Orals: Wed, 6 May, 10:45–12:30 | Room 0.31/32
We present a database of AMS radiocarbon dates from Lake Baikal sediment cores, encompassing 51 cores and 518 dates, providing a complete record from literature spanning 1992 to 2025 (with transcription errors corrected) and including 22 previously unpublished dates from cores CON01-603-5 and CON01-605-5. The most common material used for radiocarbon dating in our dataset is total organic carbon (TOC). Unfortunately, the interpretation of TOC ages in lake sediments is hindered by issues such as the reservoir effect, in situ contamination by old organic carbon, and/or the hardwater effect. These issues may culminate in age estimates thousands of years older than the true depositional age of that sediment, which we term the “age offset”. Linear regression of uncalibrated radiocarbon dates has been used to estimate the age offset in Lake Baikal, with results ranging from 0 to 1.5 14C kyr in different cores. Estimates from other methods have returned estimates of approximately 2 14C kyr BP. Despite this, most previous studies have not incorporated age offset uncertainty in their age depth modeling, or have included uncertainty of, at most, ± 0.09 14C kyr. Furthermore, the varying age offset estimates have been interpreted by some as evidence that different regions of Lake Baikal have different age offsets, with implications as to the cause of the age offsets. We use the database to review the use of linear regression on uncalibrated radiocarbon ages as a method for estimating age offsets of TOC. We apply the linear regression age offset method to all suitable cores in our database, returning 21 estimates of age offset from throughout the lake. Our results provide no statistically significant evidence for a systematic difference in age offset in different regions of Lake Baikal (specifically Academician Ridge and Buguldeika Saddle). Our results return a lake-wide TOC radiocarbon age offset of 1.62 ± 0.76 14C kyr, suggesting previous studies in Lake Baikal have significantly underestimated the temporal uncertainty of radiocarbon ages from TOC. Finally, our results are a caution that linear regression-based age offset estimates in lake sediments have a large uncertainty that might only be observable with multiple datasets.
How to cite: Newall, S., Mackay, A., Piotrowska, N., and Blaauw, M.: A Complete Database of AMS Radiocarbon Estimates from Lake Baikal Sediment Cores with a Lake-Wide Assessment of TOC Age Offsets, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2461, https://doi.org/10.5194/egusphere-egu26-2461, 2026.
Although geomorphic and pedogenic proxies have proved the occurrence of pluvial episodes in arid regions of central Iran during the late Quaternary, precise timing of such events have remained unclear and have been under debate for long time. Pedogenic carbonates can provide insight into the timing of soil leaching and pluvial periods. Therefore, the aim of this study was to establish an accurate chronology based on pedogenic carbonates and using radiocarbon to understand the regional and global temporal correlations of pluvial events in eastern Isfahan (central Iran). For this purpose, two palaeosols having non-calcareous gravels on the summit of alluvial landforms were selected. Macromorphology of the carbonates was checked in the field and submicroscopy was studied by scanning electron microscopy. Radiocarbon analysis was performed using accelerated mass spectroscopy (AMS) at ETH Zurich and the ages were calibrated using OxCal 4.4 software. In addition, the d13C values for both the soil matrix and pedogenic carbonates was measured using mass spectroscopy. The pedogenic carbonates occurred predominantly as gravel coating in the Bk and as fine nodules in Btk horizon. Submicroscopic analyses of the carbonates showed the abundance of micritic and microsparic rhombohedral crystals of calcite without signals of recrystallization or overprinting. The d13C values indicated that the upper ~50cm of the pedons were influenced by calcareous dust input. Radiocarbon dating of deep carbonates revealed the existence of at least four phases of considerable leaching and, thus, humid conditions: around 42.2–39.5, 39.3–36.2, 31,6–29.2 and 26.9–26.0 ka BP, i.e., during marine isotope stage (MIS) 3a and 3b. These ages correlated well with regional paleoclimatic proxies in the Levant and NE Syria suggesting the impact of the Mediterranean cyclones and westerlies and the increase in precipitation in the region. The global correlation of our ages with Greenland ice core records demonstrated that wet periods in central Iran were in agreement with periods of low oxygen isotope values (stadial periods) in Greenland suggesting a climatic teleconnection between North Atlantic and western Asia.
How to cite: Bayat, O., Karimi, A., and Egli, M.: Late Quaternary pluvial episodes in a dryland of central Iran: insights from a radiocarbon chronology of pedogenic carbonates, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3872, https://doi.org/10.5194/egusphere-egu26-3872, 2026.
The geosciences reveal Earth's past by analyzing the record from ancient terrains that document the planet's evolution. Ancient U-deposits, in particular, deserve careful study. The ore is a product of environmental conditions resulting from interactions among Earth's spheres (i.e., the lithosphere, hydrosphere, atmosphere, and biosphere) and from Earth's evolution over time. The U mobility and U-compound formation are determined by environmental conditions such as oxidation state, pH, and the nature of the geochemical reservoir. Both are the result of geological processes (e.g., magmatism, weathering, hydrothermalism), tectonic context (e.g., subduction zones, rifting, collisional episodes), and geochemical conditions (e.g., the availability of free O2 in the atmosphere).
The main Brazilian target for uranium, the Lagoa Real Uranium Province (LRUP), for example, comprises rocks ranging from Archean to Neoproterozoic. It is typically viewed as a metasomatic, high-grade metamorphic deposit. Uraninite (UO2) is the main ore mineral, associated with high-F biotite and evidence of disilicification, reflecting a reducing environment, low pH, and high F availability. These data indicate a low free O2 paleoenvironment (e.g., at high depth and/or in an ancient stage before the Great Oxygenation Event - GOE), with contact with high HF concentrations during rifting episodes, followed by orogenic collisional events. However, this is not the only mineralization stage: uranil minerals indicate high free O2, resulting from weathering under an oxidized atmosphere after the GOE.
Thus, the rocks preserve superposed processes resulting from distinct geochemical and tectonic contexts, some of which are partially or fully obliterated. Despite this, these rocks provided geochemical, petrographic, and field data that enabled the recovery of the ancient geological record. The LRUP has undergone the opening and inversion of overlapping rifts, as well as A-type magmatism, metamorphism, and metasomatism. It has also witnessed some of Earth's major evolutionary events since the Archean, such as the incorporation of U into the crust from the mantle and atmospheric oxygenation. Currently, a previously unknown process has been identified at LRUP: partial melting linked to regional metamorphism that may be related to Pan-African Cycle collisional episodes (900 to 500 Ma). The relevant record was preserved at the macroscale, microscale, and likely nanoscale. At the outcrop, leucosome appears parallel to shear zones or fills fold axes and low-pressure zones. Drill cores reveal melt segregating from the residual mafic lithologies and increasing LREE concentration with increasing melting in the residua. At the micro- to nanoscale, SEM studies show that mono- and polymineralic zircon inclusions have distinct compositions, which may reflect different formation stages. Core inclusions include K-feldspar, quartz, and fluorite. Towards the margin, inclusions shift to K-feldspar, albite, and quartz. At the very edge, inclusions are Co- and As-bearing calcite with REE minerals.
Therefore, in addition to the social and economic implications, there are other benefits from investigating ancient U-deposits. Despite their complexity, they may preserve a record of Earth’s long past, revealing interactions among Earth’s spheres, changes in the lithosphere, and helping geoscientists understand the main large-scale processes, or global cycles, that shape the planet.
Keywords: geological record, uranium deposits, partial melting.
How to cite: Azevedo, R. A., Rios, F. J., Hernández, C. R., and Barredo, F. J.: The Earth's past: recovering the geological record from a Uranium deposit, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10522, https://doi.org/10.5194/egusphere-egu26-10522, 2026.
Quaternary lava plateaus profoundly modify landscapes by filling the lowlands, disrupting drainage systems, controlling long-term fluvial evolution and leveling the pre-existing topography. To constrain the spatiotemporal evolution of these processes, robust geochronological data integrated with subsurface stratigraphic information are required. In this study, we aim to re-evaluate the timing and number of basaltic eruptions in the Yeoncheon lava plateau and to reconstruct the spatiotemporal evolution of the lava plateau and associated paleo-channels using field surveys, borehole stratigraphy, and high-precision 40Ar–39Ar geochronology supported by GIS-based analyses.
A total of 19 boreholes penetrating from upper Quaternary deposits down to the underlying basement were analyzed, together with detailed field surveys of well-exposed outcrops along river corridors. Basalt samples from boreholes and outcrops were dated using 40Ar–39Ar dating methods, providing independent absolute age constraints for lava emplacement. The results indicate the presence of basalt units emplaced during two distinct eruptive periods, with weighted mean ages of 518 ± 2 ka and 168 ± 1 ka. These basalts are geochemically distinguishable and show systematic elevation-dependent distributions, with the older basalt generally occurring at elevations of ~50–55 m a.s.l. and the younger basalt distributed at ~65–70 m a.s.l.
Based on integrated evidence from borehole stratigraphy, basalt age–elevation relationships, and comparison with GIS-based topographic data, we identify the presence of at least two paleo-channels and constrain the timing of drainage reorganization leading to establishment of the present Hantangang River. The first paleo-channel between ca. 518 and 168 ka, is inferred to have incised the older lava plateau and basement rocks prior to emplacement of the younger lava, which preferentially filled this topographic depression. The second paleo-channel formed after ca. 168 ka and is inferred to have passed through a low-lying area within the lava plateau, now known as the Eum-teo town, where surrounding basalt cliffs and the scarcity of basalt in boreholes indicate sustained headward erosion. Finally, geomorphic evidence from river terrace development indicates that subsequent drainage reorganization led to establishment of the present Hantangang River after ca. 35 ka.
This study demonstrates that borehole-constrained chronologies significantly reduce uncertainties in volcanic stratigraphy and provide a robust temporal framework for reconstructing paleo-channels and landscape evolution in lava plateau environments. By integrating absolute dating with borehole data, this approach enables reconstruction of spatiotemporal changes in lava plateau development and associated drainage reorganization. The framework is transferable to other lava plateau systems and offers broad potential for resolving long-term environmental change in Quaternary landforms.
How to cite: Kwon, J., Kim, J. C., Han, M., Kil, Y., Hong, S. S., and Choi, H.: Reconstruction of paleo-channels and the spatiotemporal distribution of the Yeoncheon lava plateau, South Korea, constrained by borehole data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15875, https://doi.org/10.5194/egusphere-egu26-15875, 2026.
The half-lives of 234U and 230Th are fundamental constants for U-series disequilibrium dating, as are well-characterized reference materials such as Harwell Uraninite (HU1) and CRM112A. Approximately a decade ago, the half-life values most widely used in Th/U dating were refined using multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) (Cheng et al. 2013), achieving precision levels of ±260 years for 234U and ±110 years for 230Th. More recently, internal statistical uncertainties for the 234U half-life have been reported to approach ±25 years through the use of high-ohmic resistors, careful compensation for isotope abundance differences using reference materials, and rigorous evaluation of instrumental tailing (Hu et al. 2025).
Here, we present precision tests performed with an MC-ICPMS equipped with high-ohmic resistor combinations on secular-equilibrium speleothem samples from Wilder Mann Cave (>2 Ma). Data were processed following the baseline and treatment protocols of Kerber et al. (2025), including cubic Hermite polynomial fits to characterize peak tailing and identification and quantification of uranium scattering (“ghost”) signals. Using this implementation, which combines 1013 Ω Faraday detectors with long-term gain stability tests, we determined U-series isotope ratios for the Wilder Mann samples bracketed by HU1 and calibrated against CRM112A. The resulting half-lives of 234U and 230Th are 245,810 ± 265 years and 75,580 ± 145 years, respectively, in agreement with previously published values. Additional experiments assessed the internal precision of 234U and 230Th measurements using a 1013 Ω Faraday cup and enabled re-evaluation of the equilibrium state of the HU1 reference material. We confirm that the HU1 batch used in this study is offset from secular equilibrium by ~1.5‰, consistent with earlier inferences. Finally, we apply this analytical setup to ancient cold-water coral samples from IODP Site U1317, demonstrating near–secular equilibrium behavior for materials older than 500 ka, with downcore ages extending to ~3 Ma based on Sr-isotope stratigraphy (Raddatz et al. 2014).
How to cite: Arul, K., Noelken, M., Frank, N., Warken, S., and Spoetl, C.: Impacts on precision of the half-lives of U234 and Th230 using the Neptune MC-ICPMS with high ohmic resistors, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20096, https://doi.org/10.5194/egusphere-egu26-20096, 2026.
The extent of the Northern Hemisphere ice sheets during Marine Isotope Stage 3 (MIS 3, 57-29 ka) is generally not well constrained due to limited stratigraphic control, lack of geological deposits, and inconclusive dates. For the Greenland Ice Sheet (GrIS), it is generally assumed that the ice extended beyond the present-day coast during MIS 3, although some data suggest that it might have had a more limited ice extent. In this study, we constrain the timing and extent of the west and northwest GrIS by modelling the inherited signal from the nuclide inventory of in situ 14C and 10Be. Our results show that the coastal areas of west and northwest Greenland were ice-covered during MIS 4, followed by a ~20 ka long period where the ice margin was located near the current ice margin before the Last Glacial Maximum (LGM). We furthermore find that the pre-LGM exposure must have occurred towards the end of MIS 3 to be captured by the in situ 14C signal. Finally, we find that the LGM advance likely began late and only exceeded the present coastline after 20 ka. Our results show that modelling the inherited in situ ¹⁴C and ¹⁰Be signals provides a new way to constrain MIS 4–2 ice fluctuations of Northern Hemisphere ice sheets.
How to cite: Rosenberg, A., Søndergaard, A. S., Knudsen, M. F., and Larsen, N. K.: Evidence of a reduced Greenland Ice Sheet during Marine Isotope Stage 3 based on modelling of in situ 14C and 10Be nuclides, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5566, https://doi.org/10.5194/egusphere-egu26-5566, 2026.
During the Late Pleistocene, climate instability and rapid environmental change strongly conditioned human dispersals and settlement dynamics in Central Europe, particularly at latitudes above 45°N. Southern Poland represents a key region for investigating these processes, as it functioned as a peripheral or “satellite” area within broader hunter-gatherer settlement systems, episodically occupied during phases of climatic amelioration. Reconstructing the timing and tempo of these occupations requires robust, high-resolution chronologies anchored by reliable geochronological tools.
This contribution presents new radiocarbon data from the open-air site of Piekary III (southern Poland), part of a larger complex of Middle and Upper Paleolithic localities situated along the Vistula River valley near Kraków. Excavated primarily in the early 20th century, Piekary III preserves a multi-layered stratigraphic sequence resting on Jurassic limestone. However, limitations in excavation documentation and uncertainties in artifact–layer associations have long hampered precise chronological interpretation, making the site an ideal case study for assessing the role of radiocarbon dating in complex Quaternary archives.
To establish a refined chronological framework for the site’s occupation, fifteen bone samples underwent collagen extraction using advanced ultrafiltration protocols at the Bologna Radiocarbon Laboratory (BRAVHO), followed by AMS radiocarbon dating. Particular attention was paid to collagen preservation and data quality in order to minimize analytical uncertainties and to identify potential outliers.
The resulting dates indicate that the main phase of Late Middle Paleolithic occupation occurred during MIS 3, spanning approximately 50–42 ka BP, with a more constrained cluster between ca. 42–41 ka BP. Two samples yielded significantly younger ages attributable to a Gravettian occupation, documenting a later Upper Paleolithic phase at the site and episodic reoccupation of the area during colder phases of the Late Pleistocene.
These results demonstrate the value of combining rigorous pretreatment protocols, critical evaluation of outliers, and stratigraphic information to constrain human–environment interactions at millennial scales. More broadly, the Piekary III case illustrates how radiocarbon dating provides an essential independent anchor for reconstructing settlement dynamics and environmental responses during periods of rapid climatic change in the Quaternary.
How to cite: Picin, A., Laura, T., Stefański, D., Tomaszewski, A. J., and Talamo, S.: Radiocarbon chronology of Late Pleistocene occupations at Piekary III (southern Poland), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21308, https://doi.org/10.5194/egusphere-egu26-21308, 2026.
Posters on site: Wed, 6 May, 14:00–15:45 | Hall X5
41Ca (half-life = 99 ka) is a cosmogenic radionuclide that has long been proposed as a promising dating tracer for geological and archaeological samples from Middle and Late Pleistocene. Calcium is abundant and has a residence time of 800 ka in the oceans, much longer than the half-life of 41Ca. This has led to the expectation of a uniform distribution of 41Ca/Ca ratios in oceans around the globe. Ocean deposits acquire the global seawater value of 41Ca/Ca upon the initial formation. Since ocean deposits are shielded from cosmic rays by overlying seawater, no cosmogenic 41Ca is produced as deposits grow older. These conditions are ideal for 41Ca dating of marine deposits.
However, the 41Ca/Ca ratio is typically less than 10⁻15 in the environment, posing significant challenges for their measurements. Recent advances in Atom Trap Trace Analysis (ATTA) have enabled the detection of 41Ca in geological samples. The lowest 41Ca/Ca ratio measured so far is 3 × 10−18, found in a foraminifer sample from the Pacific Ocean.
We measured the 41Ca/Ca ratios in seawater samples from various depths in oceans around the world and mapped the spatial distribution of 41Ca. This work identifies the critical initial 41Ca/Ca value for 41Ca dating of marine deposits. Building on these findings, we performed 41Ca dating on foraminifera and coral samples from the Pacific, South China Sea, and Southern Ocean, and compared the results with those obtained from other dating methods. Meanwhile, we are exploring the feasibility of applying 41Ca dating to other geological and archaeological samples.
How to cite: Zhu, H.-M., Sun, W.-W., Bender, M., Huang, E.-Q., Huang, H., Jiang, W., Lu, Z.-T., Tian, J., Xia, T., and Yang, G.-M.: A 41Ca chronometer for Pleistocene marine archives, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8523, https://doi.org/10.5194/egusphere-egu26-8523, 2026.
Counting annual-scale cycles can yield extremely high-precision chronological models. However, this process is typically performed by inspection, often making it time-consuming and subjective. While various software packages exist that automate this process, many researchers still count manually because of its technical simplicity and transparency. Here, we present a new Python-based application that combines the benefits of automation and expert judgement using a semi-automated approach. CYCLIM first detects cycle boundaries using a matched filtering approach before then allowing the user to inspect and refine the output. Additionally, CYCLIM estimates age uncertainty via a noise-based Monte Carlo approach and can incorporate additional chronological ties (e.g., radiocarbon or U-series). We demonstrate CYCLIM’s effectiveness using a previously published palaeoclimate reconstruction and show its additional features, without knowledge of the original age model. In this example CYCLIM found 94.4% of the cycles automatically and required a manual tuning of ~9 cycles per 100. The final age model shows strong agreement with the published record with a mean absolute deviation of 0.79 years.
How to cite: Baldini, J. and Forman, E.: CYCLIM: semi-automated cycle counting for robust age model generation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10406, https://doi.org/10.5194/egusphere-egu26-10406, 2026.
Changes in ocean ventilation have been pivotal in regulating carbon sequestration and release on centennial to millennial timescales. However, paleoceanographic reconstructions documenting changes in deep-ocean ventilation using 14C dating, may bear multidimensional explanations, obfuscating the roles of ocean ventilation played on climate evolution. Here, we show that previously inferred poorly ventilated conditions in the North Atlantic were linked to enhanced pre-aged organic carbon (OC) input during Heinrich Stadial 1 (HS1). The 14C age of sedimentary OC was approximately 13,345 ± 692 years older than the coeval foraminifera in the central North Atlantic during HS1, which is coupled to a ventilation age of 5,169 ± 660 years. Old OC was mainly of terrigenous origin and exported to the North Atlantic by ice-rafting. Remineralization of old terrigenous OC in the ocean may have contributed to, at least in part, the anomalously old ventilation ages reported for the high-latitude North Atlantic during HS1.
How to cite: Bao, R., Liu, J., Wang, Y., Jaccard, S. L., Wang, N., Gong, X., and Fang, N.: Pre-aged terrigenous organic carbon biases ocean ventilation-age reconstructions in the North Atlantic, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4682, https://doi.org/10.5194/egusphere-egu26-4682, 2026.
This study aims to establish the chronology of lower sediment deposition in Lake Żarnowieckie, a glacial-origin lake located in the coastal zone of the Baltic Sea in northern Poland, through radiocarbon dating. An 8-meter-long sediment core was extracted from the lake’s bottom. Then, 21 samples of the bulk sediment, as well as plant remains, were selected from the layers of visible lithological borders. The samples underwent ABA chemical preparation and were subsequently processed into graphite for analysis using the MICADAS accelerator mass spectrometer at the 14C and Mass Spectrometry Laboratory in Gliwice. A total of 20 dating results, ranging from 2,300 BP to near the limit of the radiocarbon method were obtained. Comparison of these results with expert palynological and lithological analyses indicated that 12 dates were overestimated due to the reservoir effect and redeposition of older material. The reservoir effect in Lake Żarnowieckie is estimated at several hundred to 2,000 years, consistent with findings from other Polish lakes. Two samples showed particularly large age discrepancies compared with the age-depth model, suggesting the possible redeposition of older material and sedimentation disturbances, such as sublacustrine landslides or increased erosion. Additionally, two samples (with ages approaching the radiocarbon method limit) originated from deep, sandy layers that were likely deposited by glacial processes before the formation of the lake. The remaining six dates were considered reliable and were subsequently used to construct the age–depth model. The sedimentation rates derived from the model vary distinctly between lithological units.
Research supported by EU funds FSD – 10.25, Development of Higher Education Focused on the Needs of the Green Economy, European Funds for Silesia 2021–2027: The modern methods of the monitoring of the level and isotopic composition of atmospheric CO2 (project no. FESL.10.25-IZ.01-06C9/23-00). This research was partially funded by the Polish Geological Institute, National Research Institute (Grant No. 62.9012.2309.00.0), and partly by the NCN Project, Opus 23 (UMO-2022/45/B/ST10/03167) and Opus 29 (2025/57/B/ST10/03700).
How to cite: Piotrowska, N., Kamińska, A., Błaszkiewicz, M., Hrynowiecka, A., Słowiński, M., Małka, A., and Kramkowski, M.: Radiocarbon dating of sediments from Lake Żarnowieckie (North Poland) , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10530, https://doi.org/10.5194/egusphere-egu26-10530, 2026.
Marine shells are commonly used for determination and correction of marine reservoir effect (MRE); however, their susceptibility to surface contamination makes sample treatment a critical step in obtaining reliable ¹⁴C results.
In this study, marine shells collected from living specimens of common cockle (Cerastoderma glaucum) from the Baltic Sea, were investigated as modern reference material for a ¹⁴C-based assessment of the marine reservoir effect. A series of preparation protocols was applied to evaluate the influence of different cleaning and CO2 extraction methods on radiocarbon measurements.
In the first stage, shell cleaning involved mechanical surface cleaning, ultrasonic bath treatment, and rinsing in hydrochloric acid (HCl). The aim of these procedures was to remove potential contaminants and algal material from the shell surface.
In the subsequent stage, carbon dioxide (CO2) was extracted from shell carbonate using different analytical approaches. These methods included dissolution of whole shells in orthophosphoric acid (H3PO4) under vacuum conditions, with sequential collection of CO2 fractions after 15 and 30 minutes of dissolution, as well as a final fraction obtained after complete dissolution of the material. In addition, CO2 was extracted from crushed shell material, by dissolution in orthophosphoric acid carried out in the presence of helium (He) atmosphere. Alongside the shell carbonate samples, algal material collected from the shell surfaces was also measured for radiocarbon content, to assess potential differences between coexisting carbon reservoirs.
The comparison of preparation and extraction methods provides insight into methodological factors affecting radiocarbon measurements of modern marine shells and contributes to improving the reliability of MRE determination in the Baltic Sea.
The participation of DJM, AM and NP in the EGU 2026 General Assembly was funded by the project EU funds FSD - 10.25 Development of higher education focused on the needs of the green economy European Funds for Silesia 2021-2027: The modern methods of the monitoring of the level and isotopic composition of atmospheric CO2 (project no. FESL.10.25-IZ.01-06C9/23-00).
How to cite: Michczynska, D. J., Michczyński, A., Piotrowska, N., Bolik-Głuszek, A., Kamińska, A., Borówka, R. K., Mainka, M., Wojcik, M., and Zakrzewska, Z.: ¹⁴C-based investigation of the marine reservoir effect using shells collected from living specimens of common cockle (Cerastoderma glaucum) from the Baltic Sea, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11851, https://doi.org/10.5194/egusphere-egu26-11851, 2026.
The compilation of regional radiocarbon datasets offers significant opportunities for advanced analyses and the formulation of broad-scale inferences regarding past environmental and climatic changes. In this study, we analyse a comprehensive dataset of radiocarbon dates obtained from mountain mires in the Sudetes, encompassing sites located in both Poland and Czechia. These mires represent valuable natural archives that often preserve continuous stratigraphic records of Holocene environmental and climatic variability.
We collected 237 radiocarbon dates from 61 mires. Our analysis concentrated on dates that came from the basal layers of the mires. These dates were calibrated and analyzed using a summed probability density function (PDF) to determine the periods favorable for the formation of mires. The results show that the timing of mire development varies depending on elevation, with higher areas generally hosting newer mires. This pattern is statistically significant and may suggest that older peat deposits at these elevations have been removed due to denudation, erosion, or intensified snow-related processes.
The initiation of peat accumulation generally corresponded with significant climatic transitions during the Late Glacial and Holocene periods, with several intervals marked by interruptions in mire development. Regardless of elevation, mire establishment was particularly associated with the 9.4 and 8.2 ka climatic events. In mires located below 1000 m a.s.l., enhanced initiation also coincided with the end of the Allerød, the onset of the Holocene, and the 11.8 ka event. In contrast, the 4.2 ka event is characterized by a pronounced hiatus in the formation of new peatlands, irrespective of altitude. Further periods less conducive to mire formation occurred at ages 11–10.2, 7.8–7.2, and 4.8–3.8 calibrated kBP.
The regional synthesis presented in this study highlights both the potential and the current limitations of radiocarbon-based reconstructions of mire development in the Sudetes.
The participation of Adam Michczyński in the EGU 2026 General Assembly was funded by the project EU funds FSD - 10.25 Development of higher education focused on the needs of the green economy European Funds for Silesia 2021-2027: The modern methods of the monitoring of the level and isotopic composition of atmospheric CO2 (project no. FESL.10.25-IZ.01-06C9/23-00).
How to cite: Michczyński, A. and the Sadzonki Team: Determination of periods favorable for the formation of mires in the Sudetes (SW Poland and N Czechia) based on the analysis of a set of radiocarbon dates, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13839, https://doi.org/10.5194/egusphere-egu26-13839, 2026.
Radiocarbon ages of bulk sedimentary organic carbon (bulk OC) are often used on continental shelf. However, bulk OC ¹⁴C ages can be older than those of co-deposited carbonates. We examined this issue using two mud-dominated sediment cores from the East Sea shelf area: HI-24-05 GPC1 from the Korea Strait Shelf Mud (KSSM) (water depth, 110 m) and 22HP-01 from the Hupo Basin (water depth, 204 m). We measured AMS ¹⁴C ages of planktonic foraminifera (Globigerinoides sacculifer). Then, they were compared with bulk OC ¹⁴C ages from the same or adjacent depth intervals. We also measured TOC, δ¹³CTOC, and TOC/TON. The sediments of two cores cover the Holocene (approximately 8 kyr BP). In both core records, ¹⁴C ages of bulk OC are consistently older than those of foraminiferal shell. Bulk OC ¹⁴C ages are ~800–1300 years older than those of foraminiferal carbonate. The offset is larger in the KSSM core than in the Hupo Basin core. In contrast, δ¹³CTOC (approximately −21‰) and TOC/TON (7–9) vary within narrow ranges. We evaluate several possibilities that may cause the carbonate–OC ¹⁴C offsets, including organic matter source, bioturbation, particle residence time, and sediment redistribution on the shelf. The results may provide practical criteria for diagnosing carbonate–OC offsets and help to use radiocarbon for precise age control of sedimentary sequence.
How to cite: Ko, T. W. and Lee, K. E.: Carbonate–organic ¹⁴C age offsets in the East Sea shelf sediment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15509, https://doi.org/10.5194/egusphere-egu26-15509, 2026.
The radiocarbon method remains the cornerstone of chronological frameworks in archaeology and human evolution. Yet, many pivotal questions, such as the timing of Homo sapiens’ dispersals and interactions with Neanderthals, have been constrained by methodological limitations, particularly during periods where the calibration curve offers low resolution. Recent innovations in radiocarbon pretreatment, AMS measurement precision, and the integration of high-resolution atmospheric datasets are transforming this landscape.
For instance, recent work on subfossil larch trees from Revine (Italy) [1] demonstrates the potential of sub-decadal tree-ring records to capture fine-scale atmospheric radiocarbon fluctuations during the glacial period. These datasets highlight not only the limitations of current calibration curves beyond 14,000 years BP but also point the way forward: developing calibration curves with the resolution necessary to meet the precision demands of archaeological research between 50,000 and 15,000 cal BP.
A prominent case study that benefits from such methodological advances is the reassessment of the chronology of the Initial Upper Palaeolithic (IUP) at the Bacho Kiro Cave site (Bulgaria)[2]. Here, over 20 radiocarbon dates, obtained from well-preserved human bones and associated faunal material, were analyzed from a single stratigraphic layer (N1-I). These dates, produced with rigorous collagen pretreatment and high-precision AMS, achieve error ranges as low as ±300 years at around 42,000 14C BP, a significant improvement over earlier generations of dating. By integrating these data with refined Bayesian models and an enhanced calibration curve that incorporates floating tree-ring chronologies, the site's timeline has been clarified into at least two, possibly three, temporally distinct human occupations. Notably, these refined chronologies align the occupations with specific climatic phases, revealing that Homo sapiens' presence at the site spanned both colder (Greenland Stadial 12) and warmer (Greenland Interstadial 11) periods. This climate-linked resolution underscores the adaptive capacity of early Homo sapiens and challenges earlier interpretations that assumed a single, continuous occupation, adding nuance to our understanding of their dispersal and settlement patterns in Europe.
Together, these methodological breakthroughs, high-precision dating, robust pretreatment, and improved calibration, are redefining our capacity to resolve the tempo of human evolutionary events. They pave the way for more nuanced narratives about human dispersal, cultural innovation, and interaction with changing climates across Eurasia. Looking forward, the integration of high-resolution radiocarbon data with paleoenvironmental and archaeological records holds the potential to transform our understanding of human resilience and decision-making in the face of rapid climate change during the Late Pleistocene.
How to cite: Talamo, S., Friedrich, M., Adolphi, F., Heaton, T. J., Kromer, B., Muscheler, R., Richards, M. P., Tassoni, L., and Wacker, L.: Breaking the Limits: Refining Human Evolution Timelines with High-RESOLUTION Radiocarbon Dating, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19856, https://doi.org/10.5194/egusphere-egu26-19856, 2026.
Trees are fundamental to human survival and progress, serving as essential resources throughout history. From early societies to modern civilizations, they have provided materials for shelter, tools, transportation, and fuel. The development of ancient societies was often closely tied to forests, which supplied wood for construction, shipbuilding, and daily implements. Beyond their practical uses, trees hold profound symbolic and spiritual significance in many cultures, representing life, wisdom, and resilience. Moreover, their preserved remains continue to shape historical and environmental research, offering invaluable insights into ancient timelines, climatic shifts, and human activity. Tree rings serve as natural archives of past environmental conditions, while their organic material provides a crucial foundation for radiocarbon dating, one of the most reliable methods for establishing absolute chronologies in archaeology. By analyzing the carbon isotopes in ancient wood, scientists can precisely date artifacts, settlements, and cultural transitions, refining our understanding of human history and the broader prehistoric world. A major challenge, however, is that radiocarbon dating is a destructive method, requiring the removal and chemical pre-treatment of a portion of the wood sample necessary for the 14C age determination. This process permanently alters or consumes the analyzed material, posing a significant dilemma for archaeologists, especially when working with rare or culturally significant wooden artifacts. Therefore, sampling must be minimized as much as possible while still ensuring accurate 14C measurement. To address this issue, this study explores the potential of Near Infrared (NIR) spectroscopy as a non-invasive diagnostic tool for assessing cellulose preservation in archaeological wood specimens before radiocarbon dating.
The Near-Infrared (NIR) technique was applied to a set of well-characterized archaeological wood samples covering a wide range of chronological periods, provenances, and depositional environments. Short-Wave Infrared (SWIR) hyperspectral data were acquired from the specimens and analyzed through a combination of qualitative spectral interpretation and chemometric methods, including Principal Component Analysis (PCA) and single-band spectral mapping.
Overall, the results indicate that NIR spectroscopy represents a rapid, reliable, and completely non-destructive approach for assessing the suitability of archaeological wood for radiocarbon dating. By guiding targeted and minimally invasive sampling, this method improves the efficiency and robustness of ¹⁴C analyses while reducing unnecessary material loss. The proposed workflow contributes to more sustainable radiocarbon practices and aligns analytical requirements with the principles of cultural heritage preservation. Furthermore, the integration of hyperspectral imaging and chemometric analysis offers promising perspectives for broader applications in archaeological science and conservation, including the non-invasive characterization and monitoring of wooden cultural heritage objects.
How to cite: Casaccia, N., Gatti, L., Carriero, N., Friedrich, M., Prati, S., Schmidt, M., Sciutto, G., Tassoni, L., and Talamo, S.: Balancing chronology and conservation: Near-Infrared spectroscopy for cellulose assessment in archaeological wood, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21019, https://doi.org/10.5194/egusphere-egu26-21019, 2026.
A new composite sediment core (OSS 21) was recovered in summer 2021 from the Ossówka palaeolake sediment succession (eastern Poland), close to earlier key drill sites. Three parallel boreholes with overlapping segments were correlated to establish a 53.98 m long composite sequence. This study focuses on the interval between 34.30 and 53.98 m, which includes the transition from the Elsterian Glacial (MIS 12) into the Holsteinian Interglacial (MIS 11c). Core handling included splitting, detailed macroscopic logging, targeted thin-section microfacies analysis, and high-resolution XRF core scanning combined with hierarchical cluster analysis and principal component analysis to summarize compositional variability and support facies interpretation.
Five sedimentological units (I–V) are distinguished and broadly corroborated by the XRF-based clustering. Basal unit I comprises structureless sandy–clayey material with scattered coarse sand and gravel, interpreted as Elsterian till. Unit II consists of laminated clayey silt with frequent fine sand layers and retains a siliciclastic geochemical signature (high Si–K–Ti; low Ca and organic-related signals). A major shift occurs at the onset of unit III, where carbonate mud with reduced siliciclastic input and increased endogenic components appears. Unit III is subdivided into IIIa (faint cm-scale lamination) and IIIb (more distinct sub-mm lamination) with pronounced sulfur variability and mixed “organic” cluster dominance.
Unit IV contains distinctly varved Holsteinian carbonate mud with near-continuous sub-mm light–dark couplets (average couplet thickness ~0.75 mm). Thin sections show light laminae dominated by micritic calcite and darker laminae enriched in organic matter and clay. Geochemically, carbonate associated elements Ca and Sr gradually increase through unit IV, which is consistent with CaCO₃ concentrations that increase from ~50% to ~65–70% while TOC decreases about ~2–3%. Unit V continues as laminated carbonate mud with generally weaker varve expression and further carbonate enrichment (CaCO₃ up to ~81% in the analyzed part). Together, OSS 21 provides a refined sedimentological and geochemical framework for future high-resolution palaeoenvironmental reconstructions of the Holsteinian, including potential investigation of intra-interglacial variability.
This research is funded as part of the NCN project “Novel multi-proxy approaches for synchronization of European palaeoclimate records from the Holstein Interglacial”, funded by the Polish National Science Centre through grant no. 2019/34/E/ST10/00275.
How to cite: Słowiński, M., Lauterbach, S., Tjallingii, R., Brauer, A., Gruszczyńska, A., Nitychoruk, J., Obremska, M., Polkowski, T., Rach, O., Sachse, D., Halaś, A., and Błaszkiewicz, M.: A new composite core from the Ossówka palaeolake (eastern Poland): sedimentary facies and XRF-based stratigraphy across MIS 12–11c, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22479, https://doi.org/10.5194/egusphere-egu26-22479, 2026.
The Holsteinian interglacial (terrestrial equivalent of MIS 11c in central Europe) is often viewed as a long (~15–16 ka), warm and humid interval formed under an orbital configuration comparable to the Holocene, with global temperatures ~1.5–2°C above pre-industrial levels (Koutsodendris et al., 2012; Kühl & Litt, 2007). High-resolution varved records show, however, that it was punctuated by two major oscillations: the Older (OHO) and Younger Holsteinian Oscillation (YHO) (Koutsodendris et al., 2012). Here, we assess lake ecosystem responses to the YHO using an exceptionally well-preserved Cladocera record.
A 54 m sediment core from Ossówka (eastern Poland) preserves the Holsteinian interval in partially laminated, carbonate-rich lacustrine deposits. The interglacial and the position of the oscillations were constrained by high-resolution pollen analysis (1–2.5 cm), providing the stratigraphic framework for proxy interpretation. Although Cladocera analysis is widely used to infer trophic state, water depth, and habitat structure, it is rarely applied to sediments older than MIS 3 due to poor preservation of chitinous remains. At Ossówka, preservation is outstanding, including delicate planktonic Daphnia remains. We identified in total 29 cladocera taxa; species richness ranges from 8 to 16 and total abundance from 1,700 to 8,600 specimens/cm⁻³.
The high-quality material enables a high-resolution reconstruction of ecosystem change across the YHO based on taxonomic composition, complemented by ephippia production as an indicator of ecological stress. Continuous Daphnia spp. occurrence also permits morphometric measurements of the postabdominal claw as a body-size metric potentially linked to temperature variability.
This research has been supported by the Narodowe Centrum Nauki (National Science Center) (grant. no. 2019/34/E/ST10/00275).
Koutsodendris, A., Lotter, A.F., Kirilova, E., Verhagen, F.T.M., Brauer, A. and Pross, J. (2013), Evolution of a 12-ka-long Holsteinian (MIS 11c) palaeolake. Boreas, 42: 714-728. https://doi.org/10.1111/bor.12001
How to cite: Suchora, M., Obremska, M., Lauetrbach, S., Błaszkiewicz, M., Brauer, A., Gruszczyńska, A., Polkowski, T., Hałaś, A., Tjallingii, R., Nitychoruk, J., and Słowiński, M.: Tracking the Younger Holsteinian Oscillation in laminated lake sediments of Holsteinian (Mazovian) interglacial (MIS11c). Cladocera evidence from Ossówka (E Poland), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23180, https://doi.org/10.5194/egusphere-egu26-23180, 2026.
Radiocarbon dating is an essential tool in paleo and environmental studies. The selection of a suitable sample and its preparation for radiocarbon dating are key steps that affect the accuracy and precision of the results. Proper preparation allows the elimination of impurities that, by distorting the carbon isotope ratio, could lead to errors in determining the sample's actual age. Different purification procedures and modifications are applied depending on the type of sample being subjected to radiocarbon dating. Each material type requires an individual approach, considering its properties, state of preservation, and potential sources of contamination. Close collaboration among researchers in the application fields of 14C (archaeologists and earth scientists) is vital from the first step of sample selection. University-based 14C preparation laboratories focusing on selecting and treating suitable 14C material can facilitate such interdisciplinary exchange. Moreover, 14C laboratories located at universities can help educate the next generation of geochronologists.
In the past 2 years, a new preparation laboratory has been established at Maria Curie-Skłodowska University (UMCS) in the Ecotech-Complex in Lublin. The first sediment samples, peat, wood, and charcoal, were separated and successfully analysed at the ETH AMS facility in Zurich. Our laboratory is equipped to prepare all macroscopic samples and follows the sample selection procedures described by Hajdas et al. (2024).
Selected, well-defined samples undergo standard chemical treatment. The primary purification procedure for organic samples is the ABA (Acid-Base-Acid) procedure. It involves successive acid and base treatments at elevated temperatures to remove carbonates and humic substances, followed by a final acid treatment to neutralize the sample. The basic procedure is often modified to the specific sample being analyzed, for example, by lowering temperatures and reducing contact time for samples with poorly preserved structures. At this stage, treating the sample with alkali also enables the separation of humic acids, which can then be analyzed for ¹⁴C.
The clean, dry samples are weighed (approximately 1 mg of C) and transferred to the AMS laboratory. At this point, if the clean samples are very small, an additional material sample can be prepared, or samples containing less than 100 μg of carbon can be measured using a Gas Ion Source (GIS) (Ruff et al., 2010). Secondary standards and blanks are prepared alongside the ‘unknown’ samples. This paper reports the first results obtained from samples prepared in the LBC14 laboratory.
References
Hajdas, I., Guidobaldi, G., Haghipour, N., and Wyss, K. 2024. Sample Selection, Characterization and Choice of Treatment for Accurate Radiocarbon Analysis—Insights from the ETH Laboratory. Radiocarbon 66(5):1152-1165. doi:10.1017/RDC.2024.12
Ruff, M., Fahrni, S., Gaggeler, H. W., Hajdas, I., Suter, M., Synal, H. A., Szidat, S., and Wacker, L., 2010, On-Line Radiocarbon Measurements of Small Samples Using Elemental Analyzer and Micadas Gas Ion Source: Radiocarbon, v. 52, no. 4, p. 1645-1656.
How to cite: Hajdas, I., Burdzy, K., Suchora, M., Lehmann-Konera, S., Pietruczuk, J., Pidek, I. A., Dobrowolski, R., Maziarczuk, M., Łuczkiewicz, P., Haghipour, N., and Ramsperger, U.: A support for geochronological studies—a new 14C sample treatment laboratory at the Maria Curie-Sklodowska University, Lublin, PL, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14575, https://doi.org/10.5194/egusphere-egu26-14575, 2026.
