Avrasya Yer Bilimleri Enstitüsü

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http://hdl.handle.net/11527/19784

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  • Öge
    IX. Türkiye Kuvaterner Sempozyumu, 20-23 Ekim 2020 İstanbul
    (İstanbul Teknik Üniversitesi, Avrasya Yer Bilimleri Enstitüsü, 2020-10) Yıldırım, Cengiz ; Duzman, Turgut ; Sağlam, Ezgi ; Bozyiğit, Ceren Naz ; Yılmazer, Sinan
    Türkiye’deki tek etkinlik olması nedeniyle büyük bir önem taşımaktadır. Tüm insanlığın geleceği içinde yaşadığımız gezegenimizin katmanları arasındaki etkileşimlerin daha iyi anlaşılmasına bağlıdır ve Kuvaterner Sempozyumu bu etkileşimin insan ile olan ilişkisinin ortaya konması açısından çok önemli bir görevi yerine getirmektedir.
  • Öge
    Active 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) Aykut, Tunahan ; Yıldırım, Cengiz ; Uysal, I. Tonguç ; orcid.org/0000-0003-0503-3859 ; orcid.org/0000-0001-5253-028X ; orcid.org/0000-0002-8263-8774 ; Katı Yer Bilimleri
    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
  • Öge
    The merit of the North Sea-Caspian pattern in explaining climate variability in the Euro-Mediterranean region
    (Wiley, 2023) Çağlar, Ferat ; Yetemen, Onur ; Chun, Kwok Pan ; Şen, Ömer Lütfi ; orcid.org/0000-0002-2584-2883 ; orcid.org/0000-0003-1593-3519 ; orcid.org/0000-0001-9873-6240 ; orcid.org/0000-0002-8186-8594 ; İklim ve Deniz Bilimleri
    Teleconnection patterns are one of the key features to understanding high-frequency natural climate variability. The North Sea-Caspian Pattern (NCP) was identified as a middle tropospheric dipole and its hydroclimatological implications have been substantially restricted to the Eastern Mediterranean region. Thus, the hydroclimatological influences of the NCP in the Euro-Mediterranean region were investigated via a comparative approach with dominant tropospheric teleconnections in the Eurasian region and synoptic features such as ridge-trough positioning and strength. By using high-resolution ERA5 reanalysis data, cross-correlations between indexes, anticorrelations at 500 hPa and composite anomaly maps for seasonally representative months were produced to understand the working mechanism of the NCP. Comparisons included the East Atlantic/Western Russian (EAWR) pattern, a rotated principal component analysis (RPCA) variant of NCP which utilizes pole-based representation. Analysis revealed that the NCP was correlated well with the Mediterranean trough displacement and with the strength of the East Asian trough. Climate anomalies indicated by the NCP were greater and more spatially consistent compared to other teleconnections. The NCP also showed higher contrasts of temperature and precipitation than the EAWR based on the composite anomaly maps. In conclusion, the NCP explained climate variability in all seasons linking remote centres of action within Eurasia's east and west extremes.
  • Öge
    Model-based prediction of water levels for the Great Lakes: a comparative analysis
    (Springer, 2024) Kurt, Onur ; 0000-0002-4486-2257 ; İklim ve Deniz Bilimleri
    This comprehensive study addresses the correlation between water levels and meteorological features, including air temperature, evaporation, and precipitation, to accurately predict water levels in lakes within the Great Lakes basin. Various models, namely multiple linear regression (MLR), nonlinear autoregressive network with exogenous inputs (NARX), Facebook Prophet (FB-Prophet), and long short-term memory (LSTM), are employed to enhance predictions of lake water levels. Results indicate that all models, except for FB-Prophet, perform well, particularly for Lakes Erie, Huron-Michigan, and Superior. However, MLR and LSTM show reduced performance for Lakes Ontario and St. Clair. NARX emerges as the top performer across all lakes, with Lakes Erie and Superior exhibiting the lowest error metrics—root mean square error (RMSE: 0.048 and 0.034), mean absolute error (MAE: 0.036 and 0.026), mean absolute percent error (MAPE: 0.021% and 0.014%), and alongside the highest R-squared value (R2: 0.977 and 0.968), respectively. Similarly, for Lake Huron-Michigan, NARX demonstrates exceptional predictive precision with an RMSE (0.029), MAE (0.022), MAPE (0.013%), and an outstanding R2 value of 0.995. Despite slightly higher error metrics, NARX consistently performs well for Lake Ontario. However, Lake St. Clair presents challenges for predictive performance across all models, with NARX maintaining relatively strong metrics with an RMSE (0.076), MAE (0.050), MAPE (0.029%), and R2 (0.953), reaffirming its position as the leading model for water level prediction in the Great Lakes basin. The findings of this study suggest that the NARX model accurately predicts water levels, providing insights for managing water resources in the Great Lakes region.
  • Öge
    Impact of atmospheric rivers on the winter snowpack in the headwaters of Euphrates-Tigris basin
    (Springer, 2024) Ezber, Yasemin ; Bozkurt , D. ; Şen, Ömer Lütfi ; 0000-0002-4512-685X ; 0000-0002-8186-8594 ; İklim ve Deniz Bilimleri
    Understanding the hydrometeorological impacts of atmospheric rivers (ARs) on mountain snowpack is crucial for water resources management in the snow-fed river basins such as the Euphrates-Tigris (ET). In this study, we investigate the contribution of wintertime (December-January–February) ARs to precipitation and snowpack in the headwater regions of the ET Basin for the period of 1979–2019 using a state-of-the-art AR catalog and ERA5 reanalysis data. The results show that AR days in the headwaters region could be warmer by up to 3 °C and wetter by over 5 mm day−1 compared to non-AR days. The contribution of ARs to the total winter precipitation varies from year to year, with a maximum contribution of over 80% in 2010 and an average contribution of 60% over the 40-year period. While snow accumulation on AR days shows spatial variability, the average snow contribution is 27% of the seasonal average, ranging from 12 to 57% for different years. The south-facing parts of the mountain range experience significant snowmelt, with contributions ranging from 15 to 80% for different years. The high total precipitation (60%) and low snowpack (27%) contribution can be attributed to the semi-arid characteristics of the region and the occurrence of rain-on-snow events, where rain falling on existing snow rapidly melts the snowpack. The findings have implications for water resource management and call for continued research to improve our knowledge of ARs and their interactions with the complex terrain of the ET Basin.
  • Öge
    A rare piedmont glaciation in the Mediterranean: insights from cosmogenic 36Cl dating of Davraz hummocky moraine field (SW Türkiye)
    (Wiley, 2024) Altınay, Onur ; Sarıkaya, Mehmet Akif ; Wilcken, Klaus M. ; orcid.org/0000-0003-1821-6814 ; Katı Yer Bilimleri
    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.
  • Öge
    Sedimentary 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) Sarı, Selma ; Mohammadi, Ali ; Schwamborn, Georg ; Haghipour, Negar ; Yong Yu, Byung ; Eriş, Kürşad Kadir ; Lak, Razyeh ; orcid.org/0000-0003-2400-8392 ; Katı Yer Bilimleri
    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.
  • Öge
    Latitude or altitude as the future refugium? A case for the future of forests in Asia Minor and its surroundings
    (Wiley, 2024) Ekberzade, Bikem ; Yetemen, Ömer ; Ezber, Yasemin ; Şen, Ömer Lütfi ; Dalfes, Hasan Nüzhet ; orcid.org/0000-0002-3271-2040 ; orcid.org/0000-0003-1593-3519 ; orcid.org/0000-0002-4512-685X ; orcid.org/0000-0002-8186-8594 ; orcid.org/0000-0002-2522-8381 ; İklim ve Deniz Bilimleri
    At the current juncture with climate change, centennial projections of species distributions in biodiversity hotspots, using dynamic vegetation models may provide vital insight into conservation efforts. This study aims to answer: (1) if climate change progresses under a business-as-usual scenario of anthropogenic emissions for this century, how may the forest ranges be affected? (2) will there be potential regional extinctions of the taxa simulated? (3) may any site emerge as a potential refugium? Study Area: Anatolian Peninsula and its surroundings, longitudes 24–50° E, latitudes 33–46° N. Time Period: 1961-2100. Major Taxa Studied: 25 woody species and a C3 grass-type. Method: Keeping a spatial window large enough to track potential changes in the vegetation range and composition especially in the mountain ranges within the study area, we parameterized a process-based regional-to-global dynamic vegetation model (LPJ-GUESS v 4.1), forced it with ERA5-Land reanalysis for the historical period, and five different bias-corrected centennial global circulation model (GCM) datasets under SSP5-8.5, and simulated the dynamic responses of key forest species. Bivariate spatio-temporal maps from the simulation results were constructed for final analysis. Results: A significant increase in woody taxa biomass for the majority of our study area, towards the end of the century was simulated, where temperate taxa with high tolerance for drought and a wider range of temperatures took dominance. The mountain ranges in our study area stood out as critical potential refugia for cold favoring species. There were no regional extinctions of taxa, however, important changes in areal dominance and potential future forest composition were simulated. Main Conclusions: Our simulation results suggest a high potential for future forest cover in our study region by the end of the century under a high emissions scenario, sans human presence, with important changes in vegetation composition, including encroachment of grasslands ecosystems by woody taxa.
  • Öge
    Exploring pre-neolithic environmental dynamics : paleoecology around the Göbekli Tepe based on a multiproxy approach in southeastern Türkiye
    (Springer, 2024) Biltekin, Demet ; Güzel, Abdülkadir ; Özcanlı, Mehmet ; Gökgöz, Dila Doğa ; Akbıyık, Mehmet ; 0000-0003-2976-0321 ; 0000-0002-4168-4803 ; 0000-0002-1017-4122 ; 0000-0002-5139-8384 ; Ekoloji ve Evrim Anabilim Dalı
    Background and aims Paleoecological findings from soil samples recovered near the Göbekli Tepe indicate an environment that sustains a variety of multiproxy analyses, revealing prominent changes in ecological conditions. Methods Soil samples were collected in the vicinity of the pre-Neolithic site in the Göbekli Tepe. These sediment samples underwent comprehensive analysis utilizing a multiproxy approach, which included pollen analysis, total organic carbon (TOC) and total inorganic carbon (TOC) measurements, and X-ray fluorescence (XRF) elemental analysis. Results Total organic carbon varied significantly in the SK-1 section, with lower levels at the bottom and higher levels at the top. The Ca/Ti ratio, which is indicative of weathering and moisture availability, typically increased in the early Holocene and briefly decreased at approximately 13,354 years BP. The Sr/Ti ratio, related to weathering and erosion processes, also suggests intensified weathering. The presence of deciduous forests and the increase in organic carbon values further support the notion of favorable environmental conditions during the early Holocene. In contrast, the lower levels of SK-1 show lower organic carbon values, lower Ca/Ti and Sr/Ti ratios, and greater abundances of herbaceous plants and steppes, indicating colder and drier conditions at 13,354 years BP. Conclusion A significant increase in organic carbon values and the presence of deciduous Quercus in the upper levels of the SK-3 section suggest a period of increased organic productivity and the existence of deciduous forests during the early Holocene at the Göbekli Tepe.
  • Öge
    8 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) Görüm, Tolga ; Yılmaz, Abdüssamet ; Tanyaş,, Hakan ; Akgün,, Aykut ; Akbaş, Abdullah ; Karabacak, Furkan ; Çoşkun, Suat ; Uçar, Tuğçe ; Fidan, Seçkin ; Kılıcaslan, Hakan ; Tatar, Orhan ; Katı Yer Bilimleri
    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.