4 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 4 / 4
Yayın Akdağ Kütlesi’nde (Batı Toroslar) Pleistosen buzullaşmalarının jeomorfolojik özellikleri ve optik uyarmalı lüminesans (OSL) ile yaşlandırılması(Türk Coğrafya Kurumu, 2017) Bayrakdar, Cihan; Güneç Kıyak, Nafiye; Turoğlu, Hüseyin; Öztürk, Tuğba; Canel, TimurBatı Torosların en yüksek ikinci zirvesine (Uyluk T. 3014 m) sahip olan Akdağ, batıda Eşen Ovası (60 m) doğuda Elmalı Ovası (1100 m) arasında yer alan ve 2700 m üzerinde birçok zirve barındıran, çevresine göre oldukça yüksek bir kütle görünümündedir. Akdağ Kütlesi'nde Kuvaterner'de meydana gelen buzul şekillerini incelemek ve OSL ile tarihlendirmek çalışmanın temel amacıdır. Bu çalışmada coğrafi bilgi sistemleri ve morfometrik analizler, OSL tarihlendirme yöntemi ve sedimantolojik analizlerden faydalanılmıştır. Akdağ Kütlesi'nin jeomorfolojik gelişiminde birden fazla etken ve sürecin rolü olmuştur. Bu süreçlerin başında karst, buzul, tektonik ve flüviyal gelmektedir. Akdağ Kütlesi'nde etkili olan Pleistosen buzullaşmaları, büyük ölçüde karstik yapıya uyumlu gelişmiş ve 2500 m ve üzerindeki paleo-karstik depresyonlarda kalın plato buzulları oluşmuştur. Akdağ Kütlesi'nde üçü büyük, beş buzul vadisi tespit edilmiştir. Bu buzul vadileri gelişmiş sirklerle başlayıp 2500 m seviyelerinde paleokarstik depresyonlara uyumlu olarak düşük eğimli, geniştabanlı ve büyük ölçüde taban ve yanal morenleri ile kaplı iken 2500 m seviyelerinden sonra vadiler daralıp klasik tekne vadi formu alıp 2000 m seviyelerinde cephe morenleri ile sonlanırlar. Akdağ Kütlesi'nde morenlerden alınan örneklere ait OSL tarihlendirmelerinde 17-21 bin yaşları çıkmıştır ki bu da son buzul dönemi MIS 2 ye denk gelmektedir.Yayın Records of repeated drought stages during the Holocene, Lake Iznik (Turkey) with reference to beachrock(Pergamon-Elsevier Science Ltd., 2016-07-15) Öztürk, Muhammed Zeynel; Erginal, Ahmet Evren; Güneç Kıyak, Nafiye; Demirci, Alper; Ekinci, Yunus Levent; Cürebal, İsa; Avcıoğlu, Mustafa; Öztürk, TuğbaThe 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).Yayın Quaternary rock uplift rates and their implications for the western flank of the North Anatolian Fault restraining bend; inferences from fluvial terrace ages(Blackwell Publishing Ltd, 2020-10-01) McClain, Kevin P.; Yıldırım, Cengiz; Ciner, Attila; Şahin, Sefa; Sarıkaya, Mehmet Akif; Özcan, Orkan; Güneç Kıyak, Nafiye; Öztürk, TuğbaIn the western flank of the North Anatolian Fault restraining bend (i.e., Central Pontides), the Filyos River incises through the uplifting Karabük Range, creating the ~1.7-km-deep Filyos River Gorge on the hanging wall of the reverse Karabük Fault. Seven fluvial strath terrace levels are preserved in this gorge. optically stimulated luminescence ages from quartz-rich sediments of five terrace levels reveal an average long-term rock uplift rate of 0.45 ± 0.02 mm yr?1 with an unsteady pattern of uplift during the last 542 ± 24 kyr. Uplift rates of 1.52 ± 0.6 and 0.74 ± 0.3 mm yr?1 occurred before 366 ± 19 kyr, followed by lower rates of ~0.1 and 0.31 mm yr?1 through present. These later uplift rates may reflect relatively slower tectonic rates since ~366 kyr, with closer similarity to regional uplift rates of ~0.3 mm yr?1 yielded from the eastern flank of the Central Pontides. The Karabük Range fluvial terraces are near the North Anatolian Fault, meaning pre- ~366 kyr uplift rates may be a glimpse of the highest Central Pontides Quaternary rock uplift rates on uplifting hanging wall blocks activated by the restraining bend. When we consider offshore seismic reflection data, the focal mechanism solution of the Bartın Earthquake, onshore structural data, and regional tectonic geomorphology, the western flank of the Central Anatolian Plateau's northern margin is propagating northward as a growing orogenic wedge with a positive flower-structure geometry.Yayın River, alluvial fan and landslide interactions in a tributary junction setting: Implications for tectonic controls on Quaternary fluvial landscape development (Central Anatolian Plateau northern margin, Turkey)(Elsevier B.V., 2021-03-01) McClain, Kevin P.; Yıldırım, Cengiz; Çiner, Tahsin Attila; Sarıkaya, M. Akif; Özcan, Orkan; Görüm, Tolga; Köse, Oğuzhan; Şahin, Sefa; Güneç Kıyak, Nafiye; Öztürk, TuğbaAlong the western flank of the northern margin (Central Pontides) of the Central Anatolian Plateau, the humidity from the Black Sea is much higher than the central and eastern flanks and creates a complex relationship between surface and tectonic processes by triggering intense mass wasting activity and aggradation within narrow valleys. We identified three incised fill terrace levels and used Optically Stimulated Luminescence (OSL) dating to calculate fluvial sediment ages and cosmogenic 36Cl exposure dating to calculate limestone boulders exposure ages across the terrace surface. Stratigraphical interpretations and OSL ages of the lowest levels revealed that a fluvial fill terrace formed in the main valley at 275.6 ± 12.8 ka and was overlain by a main river-tributary junction alluvial fan that was abandoned at 39.5 ± 3.5 ka. The results collectively show the influence of climate, topography, hillslope processes, and lithology on aggradation-incision patterns of main rivers. Prolonged aggradation can prevent the channel equilibrium required to calculate rock uplift rates while also causing a new base-level and aggradation upstream. This effect can be exacerbated in uplifting mountainous regions with limited depositional areas. Bedrock incision rates based on the fluvial terrace age were between 0.15 and 0.2 mm/a since 39.5 ± 3.5 ka. However, the high aggradation within this segment of the main valley prevented incision of the channel bedrock for long periods, causing a potential underestimation of the rock uplift rate calculation. Our local period of aggradation appears to be related to increased aggradation and decreased bedrock incision rates measured 14 km upstream that were previously assumed to be the result of decreased tectonic uplift rates. This demonstrates the importance of corroborating strath terrace incision rate estimations with ages and incision rates of downstream fill terraces, if present, to check for potential interference with the tectonic signal.
