Forty-four boulders from moraines in two glacial valleys of Mount Erciyes (38.53°N, 35.45°E, 3917m), central Turkey, dated with cosmogenic chlorine-36 (36Cl), indicate four periods of glacial ...activity in the past 22ka (1ka=1000 calendar years). Last Glacial Maximum (LGM) glaciers were the most extensive, reaching 6km in length and descending to an altitude of 2150m above sea level. These glaciers started retreating 21.3±0.9ka (1σ) ago. They readvanced and retreated by 14.6±1.2ka ago (Lateglacial), and again by 9.3±0.5ka ago (Early Holocene). The latest advance took place 3.8±0.4ka ago (Late Holocene). Using glacier modeling together with paleoclimate proxy data from the region, we reconstructed the paleoclimate at these four discrete times. The results show that LGM climate was 8–11°C colder than today and moisture levels were somewhat similar to modern values, with a range between 20% more and 25% less than today. The analysis of Lateglacial advance suggests that the climate was colder by 4.5–6.4°C based on up to 1.5 times wetter conditions. The Early Holocene was 2.1–4.9°C colder and up to twice as wet as today, while the Late Holocene was 2.4–3°C colder and its precipitation amounts approached to similar conditions as today. Our paleoclimate reconstructions show a general trend of warming for the last 22ka, and an increase of moisture until Early Holocene, and a decrease after that time. The recent glacier terminates at 3450m on the northwest side of the mountain. It is a remnant from the last advance (possibly during the Little Ice Age). Repeated measurements of glacier length between 1902 and 2008 reveal a retreat rate of 4.2m per year, which corresponds to a warming rate of 0.9–1.2°C per century.
We report the presence of Late Pleistocene piedmont glaciers represented by the largest hummocky moraine field observed in the Eastern Mediterranean. The piedmont glaciers originated from the ...Geyikdağ ice cap (∼40 km2), situated between 2350 and 2650 m above sea level (a.s.l.) (Central Tauride Mountains of Turkey), and deeply carved the north-facing hillslopes before reaching the Namaras Valley (2000–2050m a.s.l). The hummocky moraines resulted from in-situ deposition of stagnant glacier ice where debris cover was heterogeneously distributed on the glacier surface. Thirty-four boulders from hummocky, disintegration, lateral and terminal moraines from the Namaras Valley and the tributary Susam Valley (2100–2200 m a.s.l.) were dated by cosmogenic 36Cl surface exposure dating. The moraine ages indicate three phases of deglaciation during the Late Pleistocene. The oldest deglaciation occurred in the Namaras Valley at 18.0 ± 1.1 ka (ka: thousand years ago) towards the end of the Last Glacial Maximum (LGM) and is recorded entirely by hummocky moraines. We speculate that hummocky moraine forming processes with cycles of relief inversion gave rise to boulder apparent ages up to a few thousand years younger in our study area. Therefore, 18.0 ± 1.1 ka should be regarded as a minimum age with a probable true age much closer to the local-LGM values (∼20 ka) as observed in the surrounding mountains. Paleo-piedmont glaciers also deposited several lateral moraines that are ∼50 m higher than the hummocky moraines. Although the lateral moraines probably represent the build-up and the hummocky moraines the final phase of the same local-LGM-pulse, both lateral moraines started to retreat from the Late-glacial (14.0 ± 2.7 ka) and gradually disappeared by mid-Holocene (5.2 ± 1.0 ka), encompassing the Younger Dryas (YD) stadial. In the Susam Valley, the Late-glacial is represented by a terminal moraine (13.4 ± 1.5 ka). The glacier retreat was very fast as indicated by an almost instantaneous disappearance of 5 km long Susam Valley glacier, represented by disintegration and hummocky moraines (14.0 ± 1.3 ka). Alternatively, in case the oldest boulder age is taken into account, the Susam Valley glacier can be also attributed to the late LGM (∼17 ka) to Late-glacial (∼14 ka) transition. Near the exit of the Susam Valley a right lateral moraine was deposited 11.6 ± 1.3 ka ago, confirming the presence of the YD in Geyikdağ. Comparable glacial chronologies were obtained from other Turkish and Mediterranean mountains.
•Mid-latitude piedmont glaciers deposited hummocky moraines in Taurus Mountains.•Thirty-four samples were dated by cosmogenic 36Cl nuclides.•Hummocky moraines settled by 18.0 ± 1.1 ka ago from stagnant glacier ice.•Lateglacial moraines were deposited between 17.6 ± 2.9 ka and 14.0 ± 2.7 ka ago.•A Younger Dryas lateral moraine was dated to 11.6 ± 1.3 ka in Susam Valley.
Mount Geyikdağ in the Taurus Mountain Range in southern Turkey was glaciated during the Late Pleistocene. Several glacial and periglacial landforms such as moraines and rock glaciers are present in ...Mount Geyikdağ. Here we described two geomorphic units, a well-preserved moraine loop (so called Zor Moraine) and a rock glacier inside that loop, which have contrasting morpho-stratigraphic positions and terrestrial cosmogenic nuclide (TCN) 36Cl inventories. We measured 4 samples from each landform. The boulders of Zor Moraine have ages that range from 3.7 ± 0.3 ka to 7.8 ± 0.6 ka with a weighted average age of 5.5 ± 1.2 ka. This age agrees well with the Mid-Holocene glaciation observed within the same range. On the contrary, the boulders of the rock glacier have much older ages. They are in between 9.7 ± 0.9 ka and 14.2 ± 1.1 ka with a weighted average age of 12.5 ± 1.3 ka. We attribute this unlikely situation to excessive inheritance within the rock glacier boulders. On the contrary, Zor Moraine boulders contain no to negligible amount of inheritance, as glacial carving is a very efficient mechanism in removing pre-exposure component. Our study indicates that caution should be taken into account when interpreting the apparent age of a landform as boulders from different landforms might have considerably different prior exposure histories even within a closely related glacial/periglacial environment. It is possible that rock glacier boulder TCN results can yield seemingly maximum ages related to pre-exposure problems. Therefore an independent verification of rock glaciers’ age by other dating methods is advised.
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•A moraine loop and a rock glacier situated inside that loop have contrasting TCN ages.•A young looking rock glacier have old TCN ages attributed to inheritance.•Inheritance is not a problem in TCN dating of moraine boulders.•Inheritance is a major limiting factor in TCN dating of rock glacier boulders.
For the first time in Turkey, we report an early advance of glaciers before the broadly defined global Last Glacial Maximum (LGM). Forty-one moraine boulders from three glacial valleys on Mount Akdağ ...(36.54°N, 29.57°E, 3016 m), southwest coast of Turkey, were dated with cosmogenic 36Cl. Valleys on the north side of the mountain were filled with few km long glaciers that terminated at elevations of about 2000 m above sea level (a.s.l). The pre-LGM glaciations reached their maximum positions (2150 m a.s.l) by 35.1 ± 2.5 ka ago (1σ; ka = 1000 calendar years). The glaciers readvanced during the global LGM and reached their farthest locations (2050 m a.s.l) by around 21.7 ± 1.2 ka ago. Later, glaciers retreated and shortly stabilized during the Lateglacial at around 15.1 ± 0.9 ka ago. Using the glacier modeling and paleoclimate proxies from the Eastern Mediterranean, we estimated that if temperatures during the LGM were 8–11 °C colder than modern, which is suggested by paleotemperature proxies from the region, precipitation was up to two times more than that of today. Previous estimates on southwest coast of Turkey indicate a similar precipitation value while central Turkey requires drier conditions, implying regional heterogeneity on LGM climates in Turkey.
•Pre-LGM glaciers started to retreat by 35.1 ± 2.5 ka ago.•LGM glaciers were active until 21.7 ± 1.2 ka ago.•Lateglacial moraines were deposited 15.1 ± 0.9 ka ago.•LGM climate was 8–11 °C colder, and twice as wet as today.
Cappadocia, in the Central Anatolian Plateau of Turkey, is famous for its unique landscape and unusual rock formations. The development of this landscape dates back to Late Miocene epoch (c. ...10millionyears) when volcanoes spread pyroclastic deposits over an area of about 20,000km2. The volcanism continued for several millions of years and laid down thick and colorful ignimbrite layers. The evolution of the Cappadocian landscape starts with nearly-horizontal plateaus, which are then dissected, usually along cooling fractures, to form mushroom-like structures (hoodoos) locally known as “fairy chimneys”. Different layers of ignimbrites have different resistance to erosion: softer layers (necks) are easier to erode compared to the harder ignimbrites (caps). When the chimneys are isolated, the caps play an important role in slowing further erosion of softer layers. When the caps finally drop or completely erode away, the soft necks of the chimneys are quickly destroyed. Here, for the first time, we have determined the bedrock erosion rates at the three evolution stages of fairy chimneys using the cosmogenic chlorine-36 (36Cl): the pre-chimney (plateaus) stage, the chimney stage and the post-chimney stage. The data show that the plateaus erode at a very low rate between 0.58±0.02cm/ky and 0.93±0.05cm/ky. When dissection of a plateau starts, the erosion rate increases to about 4.5±0.6cm/ky. The caps of chimneys have erosion rates between 3.21±0.36cm/ky and 3.39±0.36cm/ky. Once the chimneys disappear, erosion rates increase significantly to 28.0±9.9cm/ky.
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•Bedrock erosion rates of Cappadocia ignimbrites were calculated by in-situ 36Cl.•3 stages of fairy chimney evolution were sampled; plateau, chimney, post-chimney.•Plateaus erode at a low rate between 0.58 and 0.93cm/ky.•Caps of fairy chimneys have erosion rates of 3.21 to 3.39cm/ky.•Once the chimneys disappear, erosion rates increase to 28.0±9.9cm/ky.
Investigating Quaternary glaciations by terrestrial cosmogenic nuclide dating provides unique insights into glacial landscapes. However, postglacial processes may reshape these topographies via ...weathering, erosion and deposition, especially after the glaciers have entirely disappeared. Understanding the timing of Quaternary glaciations in the areas developed under different geomorphological processes may be challenging. In this study, we produced a detailed geomorphological map of Mt. Barla in the Western Taurus Mountains of Turkey. We found that geomorphological processes such as karstification and mass movements provided favourable settings for the valleys to be carved by glaciers during the Late Pleistocene. We applied in-situ cosmogenic 36Cl surface exposure dating to moraine boulders to reveal the glacial chronology and the geomorphological evolution. We dated moraine boulders (n = 11) from two glacial valleys that show at least two and possibly three deglaciations during the Late Pleistocene. For Gedik Valley, the left lateral moraine marks the Late-glacial glacier retreat by 16.6 ± 2.6 ka (MIS 2). On the other hand, the terminal moraine indicates that the most extensive glaciation occurred at 42.1 ± 5.2 ka (pre-global LGM) in this valley. The outer terminal moraine age (45.5 ± 6.8 ka) in Kapıdere Valley confirms this MIS 3 extension. Our results also imply even a possible earlier glaciation in Kapıdere Valley at 78.5 ± 17.6 ka (MIS 5), even though more data are needed to confirm this extent.
•Non-glacial surface processes provided the basis for glacier formations in Mt. Barla.•Multiple glacier advances occurred during the Late Pleistocene.•Using 36Cl cosmogenic exposure dating, we report the oldest glacial event in Turkey.•Lateral moraines imply glaciation during MIS 5 (78.5 ± 17.6 ka).•Lateral moraines indicate final deglaciation during MIS 2 (16.6 ± 2.6 ka).
Evidence of widespread alpine glaciations during the Late Pleistocene in mid-latitudes has long attracted attention of researchers. However, there were no studies that contain absolute ages in the ...Lesser Caucasus despite the fact that it is one of the major glaciated regions in Eurasia. Here, we present first cosmogenic 36Cl surface exposure ages from the Karçal Mountains (41.24° N, 42.06° E, 3431 m a.s.l., above sea level) which is located in the most western part of the Lesser Caucasus in the northeastern Anatolia. In the Karçal Mountains, there are numerous valleys that have experienced significant glaciations since Late Pleistocene. We have investigated one of the largest valleys, the east-facing Karçal Valley, that hosts even a small (2926 m a.s.l.) recent glacier located at above 3000 m a.s.l. Fossil and recent rock glaciers along with lateral and recessional moraines exist in the valley. We conducted the study in two stages. First, we mapped the geomorphological units in the Karçal Valley in detail based on our field works and aerial photography. Later, we collected 10 rock samples from the fossil rock glacier and recessional moraines for cosmogenic 36Cl surface exposure dating. The results outline a glacial chronology that is typical of the Last Glacial Maximum. Although the maximum extent and timing of the glaciation is not exactly known as lateral and terminal moraines were not suitable for sampling, recessional moraines indicate that the Karçal Valley palaeoglacier deglaciation started at least 19.9 ± 1.2 ka ago. Fossil rock glacier samples were dated to 15.7 ± 1.3 ka. These quantitative results are first in the Lesser Caucasus and compatible with previous ages obtained from other valleys in the nearby Eastern Black Sea region, Anatolian and some of the European Mountains.
•First numerical age data from Lesser Caucasus in NE Turkey.•Ten samples were dated by cosmogenic 36Cl nuclides.•Recessional moraines were deposited 19.9 ± 1.2 ka ago after the Last Glacial Maximum.•Maximum age of the fossil rock glacier is 15.7 ± 1.3 ka.
The Namaras rock avalanche (NRA) deposit originated from the northern flank of the glaciokarstic Geyikdağ Mountain in the Central Taurus Range, SW Turkey. The deposit has an area of ~0.430 km2 and an ...estimated average thickness of 10 m, corresponding to 4.3 million m3 volume. The fan-shaped deposit area consists of house-sized Jurassic-Cretaceous neritic limestone boulders that overlie lateral and hummocky moraines down into the valley. We used geomorphological mapping and 36Cl surface exposure dating to obtain six boulder ages which unravelled the NRA age, the number of events and their geometric features. Our results indicate that the NRA consists of two successive mid-to-late Holocene events; the first high magnitude main event with a weighted average age of 4.59 ± 0.25 ka followed by a second low magnitude event with a weighted average age of 3.77 ± 0.20 ka. 36Cl exposure dating of the lateral moraine covered by the rock avalanche deposit yielded approximately an age of ~12.30 ± 1.20 ka. The older event with a maximum runout distance of 1550 m and 600 m elevation loss yielded in a travel angle of 21°. Similarly, the younger event with 1720 m maximum runout length and 640 m vertical elevation loss resulted in a travel angle of 20°. The bedded limestone with cross-joints in the glacial cirque preconditioned the NRA slope failure. The significant lag time between deglaciation and the rock avalanche indicates that the glacial erosion and debuttressing acted as preparatory factors. Based on the low seismic activity in the Central Taurus Range and the synchronicity of the rock avalanche with mid-to-late Holocene climatic transitions, we propose that climatic factors may have triggered the NRA failure. The age of the older main event coincides with the warm drought period of the mid-Holocene associated with torrential rainfalls in the Taurus Mountains, while the age of the younger event correlates with the long wet period in the late Holocene. Thus, the main NRA event may have been triggered by the influence of warm temperatures and intense rainfall, while the second event may have been triggered by prolonged period of high precipitation. The two events of the NRA are coeval with the enhanced rock slope failures dating back to 5–3 ka in the Alps.
•A rock avalanche with two successive events in the SW Turkey was mapped and dated.•First event: high magnitude, with 0.415 km2 area and 4.59 ± 0.25 ka age•Second event: low magnitude, with 0.127 km2 area and 3.77 ± 0.20 ka age•The glacial erosion appears as the preparatory factor of the rock avalanche.•The mid-Holocene climatic variabilities possibly triggered the rock avalanche.
Here we documented the vertical displacement, slip rate, extension rate, and geochronology of normal faults within a narrow strip along the main strand of the Ecemiş Fault Zone. The Kartal, Cevizlik, ...and Lorut Faults are normal faults that have evident surface expression within the strip. Terrestrial cosmogenic nuclide geochronology revealed that the Kartal Fault deformed the 104.2 ± 16.5 ka aged alluvial fan surface and the Cevizlik Fault deformed the 21.9 ± 1.8 ka old moraine and talus fan surfaces. Our topographic surveys indicated 120 ± 10 m and 13.1 ± 1.4 m surface‐breaking vertical displacements along the Kartal and Cevizlik Faults, respectively. Accordingly, we suggest a 1.15 ± 0.21 mm a−1 slip rate and 0.66 ± 0.12 mm a−1 extension rate for the last 104.2 ± 16.5 ka on the Kartal Fault, and a 0.60 ± 0.08 mm a−1 slip rate and 0.35 ± 0.05 mm a−1 extension rate for the last 21.9 ± 1.8 ka on the Cevizlik Fault. We believe that these structures are an integral part of intraplate crustal deformation in the Central Anatolia. They imply that intraplate structures such as the Ecemiş Fault Zone may change their mode through time; presently, the Ecemiş Fault Zone has been deformed predominantly by normal faults. The presence of steep preserved fault scarps along the Kartal, Cevizlik, and Lorut Faults point to surface‐breaking normal faulting away from the main strand and particularly signify that these structures need to be taken into account for regional seismic hazard assessments.
Key Points
Cosmogenic dating of geomorphic features
Slip rate and extension rate of normal faults
Quaternary deformation in the Ecemiş Fault Zone
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