GM8.2

New insights into Southern Caucasian glacial-interglacial climate conditions inferred from Quaternary gastropod faunas

Dr. Christiane Richter¹, Dr. Daniel Wolf¹, Dipl.-Biol. Frank Walther², Dr. Stefan Meng³, Dr. Lilit Sahakyan^4, M. Sc. Tilmann Wolpert⁵, Prof. Dr. Markus Fuchs⁵, Prof. Dr. Michael Zech¹, Prof. Dr. Dominik Faust¹

¹Dresden University of Technology, Helmholtzstr. 10, 01069 Dresden, Germany

² University Hamburg, Centrum für Naturkunde, Martin-Luther-Platz 3, 20146 Hamburg, Germany

³ Ernst-Moritz-Arndt-University Greifswald, Friedrich-Ludwig-Jahn-Str. 17a, 17489 Greifswald, Germany

⁴ National Academy of Sciences of the Republic of Armenia, Baghramyan Ave. 24a, 0019 Yerevan,
  Armenia

⁵ Justus-Liebig-University Giessen, Senckenbergstr. 1, 35390 Gießen, Germany

We present our latest results  from gastropod analyses conducted on loess palaeosol sequences from northeast Armenia (Southern Caucasia) covering at least three glacial-interglacial cycles. The ecostratigraphy shows significant patterns of species composition related to the succession of pedocomplexes and loess, respectively. Pedocomplexes included species that can be associated with highgrass- to forest-steppe biomes, indicating increased humidity for these sections compared to loess layers. In contrast, loess layers that relate to glacial periods are associated with gastropod species of semidesert environments with shrub- and shortgrass-steppes, indicating semiarid to arid conditions. Furthermore, the loess deposits do not show any evidence for cold-adapted gastropod species. Therefore we suggest that average July temperatures in the study area were above 10°C, even during periods of loess deposition. We propose, that the limiting factor for bios during glacial periods was aridity, rather than temperature. In addition, we observe environmental differences between the various glacial times, with our results indicating a trend towards steadily increasing aridity in Southern Caucasia across the Middle to Late Pleistocene.

How to cite: Richter, C.: New insights into Southern Caucasian glacial-interglacial climate conditions inferred from Quaternary gastropod faunas, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5284, https://doi.org/10.5194/egusphere-egu21-5284, 2021.

Dunefield margins are prone to changing domination between aeolian and fluvial systems. Dominating aeolian systems divert or block fluvial systems or/and reduce their erosional forces often leading to amplified sedimentation by a wide range of unique aeolian-fluvial (A-F) sediments. Other arid environments are mainly dominated by eroding ephemeral fluvial systems that usually characterized by sediment degradation.

The late Pleistocene encroachment of vegetated linear dunes into the northwestern Negev desert dunefield  (Israel) comprised a distinct period of aeolian domination upon ephemeral drainage systems originating in the loess-clad Central Negev highlands. This study analyzes the sediments, geomorphology and landscape evolution caused by A-F processes along dunefield margins, in particular sediments deposited by dune-dammed water bodies slightly upstream of the dunefield edge and between VLDs, using high-resolution field mapping, relative (portable) and absolute OSL dating, stratigraphy and sedimentological analyses. These sediments have been generally mapped as playa sediments, understood to be deposited in a fluvial-dominated environment.

Six main A-F sediment types were identified and interpreted: (a) Aeolian sand appears to be remnants of fluvial eroded VLD.  (b) Fluvial sand originates from dune erosion and deposited nearby. (c) Massive loam to silty-clay loam relates to abrupt changes in the hydraulic parameters (width/depth ratio and water losses through infiltration) which induce sudden change in flow velocity, resulting in unsorted massive deposits of upstream loess and other desert soil bedload. (d) Couplets, similar to the massive loam, contains loess and upstream sediments deposited in a standing water body. (e) Laminated silty-clay-loam units were identified only between VLDs. (f) High-energy fluvial deposits, which contain loam, sand and pebbles, with  a clear erosional boundary that mark the upstream edge of A-F sedimentation.

The landscape of the Negev dunefield margins developed since the late Pleistocene by short-term aeolian domination, which gradually changed into fluvial domination during the Holocene. Dune-damming depositions occurred during this transition. First outside the dunefield, then propagated downstream into the dunefield. Fluvial aggradation of A-F sediments resulted in a vast playa-like flats, that following dune-dam breaching underwent incision, let alone in small (~<20 km²) basins.

How to cite: Robins, L., Roskin, J., Yu, L., and Greenbaum, N.: Aeolian-fluvial sediments and landscapes along the northwestern Negev Dunefield (Israel) margins since the late Pleistocene, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3262, https://doi.org/10.5194/egusphere-egu21-3262, 2021.

Fluvial sediments are valuable paleoenvironmental archives of the Quaternary. Since besides environmental factors they are also affected by local tectonics or intrinsic processes, large instead of small catchments should be studied. In drylands covering ca. 45% of the global terrestrial surface large river systems are generally missing, and most river systems are small rivers originating from mountain ranges. Their sediments are potentially interesting paleoenvironmental archives, but are often affected by intensive tectonics. During this study, to obtain a robust regional paleoenvironmental signal a small river system in the southwestern Binaloud Mountains in semi-arid NE Iran was exemplarily studied with a combined approach that encompassed both alluvial fan and catchment. By using geomorphological mapping and numerical dating, fluvial aggradation followed by incision was independently identified in larger areas or in different parts of the river system ca. 95–88 ka, 40 ka, 20 ka, around/after the Pleistocene/Holocene transition and possibly ca. 2.6 ka. These could be linked with regional and over-regional paleoenvironmental data. Furthermore, large boulders on the alluvial fan suggest anthropogenic destabilisation of the catchment during the last decades. Despite strong local tectonics the fluvial dynamics was mostly controlled by paleoenvironmental changes and human activity. This indicates that despite their small size, such river systems form valuable paleoenvironmental archives in drylands where other archive types are largely missing. 

How to cite: Khosravichenar, A., Fattahi, M., Amini, H., and von Suchodoletz, H.: The potential of small mountain river systems for paleoenvironmental reconstructions in drylands - An example from the Binaloud Mountains in northeastern Iran, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3438, https://doi.org/10.5194/egusphere-egu21-3438, 2021.

The alluvial/fluvial fan systems of northern Oman act as sensitive geoproxy records of Late Quaternary palaeohydrology and past landscape evolution, offering records of palaeoenvironmental change which cannot be reconstructed from nearby speleothem records alone (Parton et al., 2013). These systems also provide evidence for the important link between the changing abundance of freshwater in the Arabian interior and the dispersal of anatomically modern humans (AMHs) out of Africa (Rosenberg et al., 2012). Limited previous luminescence dating analyses have reported fan activation west of the Hajar during insolation maxima and monsoon intensification throughout the Late Quaternary (Parton et al., 2015). However, there are currently no studies to date which present chronologies for the fan systems to the east of the Hajar Mountains.

We present the first luminescence based chronology for the fan systems to the east of the Hajar Mountains, providing landform scale data on fan behaviour, including spatial-temporal complexity and variability. This facilitates comparison of the temporal response of fans east and west of the mountains, including differential responses to external forcing. Ages will also be compared with regional palaeoenvironmental and palaeoclimatic records, to inform landscape reconstructions in northern Oman during the late Quaternary.

References

Rosenberg, T.M., Preusser, F., Blechschmidt, I., Fleitmann, D., Jagher, R. and Matter, A., 2012. Late Pleistocene palaeolake in the interior of Oman: a potential key area for the dispersal of anatomically modern humans out‐of‐Africa?. Journal of Quaternary Science, 27(1), pp.13-16.

Parton, A., Farrant, A.R., Leng, M.J., Schwenninger, J.L., Rose, J.I., Uerpmann, H.P. and Parker, A.G., 2013. An early MIS 3 pluvial phase in Southeast Arabia: climatic and archaeological implications. Quaternary International, 300, pp.62-74.

Parton, A., Farrant, A.R., Leng, M.J., Telfer, M.W., Groucutt, H.S., Petraglia, M.D. and Parker, A.G., 2015. Alluvial fan records from southeast Arabia reveal multiple windows for human dispersal. Geology, 43(4), pp.295-298.

How to cite: Woor, S., Durcan, J., Parton, A., and Thomas, D.: Luminescence dating Hajar Mountain alluvial fan systems, northern Oman, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2325, https://doi.org/10.5194/egusphere-egu21-2325, 2021.

The Seymareh landslide is the largest rock slope failure (44 Gm³) ever recorded on the exposed Earth surface. It detached ∼10 ka BP from the northeastern flank of the Kabir-Kuh anticline (Zagros Mts., Iran) originating the natural dam responsible for the formation of a three-lake system (Seymareh, Jaidar, and Balmak lakes, with an area of 259, 46, and 5 km², respectively). The lake system persisted for ∼3000 yr during the Holocene before its emptying phase due to overflow. A sedimentation rate of 21 mm yr⁻¹ was estimated for the Seymareh lacustrine deposits, which increased during the early stage of lake emptying because of enhanced sediment yield from the lake tributaries. 

To reconstruct the climatic and environmental impact on the lake infilling, we reviewed the geomorphology of the basins and combined the results with multi-proxy records from a 30 m thick lacustrine sequence in Seymareh Lake. Major analyses comprise grain size analysis, carbon and oxygen stable isotopes of carbonate-bearing sediments, and X-ray diffraction analysis of clay minerals.

Lake overflowing is largely accepted as the main response to variations in water discharge and sediment supply since the alternation from dry to wet phases enhances sediment mobilization along hillslopes decreasing the accommodation space in the downstream sedimentary basins. In this regard, during the early-middle Holocene, the Seymareh area, as well as the entire Middle East, was affected by short-term climate changes at the millennial-scale, as testified by both paleoecological and archaeological evidence. Indeed, several records from Iranian lakes (i.e., Mirabad, Zeribar, Urmia) well documented the temperature and the moisture conditions of the western Zagros Mountains during the Holocene. During the early Holocene, the precipitation remained low up to 6 ka BP, reaching the driest condition around 8-8.2 ka BP. The impact of this abrupt climate change is evident across West Asia, where the first large villages with domesticated cereals and sheeps disappeared, converting to small hamlets and starting habitat-tracking. As regards the Seymareh area, a more irregular distribution of rainfalls and their increasing seasonality may support rhexistasy conditions, during which the scarce vegetation cover enhances both the hillslope erosion and sedimentation rate in the basins, most likely contributing to the overflow of Seymareh Lake. 

How to cite: Delchiaro, M., Iacobucci, G., Troiani, F., Della Seta, M., Ballato, P., and Aldega, L.: Middle Holocene environmental reconstruction and climatic inferences through multi-proxy records from Seymareh lake sediments (Zagros Mts., Iran), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12511, https://doi.org/10.5194/egusphere-egu21-12511, 2021.

Our understanding of climate changes throughout the Holocene is hampered by representativeness in sedimentary archives. Potential production and preservation biases of the markers are identified by comparing these proxies with modern environments. It is important to conduct robust calibrations on each biome. These calibrations use large database dominated by forest samples. The Mongolian plateau is especially characterized by low annual precipitation and continental annual air temperature. The characterization of the climate system of this area is crucial for the understanding of Holocene Monsoon Oscillations. This study focuses on the calibration of proxy-climate relationships for pollen and glycerol dialkyl glycerol tetraethers (GDGTs) by comparing large published Eurasian calibrations with a set of 49 new surface samples (moss polster, soil and mud from temporary dry pond). These calibrations are then cross-validated by an independent dataset of top-core samples and applied to two Late Holocene paleosequences in the Altai mountains and the Qaidam basin. We show that: (1) preserved pollen assemblages are clearly imprinted on the extremities of the ecosystem range but mitigated and unclear on the ecotones; (2) for both proxies, inferred relationships depend on the geographical range covered by the calibration database as well as on the nature of samples; (3) even if local calibrations suffer from reduced amplitude of climatic parameter due to local homogeneity, they better reflect actual climate than the global ones by reducing the limits for saturation impact, (4) a bias in climatic reconstructions is induced by the over-parameterization of the models and (5) paleoclimate values reconstructed here are consistent with Mongolia-China Late Holocene climate trends, and validate the application of local calibrations for both pollen and GDGTs. We encourage the application of this surface calibration method to reconstruct paleoclimate and especially consolidate our understanding of the Holocene climate and environment variations in Arid Central Asia.

How to cite: Dugerdil, L., Joannin, S., Peyron, O., Jouffroy-Bapicot, I., Vannière, B., Bazartseren, B., Unkelbach, J., Behling, H., and Ménot, G.: Mongolian dryland paleoenvironment and paleoclimate issues : calibrations and applicability of GDGT and pollen reconstructions over the Late Holocene., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3390, https://doi.org/10.5194/egusphere-egu21-3390, 2021.

Little is known about the tufa deposits within the volcanic Harrats of western Saudi Arabia. This research aims to characterise the fossil tufa system and examine its utility as a palaeoenvironmental archive. This requires us to understand the conditions under which the tufa was deposited. In particular, to ascertain whether they are cool, freshwater tufa, or geothermal travertine. In this presentation we show the extent of the tufa within the basin, describe the stratigraphy and settings, as well as their composition and petrology, alongside U-Th chronological control for a selection of suitable subsamples

The samples are composed of low-Mg calcium-carbonate and their ⁸⁷Sr/⁸⁶Sr composition shows there has been water-rock interaction with the mafic metavolcanic Neoproterzoic bedrock as well as metamorphosed marine carbonates from the Arabian Escarpment at the head of the Wadi Dabsa catchment. Their δ¹³C composition (-6.3 to -12.9 ‰) is indicative of a meteoric water and soil signature, rather than a geothermal source.

The tufa deposits are widespread within the Wadi Dabsa Basin, with at least three phases of deposition, recorded at the basin surface, within incised wadi channels and in a downstream fan region. In some locations, the size of tufa-cemented fluvial bedload represents very high magnitude events, whilst the lacustrine to paludal facies indicate more quiescent phases of increased moisture availability. The U-Th dating indicates that the basin was wet during interglacial stages (Marine Oxygen Isotope Stags [MIS] 7 and 5) with some indication, given the error ranges on dates from multiple-subsamples, that deposition occurred primarily during interstadials (e.g. MIS 5e, 5c and 5a). The MIS 7 age is from a vug-fill tufa deposits within an extensive tufa cascade, which indicates the cascade itself pre-dates MIS 7.

The major concentration of artefacts (> 3000) in this basin make it one of the richest Palaeolithic assemblages so far recorded in southwest Saudi Arabia (Foulds et al., 2015; Inglis et al., 2019). This site is ~ 6 km from the current coastline, which is inland from the MIS 5e shorelines in this region (Inglis, pers comm), and these sites with freshwater mean it is important to continue to consider coastal sites as corridors with habitable landscapes for hominins.

References

Foulds, F., A. Shuttleworth, A. Sinclair, A. M. Alsharekh, S. Al Ghamdi, R. H. Inglis, G.N. Bailey (2017) A large handaxe from Wadi Dabsa and early hominin adaptations within the Arabian Peninsula. Antiquity. 91:1421–1434.

Inglis, R. H., Fanning, P. C., Stone, A., Barford, D. N., Sinclair, A., Hsing-Chung, C., Alsharekh, A., Bailey, G. (2019). Palaeolithic artefact deposits at Wadi Dabsa, Saudi Arabia: A multi-scalar geoarchaeological approach to building an interpretive framework.  Geoarchaeology 34(3), 272-294.   

How to cite: Stone, A., Sahy, D., Inglis, R., Candy, I., Alsharekh, A., and Sinclair, A.: Former humid phases in the southwestern Arabian peninsula: climatic and environmental implications of the tufa record over the last 250 ka from the Harrat Al Birk, Saudi Arabia. , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16409, https://doi.org/10.5194/egusphere-egu21-16409, 2021.

Desert research has a bold track record in deciphering the evolution of landforms. While iconic objects such as inselbergs, yardangs, wadis or dune fields have attracted the attention of scientists for decades and inspired them to develop numerous formation concepts, it is the actual processes, which are suggested to govern their formation, that are usually quite hard to survey as they happen in nature. This amiguitity is due to the often unpredictable, event based, rapid yet episodic nature of their occurrence. While dedicated devices for measuring these processes inevitably exist, they are either confronted with a small spatial footprint (point measurement) or temporal discontinuousity (time lapse data), or even both of these drawbacks. As a consequence, important processes like flash floods, bedload agitation, mass movement on hillslopes, thermal weathering, dune migration rate and mechanism, or averaged information about ground moisture change, substrate rheology, and temperature diffusion can be studied as they happen under natural conditions only in exceptional cases.

Here I summarise recent developments from the field of environmental seismology, an emerging discipline that studies the seismic signals emitted by Earth surface processes, with a focus on existing and potential applications to desert environments. I present seismic approaches to detecting, tracking and quantifying flash floods and the sediment they convey, provide an overview of the capabilites of seismology to survey hillslope activity at the catchment scale, and discuss the potential to monitor surface and subsurface activity at the plot scale. The overarching aim of the contribution is to foster a discussion about potential research questions that could be tackled in future joint (i.e., established and seismic sensor) instrumentation projects.

How to cite: Dietze, M.: Listen to a spectre – the potential role of environmental seismology in desert process research, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3350, https://doi.org/10.5194/egusphere-egu21-3350, 2021.

Badland areas are present in all continents, excluding Antarctica, and play a critical role in establishing local erosion and sedimentation rates. The presence of unconsolidated rocks (e.g., marls, sandstone, mudstone etc.) is a major driver controlling the distribution of badlands, which together with other environmental components, such as climate, tectonics, vegetation, and topography, determine their forms and processes. The mutual interaction of controlling factors in badlands areas provides a basis for developing a holistic approach to clarify their distribution patterns. Turkey's geodynamic evolution has led to the emergence of marine sedimentary rocks, pyroclastics, and continental clastics, especially in line with the uplift of the Anatolian Plateau and volcanism during the last 8 Ma.

This study aims to explore the country-scale distribution of badlands and the controlling factors of this badland distribution in Turkey. Remarkably wide badlands landscapes (4494 km²) have been visually inspected using Google Earth Pro^TM to further digitize and extract geomorphological units by applying high-resolution multispectral images provided by WorldView-4/Maxar Technology and CNES/Airbus. To obtain exact boundaries, we eliminated contiguous flat areas surrounding the identified badlands by using red relief image map (RRIM) mosaics that express surface concavity and convexity combined with topographic slope derived from a digital elevation model of 5-m spatial resolution. Last, to determine the controlling factors of badlands distribution, we have compiled a global data set comprising 1-km resolution layers of mean annual precipitation, temperature and precipitation seasonality, aridity, NDVI, rainfall erosivity factor, elevation, and majority values of regional lithology in sub-catchments units. The enhanced investigation of the complex relationship that expresses the controlling factors of badlands distribution, has been conducted by K-means unsupervised cluster analysis.

Our comprehensive regional analyses exploring the distribution and environmental attributes of major Turkish badlands identified five different groups or clusters of badlands that display spatial coherence with climatic and tectonic settings. We argue that Turkey's climatic and topographic transition zones, varying from Mediterranean climate dominated areas to the more arid Central Anatolian Plateau, and tectonically‑induced topographic barriers play a relevant role in discriminating these groups of badlands. Moreover, the Anatolian diversity of sedimentary rocks, which consists of Neogene and Paleogene continental clastics, volcano clastics & pyroclastics, and lacustrine deposits, makes an essential contribution to the identified, extensive badland distribution.

This study has been produced benefiting from the 2232 International Fellowship for Outstanding Researchers Program of the Scientific and Technological Research Council of Turkey (TUBITAK) through grant 118C329. The financial support received from TUBITAK does not mean that the content of the publication is approved in a scientific sense by TUBITAK.

How to cite: Avcioglu, A., Gorum, T., Akbas, A., Moreno de las Heras, M., and Yetemen, O.: The climatic, topographic and litho-tectonic characteristics of badlands in Turkey, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7788, https://doi.org/10.5194/egusphere-egu21-7788, 2021.