ooids, as well as the binding cement which is composed of calcite and aragonite. Based on Electrical Resistivity Tomography (ERT) images, the eolianite has a thickness of between 3.5 m and 8 m and overlies a buried rugged topography that has developed on the Pliocene unit. This suggests the predominance of northerly winds that account for the landward removal of dune sands by offshore wind drift prior to carbonate cementation. Optically Stimulated Luminescence (OSL) dating estimations revealed that the initial deposition of the laminated eolianite layers on the underlying older unit took place at 138.57 +/- 13.65 ka, matching the Karangatian highstand or Marine Isotope Stage (MIS) 5e. (C) 2012 Elsevier Ltd and INQUA. All rights reserved.Öğe Analyses of Seismic Deformation at the Kibyra Roman Stadium, Southwest Turkey(Wiley, 2013) Karabacak, Volkan; Yonlu, Onder; Doku, Eray; Kiyak, Nafiye Gunec; Altunel, Erhan; Ozudogru, Sukru; Yalciner, Cahit CaglarThe ancient city of Kibyra in southwest Turkey has the potential to reveal the location and date of historical earthquakes. The most compelling evidence for earthquake faulting is observed in the city's Roman stadium. Damage related to seismic shaking is characterized by systematically collapsed columns, dilated and collapsed walls, and by rotated and displaced blocks in the stadium. Detailed archaeoseismological observations suggest that Kibyra was affected by earthquakes that were also recorded in historical earthquake catalogs. Although there is no historical record of a large earthquake after the 5th century A.D., Optically stimulated luminescence (OSL) dating of deposits under the collapsed blocks suggests a later seismic event. OSL results indicate that another large event occurred in southwest Turkey, probably around the 10-11th century A.D., and caused extensive damage (I-o = VIII-IX) to the Kibyra stadium.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; Yiğitbaş, ErdinçThis 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 Eolianite and coquinite as evidence of MIS 6 and 5, NW Black Sea coast, Turkey(Elsevier Sci Ltd, 2017) Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Selim, Hamit Haluk; Bozcu, Mustafa; Ozturk, Muhammed Zeynel; Ekinci, Yunus Levent; Demirci, AlperThis paper discusses the implications of a lowstand carbonate eolianite and overlying transgressive sequence of coquinite at Sile on the Turkish Black Sea coast based on composition, depositional characteristics and optical age estimations. The cross-bedded eolianite is a mixed ooid quartz grainstone in composition, yielding a depositional age matching MIS 6. It formed at the backshore of the paleobeach with the supply of sediment the from the beach face and offering insights into the drift of mixed shallow marine carbonates and siliciclastics together with radial ooids by onshore winds from a subaerially exposed high- to low-energy ooid shoals and oolitic sand complexes which developed parallel to the shoreline on the shallow shelf margin. During this lowstand, a low-relief dune retaining a record of opposing paleowind directions than that of prevalent northeasterly winds of today appears to have been lithified to form dune rock (aeolinite) under drier conditions compared to the present. Coinciding with MIS 5e, shallow marine coquina beds resting unconformably on the eolianite indicate the occurrence of the Mediterranean transgression during the last interglacial, as confirmed by benthic foraminifera within the high-salinity tolerant coquina shells. (C) 2017 Elsevier B.V. All rights reserved.Öğe Holocene Activity of Kutahya Fault Zone(Tmmob Jeoloji Muhendisleri Odasi, 2012) Altinok, Sevgi; Karabacak, Volkan; Yalciner, Cahit Caglar; Bilgen, A. Nejat; Altunel, Erhan; Kiyak, Nafiye GunecKutahya Basin which is located near the northeast boundary of the Western Anatolia Extension Region is a depression area that extends in WNW-ESE direction. Southern margin of the basin is bounded by a distinct fault morphology called Kutahya Fault Zone. Geological, geomorphological and geophysical studies on the Kutahya Fault Zone show that this zone consists of 5 different fault branches. Total length of the mapped fault zone is about 22 km in N50-70W direction. Paleoseismological and archeoseismological studies show that there are at least two surface rupturing earthquakes during the last 8000 years. First earthquake was occurred around 6000 BC and the last one was around 1800 B.C. after which the Seyitomer Tell was abandoned. Thus, this study indicates that the Kutahya Fault Zone has produced destructive earthquakes during Holocene and considering the length of the fault zone, it is possible to suggest that the fault zone has earthquake potential at least 6.5 magnitude.Öğe On the Origin and Age of the Ariburnu Beachrock, Gelibolu Peninsula, Turkey(Tubitak Scientific & Technological Research Council Turkey, 2008) Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Bozcu, Mustafa; Ertek, Ahmet; Gungunes, Hakan; Sungur, Ali; Turker, GulenThe beachrock formation on the Ariburnu coast situated in the Gelibolu Peninsula has been studied by field observation, thin-section interpretation, physicochemical analyses including ICP-AES and SEM/EDS, and OSL dating. These analyses reveal the presence of different amounts of major (Si, Ca, Mg, K, Fe, Al and Na) and trace elements within the beachrock cement with Si (36.2%) and Ca (32.68%) dominating the overall composition. Beachrocks composed of highly-fractured and friable beds reach a total thickness of 80 cm extending from + 60 cm at the uppermost level down to-1 m at their most seaward extent and grade from conglomerate to lithic arkose in vertical section. The total amount of CaCO3 ranges between 59.08% and 36% and the cement consists of high-Mg calcite based on EDS analysis. From SEM examination, four main morphologies were identified in cement material: (1) micritic coatings, (2) cryptocrystalline pore-filling cement, (3) meniscus cement and (4) microbial cement and suggest the presence of marine phreatic conditions with the exception of meniscus bridges, which imply that cementation may have been dominated by carbonate-rich meteoric waters at any successive stage of cementation. Five buried beachrock samples under unconsolidated beach sand were sampled for Optically Stimulated Luminescence (OSL) dating and show that the minimum and maximum ages of beachrock are 1.42 +/- 0.20 ka and 2.28 +/- 0.28 ka BP, respectively.Öğe Optical Stimulated Luminescence Dating Study of Eolianite on the Island of Bozcaada, Turkey: Preliminary Results(Coastal Education & Research Foundation, 2010) Kiyak, Nafiye Gunec; Erginal, Ahmet EvrenIn the present paper, eolianite exposed on the south coast of the semiarid island of Bozcaada, Turkey, was investigated on the basis of geomorphologic and petrographic data, and optically stimulated luminescence (OSL) dating results. The eolianite is lithic arenite in composition and contains abundant quartz, calcite, and various lithoclasts amalgamated with micritic calcite, sparitic calcite, and meniscus cements. Within the youngest layers standing at 1-2 m above sea level, the rock contains rhizoliths with or without carbonaceous fills. The OSL ages obtained ranged between 24.21 +/- 1.53 ka and 16.18 +/- 1.70 ka, suggesting that eolianite constitutes an example of low stand deposits coinciding with oxygen isotope stage 2 (OIS-2).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.
