PICO
This session aims to pool contributions dealing with past to recent geomorphological processes and environmental changes spanning the entire Quaternary until today, as well as with all types of sedimentary and morphological archives in dryland areas (dunes, loess, slope deposits, fluvial sediments, alluvial fans, lake and playa sediments, desert pavements, soils, palaeosols etc.) studied on different spatial and temporal scales. Besides case studies on archives and landscapes from individual regions and review studies, cross-disciplinary, methodical and conceptual contributions are especially welcome in this session, e.g., dealing with the special role of aeolian, fluvial, gravitational and biological processes in dryland environments and their preservation in deposits and landforms, the role of such processes for past and present societies, methods to obtain chronological frameworks and process rates, and emerging geo-technologies.
PICO: Tue, 5 May, 08:30–10:15 | PICO spot 3
On the eastern Canary Islands, several valleys exist that were dammed later on by volcanic activity. Since that damming, these valleys (locally called “vegas”) have acted as sediment traps. The deposited materials include volcanic material, redeposited (soil-)sediments from the surrounding slopes, and dust originating from the northern African continent. Due to intense postsedimentary calcification processes Vega sections are typically characterised by an alternation of pale-coloured, carbonate-enriched layers (PCL) and reddish, clay-enriched layers (RCL), forming recurring sedimentary sequences.
This study shall contribute to the reconstruction of palaeoenvironmental conditions during the formation of vega sections on Lanzarote, with particular emphasis on aeolian dust deposits. Therefore, we combine grain-size analyses, geochemical (XRF) and mineralogical analyses (XRD), and luminescence dating (IRSL) with a principal component analysis (PCA) to evaluate geochemical fingerprints and compositional end-members.
Four distinct clusters have been identified reflecting different sediment sources and transport pathways. A first cluster is characterised by increased Si, Zr, quartz and plagioclase contents and has been interpreted as short range (silt-dominated) aeolian dust input. A second cluster shows high Al, K and kaolinite loadings and indicates long range (fine-grained) aeolian dust derived from more southerly regions of northern Africa. A third cluster is defined by elevated Fe, Ni and Zn concentrations, which are typical for basaltic source rocks on the eastern Canary Islands and reflect locally derived material. In contrast, Rb–V–enriched samples define a distinct trend, as Rb substitutes for K in fine-grained mineral phases and V is associated with Fe-(hydr-)oxides, pointing to a fine-grained sediment component differentiated from the Ni–Zn–rich basaltic signal and possibly reflecting an additional aeolian contribution. The fourth cluster is associated with Ti and Cr, elements occurring both in Saharan dust and in local basaltic volcanics; however, the presence of K-feldspar suggests a predominantly allochthonous contribution.
The cyclic pattern (alternating PCLs and RCLs) within vega sections highlights the sensitivity of these archives to changing environmental conditions. While variations in grain size, mineralogical composition, and geochemical signatures indicate shifting potential source areas and pathways of dust, the carbonate redistribution in combination with the characteristics of clay-dominated sediment layers reflect changing hydrological and hence palaeoclimatic conditions on the Eastern Canary Islands. Finally, we hope to contribute on the one hand to the understanding of Late Quaternary conditions in an over regional scale and on the other hand to the individual behaviour of the different subterritories.
How to cite: Labahn, J., Roettig, C.-B., Kolb, T., Schleicher, A.-M., Günter, C., Marburg, C., and Faust, D.: Potential dust source areas of Quaternary vega sediments on Lanzarote (Canary Islands), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20574, https://doi.org/10.5194/egusphere-egu26-20574, 2026.
Loess and other Late Quaternary palaeoclimate archives in Pakistan are not documented adequately yet and their extent and composition remain unclear, with only a few isolated occurrences being described. This highlights a major gap in systematic research to comprehend the ecological and palaeoclimate dynamics critical for the evolution of dryland and sedimentary records in this region. In this context the present investigation focuses on the presence and composition of silty Quaternary sediments. These have been suggested to be of aeolian and fluvial origin.
In this contribution, we summarize literature, and present observations from a recent field excursion supplemented by magnetic susceptibility data. We consider both aeolian loess and redeposited loess-like fluviolacustrine sediments to be present in much larger areas than earlier reports. Magnetic susceptibility properties are typical for in-situ sol formation, suggesting phases of landscape stability over at least centuries. We find that an aeolian sediment flux into the landscape was repeatedly intercalated by fluviolacustrine sediments of similar silt grain size. The aeolian sedimentation proceeded into mountain regions north of the Peshwar Basin, but in-situ preservation of fine material in sparse. At several places, loess is intercalated with (unrounded) slope deposits and fluvial deposits.
We conclude that Quaternary sedimentation in northern Pakistan is complex, and that landscape stability phases with soil formation occurred. Next steps will be to assess the stratigraphic and spatial (in) homogeneity of deposits, and to provide a temporal frame for soil formation phases.
How to cite: Zeeden, C., Murad, W., Mehmood Abbasi, A., Tsukamoto, S., and Ulfers, A.: Loess in northern Pakistan? Current Understanding, Knowledge Gaps, and New Field Observations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7772, https://doi.org/10.5194/egusphere-egu26-7772, 2026.
Global climate oscillations may strongly modify continental precipitation patterns. Understanding the history of these is thus, relevant for comprehending effects of past and ongoing climate change. For this purpose, precipitation estimates in a high spatio-temporal resolution are extremely useful and may be derived from geophysical properties of former land-surfaces such as fossil soils and sediments, if reliable climofunctions are available. Recently, promising transfer functions have been provided by linear regression analyses between geophysical topsoil properties (magnetic and colorimetric) across the Bačka Loess Plateau (Serbia) along a narrow precipitation gradient (MAP: 525±1 mm/a to 584±1 mm/a) and available meteorological data. Whilst these climofunctions need to be expanded regarding the calibrated precipitation range and tested considering different sediment and soil types, they testify to a pronounced sensitivity of geophysical properties to precipitation, exceeding these of MAP- δ13C derived climofunctions. We aim to test multiple climofunctions for geophysical properties using an extended precipitation-calibration range (up to ~1200 mm/a) at the Köndringen loess-palaeosol-sequence (LPS). This site mostly consists of polygenetic palaeosols and pedosediments of varying development that are in parts intersected. This testifies to a complex local geomorphological evolution and consequently, provides a difficult and thus, promising testing environment for the climofunctions at test. A thorough evaluation of these is pivotal as different climatic settings, soil/sediment properties, geomorphological positions and provenance effects may influence the climate-sensitive iron-(hydr-)oxide composition and eventually constrains the applicability of climofunctions. We also directly compare our findings to climate-model output data to assess derived MAP calculations through an independent measure. We contribute a critical assessment to test the potential of climofunctions for geophysical properties for moister western Central European settings that show magnetic enhancement and/or distinct color hues indicative for the presence of goethite and/or hematite.
How to cite: Vinnepand, M., Zeeden, C., Sprafke, T., Ryzner, K., Paknia, M., Hofmann, F. M., and Preusser, F.: Testing rock magnetic- and colorimetric- based climofunctions at the Middle Pleistocene Köndringen loess-palaeosol-sequence, SW Germany, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22019, https://doi.org/10.5194/egusphere-egu26-22019, 2026.
Long-distance aeolian dust transport is fundamental in shaping dryland environments and adjacent deposition regions, influencing sediment budgets, soil development, and ecosystem functioning. The Eastern Mediterranean constitutes a key corridor for Saharan dust transport, yet multi-proxy studies linking depositional records with atmospheric transport modelling are scarce. This study presents new insights into the provenance, transport dynamics, and seasonal variability of long-range aeolian dust deposited on the island of Crete (Greece), integrating laboratory sediment analyses with simulated air-mass trajectories.
Deposition samples were collected over a 15-month period at seven sites across western Crete, complemented by analyses of local surface material and reference aerosols from North Africa. Mineralogical composition, grain-size distribution, and radiogenic isotope ratios (Nd, Pb, Sr) reveal that deposited material is dominated by long range transported Saharan dust, with only minor local contributions. The persistent presence of palygorskite, uniform silt-dominated grain-size spectra, and isotopic signatures distinct from local substrates clearly indicate a North African origin. Temporal variability greatly exceeds spatial variability, and no substantial topography-related sorting is observed across the Lefka-Ori mountain range.
Seasonal shifts in mineralogical assemblages and isotopic composition indicate changes in dominant source regions, ranging from northeastern Algeria during winter to northeastern Libya and northwestern Egypt in summer, with transitional phases in spring and autumn. Transport-related fractionation is reflected in the depletion of coarse grain-size fractions and soluble minerals such as gypsum, as well as in variable illite/kaolinite ratios, pointing to mixing of particles from multiple source areas rather than single-source contributions.
To evaluate the plausibility of these interpretations and to assess the added value of combining depositional records with atmospheric modelling, laboratory-derived provenance indicators were compared with backward trajectories calculated using the HYSPLIT model for days with increased dust concentrations in the deposition region. The comparison highlights how the integration of mineralogical and isotopic fingerprints, deposition and concentration measurements, and modelled air-mass trajectories enhances the resolution of dust source attribution beyond what each approach can achieve independently.
This combined methodological framework advances our understanding of aeolian processes in large-scale aeolian systems and demonstrates the potential of integrated proxy-model approaches for reconstructing dust dynamics, with implications for geomorphic processes, and human environment interactions in dust-affected regions.
How to cite: Bitzan, S., Blanchet, C. L., Pichat, S., Christidis, G. E., Schepanski, K., and Kirsten, F.: Tracing Saharan dust to the Eastern Mediterranean: Integrating mineralogical and isotopic proxies with atmospheric trajectory modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19146, https://doi.org/10.5194/egusphere-egu26-19146, 2026.
Aeolian sedimentary systems record past climate changes due to their sensitivity to environmental variables, such as changing rates of sediment supply, climate, wind regime and palaeoflow, the action of physical, chemical and biogenic stabilising agents, and also interactions with other coeval sedimentary systems. Due to the interplay of allogenic and autogenic controls, the preserved sedimentary record of aeolian systems is highly complex and exhibits a variety of sedimentary architectures and spatial heterogeneities in facies distributions. Meanwhile, the accumulated deposits of aeolian sedimentary successions form important potential subsurface geothermal reservoirs and underground repositories for large-scale carbon capture and storage in both depleted and repurposed hydrocarbon reservoirs, and in very large saline aquifer bodies. In this study, a novel rule-based forward stratigraphic model, the Dune Architecture and Sediment Heterogeneity model (DASH), is used to investigate the variations in facies heterogeneity across different types of dunes, taking into account their sizes, migration rates, and aggradation rates over a broad spectrum of temporal scales. The DASH model is a geometric-based model that can reproduce different hierarchies of sedimentary architectures and bounding surfaces of aeolian dune and interdune and fluvial dune, barform and sheet-like deposits. The modelling outputs will enable more accurate predictions and systematic analysis of facies spatial distributions in different aeolian systems, including transverse dunes, linear dunes, and superimposed dunes. The modelling outputs can further be employed for predictions of petrophysical heterogeneity, for example, to guide models to assess geothermal reservoir potential and to model carbon capture and storage scenarios.
How to cite: Yan, N., Colombera, L., Mountney, N., and Cosgrove, G.: Linking Dune Dynamics to Facies Heterogeneity in Preserved Aeolian Systems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6041, https://doi.org/10.5194/egusphere-egu26-6041, 2026.
Studies have demonstrated that >~100 absolute ages of aeolian sand at certain spatial/vertical resolutions are necessary for constructing a reliable chronological framework for palaeoenvironmental/palaeoclimatic interpretations of dunefield histories (Telfer and Hesse, 2013). As acquiring such an interpretable dataset demands significant resources, several approaches, such as portable-OSL-OSL age estimates, have attempted to partly overcome this necessity (Stone et al., 2019).
Encroaching dunes in the past and present, dam drainage systems. In arid environments this process generates proximal upstream, dune-dammed waterbodies. These waterbodies that are often seasonal, deposit distinct, low-energy, fluvial, fine-grained sediments (LFFDs), often as sedimentary couplets. When dry, the water-body deposits sustain a playa morphology. This recurring aeolian-dominated, aeolian-fluvial process gradually leads to amplified LFFD accumulation, and partly reconfigures dunefield, and particularly dunefield margin, landscape evolution. In medium-sized basins (~10-200 km2) along the margins of the northwestern (NW) Negev desert dunefield of Israel, LFFD stratigraphic buildup gradually levels with dune-dam crest elevation, consequently leading to a dune-dam break outburst flood. The dune dam break in turn generates rapid fluvial incision of the LFFDS, reviving an open, fluvial-dominated environment in a transformed landscape (Robins et al., 2022,2023).
The INQUA DuneAtlas of global inland dunefield chronological data includes some dated samples that are non-dune sediments such as interdune and LFFD samples (Lancaster et al., 2016). However, the complementary contribution of such sediments to interpreting dunefield chronologies has not been fully assessed. Also, DuneAtlas sand samples dating to the LGM are sparse.
Here, we demonstrate for the NW Negev dunefield that OSL-dating, partly supported by port-OSL profiling, mainly of sandy units within LFFDs, improves the resolution and reliability of determining dunefield chronologies. The approach also gleans information on the morphological maintenance of existing dunes, and in some cases, reveals sand mobilization episodes that are absent in adjacent dated, dune cores.
Spatially dense, OSL-dated dune cores and sections of the ~103 km2-sized NW Negev dunefield revealed that the dunefield was constructed in two main sand incursions and vegetated linear dune (VLD) buildup/extension periods – associated with the Heinrich 1 (H1) and Younger Dryas (Roskin et al., 2011). In this study, exposed OSL-dated LFFD sections along the upstream-facing, dunefield margins revealed that dune-dammed waterbodies partly to completely erode earlier dunefield-margin dunes but also preserve remains of eroded dunes between LFFD units. This partial preservation of aeolian deposits enables the construction of a reliable archive. The LFFD sections also revealed evidence of significant and initial dune incursion and damming during the LGM, intermittently recurring until the early Holocene (Robins et. al.). Early Holocene LFFDs may imply partial dune buildup or equilibrium-like dune maintenance, and/also, a significant lag between Younger Dryas dune-damming and dune-dam breaching. Altogether, dating dunefield LFFDs is proposed to be a primary approach for jointly studying dunefield and fluvial histories.
References
Lancaster, N., et al., 2016. QI
Robins, L., et al., 2022. QSR
Robins, L., et al., 2023. QSR
Roskin, J., et al., 2011. QSR
Stone, A. et al. 2019. QG
Telfer, M.W. and Hesse, P.P., 2013. QSR
How to cite: Roskin, J., Robins, L., and Greenbaum, N.: Dune-dammed waterbody, aeolian and fluvial sediment chronologies improve resolution of dunefield histories, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3582, https://doi.org/10.5194/egusphere-egu26-3582, 2026.
Australia’s dryland margins are increasingly vulnerable to drought, flood and fire. Investigating past landscape and climate conditions using evidence preserved within landforms and their sediments provides important context for past, present and future climate-coupled water availability and landscape change. Such work is challenging in the Australian context, however, due to the sparse preservation of paleoenvironmental records and high spatial heterogeneity. Our study focuses on the Wimmera catchment, located on the dryland margins of south-eastern Australia, which is an understudied region of high agricultural, ecological and cultural importance. The landscapes of the Wimmera comprise a unique overflow-lake system with well-preserved shoreline dunes. Shoreline dunes form valuable archives of past hydrologic lake conditions in this semi-arid region; deflation of the lake floor, and transport of these sediments onto the dunes, records preservation of the adjacent lake’s condition within the sediments. We combine optically stimulated luminescence (OSL) dating of single grain quartz to derive depositional ages, and a larger chronological dataset using portable OSL measurements, with facies characterisation from field observations and grainsize measurements, to provide first insights into the rich history preserved within these lake shoreline dunes.
How to cite: Schwarz, V., Lauer, T., Gunn, A., Tsukamoto, S., Aboriginal Corporation, B. G. L. C., and Fitzsimmons, K. E.: Paleoenvironmental history preserved in shoreline dunes of the Wimmera lake overflow system, Wotjobaluk Country, south-eastern Australia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-572, https://doi.org/10.5194/egusphere-egu26-572, 2026.
The hyper-arid conditions of the Namib Sand Sea in the present day pose significant challenges for all but some extremely well-adapted species. The presence of a rich-archaeological surface record of stone age lithics at numerous interdunal pan sites raises questions around the evolution of this environment throughout the Quaternary. Specifically, was this region subject to phases of elevated humidity, allowing the proliferation of a network of ‘green corridors’ through which hominin populations exploited this landscape, or were hominins adapted to hostile conditions much like those of today?
Earlier insights into the palaeoenvironmental context of interdune pan sites were provided by Teller et al. (1990), although this was before the development of chronological techniques that could provide reliable age constraint on sediments greater than 100 ka, where we have found the quartz luminescence signal to be in saturation. Feldspar dating protocols will allow us to provide age control for the later part of the Earlier Stone Age and the Middle Stone Age (e.g. Stone et al., 2024). The PANS project (Palaeoenvironmental context of Palaeolithic Archaeology in the Namib Sand Sea) applies single grain and multiple grain multiple elevated temperature infrared-stimulation luminescence (MET-IRSL) alongside a multi-proxy approach to environmental reconstruction at new sites in the northern Namib Sand Sea to situate environmental change and patterns of hominin activity within the regional palaeoclimatic framework. We present MET-IRSL results alongside palaeoclimatic proxies and explore the use of palaeoecological markers, at key new sites visited in 2025. We combine these datasets with remote sensing techniques to reconstruct former watercourses in this hyper-arid environment.
Stone, A., Leader, G., Stratford, D., Marks, T., Efraim, K., Bynoe, R., Smedley, R., Gunn, A. and Marais, E., 2024. Landscape evolution and hydrology at the Late Pleistocene archaeological site of Narabeb in the Namib Sand Sea, Namibia. Quaternary Science Advances, 14, p.100190.
Teller, J.T., Rutter, N., Lancaster, N., 1990. Sedimentology and paleohydrology of Late Quaternary lake deposits in the northern Namib Sand Sea, Namibia. Quat. Sci. Rev. 9, 343–364.
How to cite: Spano, T., Stone, A., Leader, G., Bynoe, R., Marks, T., Stratford, D., Efraim, K., Karamitrou, A., Bateman, M., Gunn, A., Marais, E., and Singh, V.: Exploring the palaeoenvironmental context of surface archaeology in the Namib Sand Sea, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21262, https://doi.org/10.5194/egusphere-egu26-21262, 2026.
Small endorheic basins at the arid, northwestern Negev desert dunefield margin were hypothesized to preserve finely resolved and quasi-continuous archives of climate‑driven sediment dynamics. Two 7.5‑m deep cores from the Givat Hayil dune‑dammed playa (0.047km2) captures sedimentation processes and erosion rates of a small, ~2 km2 basin, characterized by ~1 short-lived flood per annum. A multi‑proxy approach combined laser‑diffraction grain‑size analysis and imaging, X‑ray fluorescence geochemistry, and portable-OSL (port‑OSL) profiling to diagnose the sediments, identify accumulation trends, delineate stratigraphic boundaries and target samples for OSL dating.
The cored sequence documents transitions between fluvial to aeolian dominated environments, from the onset of MIS-3 until today, and mainly since the Younger Dryas (YD). Basal, well‑bedded silt loams dating to the early MIS-3 suggest floodplain deposition of up-basin-sourced, primary, MIS-6-MIS-2 (calcic) loess deposits, indicative of initial and enhanced basinal loess erosion evolving into hyper-concentrated flows. A long MIS-3 - YD hiatus suggests significant decrease in loess erosion rates. YD - early Holocene aeolian sand influx led to the playa-forming dune dam. During the Holocene, the playa efficiently trapped sediments undergoing varying upbasin fluvial erosion rates and ongoing dustfall, punctuated by anthropogenically-induced Roman-Byzantine sand mobilization. Thin units with diluted aeolian sand content probably indicating rapid pulses of eroded up-basin loess delivery driven by high-intensity rain events are interpreted to document major and altogether, evenly distributed, ~1:1,000 yr recurring floods.
Changing sediment accumulation rates appears to capture a complete and fluctuating erosion trajectory of up-basin loess—from a MIS-3 loess‑loaded landscape to a present loess-starved basin. Inversed magnitude-lower loess erosion rates along the Late Pleistocene–Holocene transition in relation to the Holocene, despite higher up-basin loess availability, probably reflects a moister Late Pleistocene that enhanced vegetation and crust development, that in turn, increased loess preservability. Three-fold larger late Holocene accumulation rates in relation to the early Holocene, despite depleting up-basin loess availability, may be a result of higher erosion rates due to more high-intensity rainfall events, in line with gradually increasing aridity.
Altogether, this underrecognized, high‑resolution archive demonstrates how sediment archives of small, dunefield fringe endorheic basins can serve to resolve the timing, magnitude, and mechanisms of both aeolian and fluvial processes, in particular extreme floods and erosion rates, in arid and hyper-arid environments.
How to cite: Golovaty, N., Roskin, J., Vainer, S., and Faershtein, G.: Late Quaternary palaeohydrology, aeolian dynamics and erosion rates recorded in a small, dune-dammed, arid dunefield margin playa, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4809, https://doi.org/10.5194/egusphere-egu26-4809, 2026.
The Atacama Desert, along the Pacific margin of the Central Andes, is one of the driest high-altitude regions on Earth, with hyperaridity persisting for at least 10-12 Ma due to its latitudinal location, Humboldt Current and Andean orographic barriers. This has produced landscapes with exceptionally well-preserved Quaternary geomorphologies, including mega-landslides, alluvial terraces and fans. While the roles of tectonics and climate in shaping and controlling these features remain debated, recent regional studies suggest the occurrence of past humid periods, though their timing, duration, moisture sources and controlling mechanisms remain largely unresolved.
We conducted a multi-proxy study of a 20-30 m thick and 300 m long sedimentary sequence trapped behind the Caquilluco mega-landslide (~2000 m a.s.l., Pleistocene). This site provides a rare exposure of lacustrine deposits and natural dam that have been partially re-incised. To reconstruct depositional conditions, document the paleoenvironment, and constrain the chronology, our analyses included stratigraphy (facies, grain size), geochemistry (XRF) and paleoenvironmental indicators (diatom, pollen) combined with feldspar OSL and ¹⁰Be exposure dating.
Results indicate predominantly lacustrine conditions, through fine and regularly deposited sediments. Slumps in distal deposits suggest minimum water depths of several meters, while desiccation cracks and debris flow layers indicate intermittent drying events. Although only partially preserved, pollen and diatom assemblages point to a semi-humid paleoenvironment, dominated by shallow-water taxa. OSL dates constrain deposition of the exposed sequence to 133 ± 14 ka – 115 ± 16 ka, corresponding to MIS 5e and consistent with ¹⁰Be exposure ages of dam and gorge incision. Given the small catchment area (~10 km²) and high evaporation rates, sustaining lacustrine conditions over ~20 ka would require substantial precipitation. We hypothesize that strong Pacific surface temperature anomalies during MIS 5e may have induced semi-permanent "El Niño"-type conditions, aligning with other regional proxies supporting enhanced humidity in the Atacama Desert during the last interglacial.
This study highlights the value of high-altitude drylands as archives of Quaternary environmental change and demonstrates the potential of lacustrine deposits in reconstructing past hydroclimatic variability, providing insights into the interplay of climate, geomorphology, and hydrology in dryland evolution.
How to cite: Nieslony, M., Zerathe, S., Valla, P., Ochoa, D., Albinez, L., Gomez, D., Delgado, F., Robert, X., Audin, L., Braucher, R., and Taillefer, A.: Multi-millennial increased humidity in the Atacama Desert during MIS 5e: evidence from a lacustrine record in southern Peru, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14484, https://doi.org/10.5194/egusphere-egu26-14484, 2026.
Despite the modern hyperaridity of the Atacama Desert (mean annual rainfall <1 mm), evidence for wetter climates during the Holocene have been found in cores from salars (i.e., salt flats) and sedimentary basins. There are several major discrepancies in the Holocene climate of the Atacama Desert after the Last Glacial Maximum, including asynchronous wet phases in the Coastal Cordillera and the Altiplano as well as a discordance between paleo-wetland and Salar de Atacama chronology. We address the following research question: How did fluvial and mass flow activity in the Atacama Desert respond to regionally fluctuating hyperaridity throughout the Quaternary period? A series of large alluvial fans sourcing from the western Andean foothills that terminate at these salars remain largely underutilized as a paleoclimate record, though alluvial fan stratigraphy is often used to reconstruct past environmental conditions. These alluvial fans, which may serve as a bridge between competing paleoclimate signals, have modern transport and depositional processes that include layered, overbank mudflows that extend laterally for up to hundreds of meters from the channel, aeolian reworking of inactive fan surfaces, and terminations in playa-like environments. To determine how fan activity is tied to Quaternary climate change, we made detailed stratigraphic correlations of 6 sedimentary facies across 18 study sites along the fan sourcing from Quedabra de Chacarilla. We then used single-grain post-infrared infrared stimulated luminescence (post-IR IRSL) to precisely date 11 samples taken from interpreted aeolian-deposited facies within the stratigraphy. Detailed chronology of the fan stratigraphy using post-IR IRSL will allow us to compare with other regional climate proxies and understand how Atacama alluvial fans record and preserve evidence of past climate evolution. This will advance our understanding for how future climatic changes in the region may impact people and infrastructure due to mudflow-based flooding.
How to cite: Rogers, E., Palucis, M., and Morgan, A.: Constraining the paleoclimate of the Northern Atacama Desert, Chile using luminescence dating of alluvial fan stratigraphy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-775, https://doi.org/10.5194/egusphere-egu26-775, 2026.
Aeolian erosion of the alluvial deposits in the hyper-arid core of the Atacama Desert appears in several sites in the form of deflation hollows. Despite constituting signs of degradation of the unique and ancient landscape, their architecture and formation is as yet poorly understood. Ground-penetrating radar (GPR) is an effective way to image the internal structure of such aeolian landforms, and in this study, eight 200-500 m GPR profiles were acquired across deflation hollows and an eroded alluvial fan. A 400 MHz antenna was used, penetrating more than 3 m deep. Evaporitic crusts and salt-cemented layers were identified and mapped. In the leeward side of hollows, younger aeolian deposits can be differentiated from the older alluvial sediments, and similarities were found in the radar facies of several eroded surfaces. This work reveals the shallow subsurface architecture of the aeolian cover and alluvial deposits and provides new insights into the landscape formation in hyper-arid environments through the use of GPR.
How to cite: Schwarze, P., Igel, J., Yogeshwar, P., Blanco Arrue, B., Walk, J., and May, S. M.: Subsurface architecture of aeolian erosion features in hyper-arid alluvial systems of the Atacama Desert: Insights from ground-penetrating radar, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2431, https://doi.org/10.5194/egusphere-egu26-2431, 2026.
The Central Iranian Plateau is a key region for understanding Late Quaternary landscape evolution. However, palaeoenvironmental reconstructions remain limited due to harsh climatic conditions and difficult access. The Khoor va Biabanak Basin, at the eastern edge of the Great Kavir, preserves diverse geomorphological archives that record interactions between climate and surface processes.
We used an integrative approach combining geomorphological mapping, stratigraphical analyses, and luminescence dating of 12 sedimentary sequences across eight geomorphic units, including pediments, alluvial fans, dunes, sand sheets, and playa surfaces.
Quartz OSL signals from dunes and sand sheets were generally dim and dominated by medium and slow components. Dose recovery tests show limited reliability, with high failure rates for recycling and recuperation, although performance improved at preheat temperatures of 180-280 °C. OSL-IR depletion tests indicate feldspar contamination in ~21% of aliquots, limiting the applicability of quartz OSL in this setting.
Preliminary K-feldspar pIRIR225 results are more promising. Fading rates range from 0.5–2.3% per decade, and residual doses are 2–5%. The first age estimates are currently in progress and will provide essential chronological constraints for Late Quaternary geomorphological processes in the basin.
The oldest landforms indicate alternating pediment erosion, alluvial fan deposition, dune activity, and soil formation, likely corresponding to periods before and during MIS 3. Subsequent alluvial fan progradation and dune development reflect cold and arid conditions during the Last Glacial Maximum. Holocene features show increasing aridity, including gypsum-rich soils, dune reactivation, and deflation of playa surfaces. In the future, with the completion of dating results, these observations will allow a robust reconstruction of Late Quaternary landscape evolution and its climatic drivers in the Khoor Basin.
This study provides the first comprehensive model for landscape evolution in the Khoor va Biabanak Basin, demonstrating both the potential and limitations of luminescence dating in arid-region environments and highlighting the complex interactions between climate, geomorphology, and sedimentary processes in Central Iran.
How to cite: Torabi, M., Kolb, T., Fattahi, M., Buedel, C., Rashidi Koochi, Z., and Fuchs, M.: Late Quaternary geomorphological processes and landscape evolution in the Kkoor va Biabanak basin using quartz OSL and K-feldspar pIRIR225 ages, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7403, https://doi.org/10.5194/egusphere-egu26-7403, 2026.
Carbonate nodules are pedogenic carbonates commonly found in regions of high evapotranspiration, such as arid and semiarid areas. The stable carbon isotopes in these nodules are influenced by the type of vegetation (C3 or C4 plants), while the stable oxygen isotopes are controlled by soil water and temperature. Carbonate nodules persist in the soil, and their isotopic signatures can reflect the paleoclimatic conditions under which they formed. Carbonate nodules are distributed across the alluvial plains of southwestern Taiwan; however, the present humid conditions may not be favorable for their formation. The objective of this study was to evaluate the climatic conditions and vegetation types that influenced the formation of carbonate nodules using stable carbon and oxygen isotopes. Four pedons with different ages of soil formation were sampled in accordance with marine transgression and regression phases, corresponding to 10,000 years before present (yr BP), 8,000 yr BP, 5,000 yr BP, and 3,000 yr BP. Carbonate nodules were collected from the pedons, and their stable carbon and oxygen isotopes were analyzed using an automated carbonate preparation device. The δ13C values indicated a mixed C3/C4 vegetation, with a predominance of C4 plants (68.0 to 98%). The mean annual temperature (12.3-14.0°C), calculated using the climofunction of temperature and δ18O, was lower than the present (24.7°C). The mean annual precipitation (1036 to 1342 mm yr-1), calculated from the geochemical climofunction, was also lower than the present (1829 mm yr-1). The radiocarbon ages of the carbonate nodules ranged from 4063 yr BP to 690 yr BP, implying that climatic conditions may have been drier and cooler than present during this time frame. This may be due to a weaker East Asian Summer Monsoon, which favored calcification in the soils. These climatic conditions are consistent with the formation environment of carbonate nodules.
How to cite: Hum, H. Z., Wang, P.-L., Huang, W.-S., and Hseu, Z.-Y.: Stable carbon and oxygen isotopic composition in carbonate nodules from alluvial soils and their implications for paleoclimate in Taiwan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4748, https://doi.org/10.5194/egusphere-egu26-4748, 2026.
Unlike the modern hyper-arid conditions across most of the Arabian Peninsula, the region experienced pronounced humid phases during the Quaternary, supporting a dense vegetation cover. Evidence for these humid periods and the associated greening is documented in regional geological and paleoenvironmental records, including speleothems, lake-level reconstructions, lacustrine sediment sequences, and the presence of soil carbonate. However, the timing, extent, and moisture sources of these humid phases remain poorly constrained in the northern Arabian Peninsula, particularly in the area now occupied by Kuwait. There is evidence that the area once experienced wetter intervals, but it is unclear whether they were driven by incursions of a Tropical Ocean monsoon (summer) or by enhanced Mediterranean (winter) westerlies.
This study investigates the nature of Quaternary humid conditions in Kuwait using petrographic, mineralogical, and oxygen- and carbon-isotope analyses (δ¹⁸O and δ¹³C) of relict pedogenic and paleosol carbonates. A total of 84 soil samples were collected across 21 sites in Kuwait, targeting calcic and petrocalcic horizons. Petrographic thin sections show progressive stages of carbonate development from stages I to III. Stage III carbonates are older and have δ¹⁸O values that cluster between −12 ‰ and +3 ‰ (VPDB) and δ¹³C values between −9 ‰ and 0 ‰. These ranges reflect the coevolution of soil moisture sources and vegetation types. During monsoon-influenced intervals, long-distance moisture transport and the amount effect produce isotopically light rainfall, resulting in carbonates with more depleted δ¹⁸O values. In contrast, carbonates have more isotopically enriched δ¹⁸O values during periods influenced by Mediterranean winter westerlies. The δ¹⁸O values of stage III soil carbonate suggest moisture sourced from both the tropical monsoon and the Mediterranean. Lower δ¹³C values reflect the contribution of soil-respired CO₂ from C₃ plants, whereas higher δ¹³C values reflect a greater contribution of C₄ plants. The δ¹³C values of stage III soil carbonate in Kuwait clearly reflect humid phases sourced from the tropical monsoon and supporting C4 vegetation, as well as winter rainfall from the Mediterranean and supporting C3 vegetation. The determination that Kuwait has experienced wetter conditions in the past from both tropical and Mediterranean sources is important for determining potential future precipitation amounts.
How to cite: Al-Qattan, N., Rech, J., and Currie, B.: What Caused the Greening of Kuwait: An Isotopic Investigation of the Source of Moisture During Quaternary Pluvial Periods in Kuwait, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15946, https://doi.org/10.5194/egusphere-egu26-15946, 2026.
