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Öge8 Aralık 2024 Güngören, Arhavi (Artvin) moloz çığının oluşum dinamiği ve alanın heyelan tehlike ve risk bakımından değerlendirmesi : bilimsel-teknik rapor, 10 Ocak 2025 | no. 2025/01(İTÜ Yayınevi, 2025)08 Aralık 2024 tarihinde, yaklaşık olarak saat 03.05’te, Sakarya’nın Karasu ilçesinden başlayan D010 (E70) Karadeniz Sahil Yolunun 1.167. kilometresinde gerçekleşen moloz çığı (ing. debris avalanche) dört vatandaşımızın ölümüne neden olmuştur. Moloz çığı, Artvin ilinin Arhavi ilçesine bağlı Güngören Mahallesi’nin en batısında, 287 m yüksekliğindeki bir yamaçtan eğim yönünde hareket ederek alt kotlarda kıyı şeridini de içine alacak şekilde gelişmiştir. D010 (E70) yolunun her iki yönünü de trafiğe kapatan moloz çığı tipindeki kütle hareketi, yapılan arama çalışmaları sonrasında yaklaşık olarak 21.00’da kontrollü bir şekilde tek yönlü olarak trafiğe açılmıştır. Maden Tetkik ve Arama Genel Müdürlüğü (MTA) ve Afet ve Acil Durum Yönetimi Başkanlığı (AFAD) ekiplerinin koordinasyonu ile olayda yaşamını yitirmiş dört vatandaşımızın içinde bulunduğu araç, İnsansız Hava Aracı (İHA) sistemine entegre manyetometre aracılığıyla tespit edilerek arama çalışmaları sonlandırılmıştır. 09-10 Aralık 2024 tarihleri arasında gerçekleştirdiğimiz saha çalışmaları sonrasında derlenen veriler, ölçümler ve arazi gözlemlerine dayalı olarak gerçekleştirdiğimiz bu değerlendirmede, moloz çığının oluşumu, jeolojik ve jeomorfolojik özellikleri, InSAR temelli mevcut ve önceki deformasyonların varlığı ve karakterizasyonu ile tetikleyici mekanizma ve olay sonrasındaki olası tehlike ve riskler ele alınmıştır.
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ÖgeActive deformation pattern in the western flank of the central Taurides, southern margin of the central Anatolian plateau: inferences from geomorphic markers and kinematic indicators(Wiley, 2023)The southwestern margin of the Central Anatolian Plateau corresponds to the upper crust of the subduction between African and Anatolian plates, with a high relief of up to 2 km. This mountainous region has distinctive geomorphological features and presents a unique setting to investigate the mechanism of orogenic plateau margin development related to subduction and topographic evolution around the Eastern Mediterranean. We present new kinematic data from exposed fault planes and tectonic landforms from high-resolution digital elevation models to elucidate the deformation pattern and its relation with the crustal deformation. We evaluate the deformation pattern based on the spatial distribution of kinematic analyses and geomorphic markers like low relief upland surfaces, disrupted karst basins, knickpoints, and deep bedrock incisions from watershed to shoreline. Our geomorphic analysis reveals a post-orogenic transient actively deforming topography. The geomorphic markers constrain long-term surface uplift pattern with a mean cumulative surface uplift of 1,710 ± 50 m and shows an increasing trend from west to east, from 1,600 ± 50 to 1,800 ± 50 m. Our results suggest a dome-like uplift pattern in the west-east direction across the southern margin that reaches up to maximum cumulative uplift values in the quadrangle of Alanya-Başyayla-Ermenek-Gazipaşa. Our kinematic measurements along the youngest generation of faults revealed an active NE-SW extensional deformation across a broad 200 km zone in the north of the subduction. Our findings have significant implications for understanding the morphotectonic evolution and post-orogenic deformation in the plateau margins and geodynamic evolution of the Eastern Mediterranean. Key Points River longitudinal profiles and low-relief upland surfaces indicated an increasing vertical deformation toward the eastern Central Taurides Geomorphic markers constrained mean cumulative 1,710 ± 50 m surface uplift that peaks in the quadrangle of Alanya-Başyayla-Ermenek-Gazipaşa Kinematic indicators from the youngest brittle structures revealed an active NE-SW extension above the Cyprus Subduction Zone
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ÖgeSedimentary evolution and lake level fluctuations of Urmia Lake (north-west Iran) over the past 50 000 years; insights from Artemia faecal pellet records(Wiley, 2024)A 25 m long sediment core from hypersaline Urmia Lake (north-west Iran) was studied for the Late Quaternary depositional history and palaeoclimate variations using the abundance and compositional characteristics of Artemia faecal pellets. Sediment analysis is supported by scanning electron microscopy – energy dispersive X-ray spectroscopy, organic and inorganic carbon content measurements, and stable isotopes (δ13C and δ18O) from faecal pellet carbonates. The imprecise chronology of the core back to 50 kyr bp is supported by ten radiocarbon ages from faecal pellets and bulk sediments. The palaeoenvironmental record is subdivided into four periods: (i) During much of Marine Isotope Stage 3, a period of lake level lowering is characterized by a decreasing amount of faecal pellets, and an increasing amount of coated grains, sulphate minerals and reworked shell fragments. (ii) During late Marine Isotope Stage 3 and early Marine Isotope Stage 2 a lake level lowstand and a lake floor exposure is interpreted based on the relatively low abundance of pellets, which are multicoloured and appear together with volcanic lithics and rounded sulphate minerals. (iii) During late Marine Isotope Stage 2 the record is devoid of pellets but dominated by large sulphate crystals suggesting a prolonged low lake level. (iv) During Marine Isotope Stage 1 a relative lake level highstand is rapidly established with sediments that are highly abundant in fresh pellets. The modern lake level lowstand is represented by a salt crust. The δ13C and δ18O records measured from faecal pellet carbonates suggest a link with the precipitation versus evaporation balance in the lake over time. From bottom to top the linear trend towards more negative delta values illustrates the increasing amount of precipitation arriving at the lake from the Late Pleistocene to the Holocene. Two prominent isotope minima during the Late Pleistocene and one prominent minimum in the early Holocene mark relative high lake levels, which can also be linked to Lake Van in Turkey.
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ÖgeA rare piedmont glaciation in the Mediterranean: insights from cosmogenic 36Cl dating of Davraz hummocky moraine field (SW Türkiye)(Wiley, 2024)Piedmont glaciers (lobes), typically found in high latitudes and large mountainous regions, extend from ice sheets and ice caps to lower altitudes. However, they can also occur, although less commonly, on mid-latitude mountains. When these fan-like glaciers retreat, they leave behind hummocky moraines scattered in a chaotic pattern. In this study, we have mapped one of these mid-latitude sites and established a Terrestrial cosmogenic nuclide (TCN) glacial chronology on Mount Davraz, namely Davraz hummocky moraine field (37°46′00″N, 30°43′15″E). Our findings indicate that the glaciers in this area started receding from the early local Last Glacial Maximum (LGM) period (21.8 ± 2.4 ka) to the early Late-glacial period (17.7 ± 2.2 ka), and eventually disappearing. The deglaciation of the Mt. Davraz palaeoglacier matches nearby mountains, supported by southerly winds as significant for regional glaciation. Our discoveries reveal a robust connection between southerly winds and nearby glaciation, contributing to our understanding of how climate influences glaciers. Likewise, the glacial timelines of the neighbouring mountains align with the glacial history of Mt. Davraz.