Orals: Mon, 28 Apr | Room 0.31/32
Past climate and environmental changes can be reconstructed using paleoclimate archives such as ice cores, lake and marine sediment cores, speleothems, tree rings and corals. The dating of these natural archives is crucial for deciphering the temporal sequence of events and rates of change during past climate changes. It is also essential to provide quantified estimates of the absolute and relative errors associated with the inferred chronologies. However, this task is complex since it involves combining different dating approaches at different paleoclimatic sites and often on different types of archives. Here we present Paleochrono-1.1, a new probabilistic model to derive a common and optimised chronology for several paleoclimatic sites with potentially different types of archives. Paleochrono-1.1 is based on the inversion of an archiving model: a varying deposition rate (also named growth rate, sedimentation rate or accumulation rate) and also, for ice cores, a lock-in-depth of air (since, in the absence of significant surface melt, the air is trapped in the ice at about 50-120 m below the surface) and a thinning function (since glacier ice undergoes flow). Paleochrono-1.1 integrates several types of chronological information: prior knowledge of the archiving process, independently dated horizons, depth intervals of known duration, undated stratigraphic links between records, and, for ice cores, Δdepth observations (depth differences between events recorded synchronously in the gas and solid phases of a certain core). The optimization is formulated as a least-squares problem, assuming that all probability densities are near-Gaussian and that the model is nearly linear in the vicinity of the best solution. Paleochrono-1.1 is the successor of IceChrono, which produces common and optimized chronologies for ice-cores. Paleochrono-1.1 outperforms IceChrono in terms of computational efficiency, ease of use, and accuracy. We demonstrate the ability of Paleochrono-1.1 in an experiment involving only the MSL speleothem in Hulu Cave (China) and compare the resulting age model with the SISALv2 age models. We then demonstrate the multi-archive capabilities of Paleochrono in a new ice-core–speleothem dating experiment, which combines the Antarctic Ice Core Chronology 2023 dating experiment, based on records from five polar ice cores, with data from two speleothems from Hulu Cave dated using uranium/thorium radiometric techniques. We analyse the performance of Paleochrono-1.1 in terms of computing time and memory usage in various dating experiments. Paleochrono-1.1 is freely available under the MIT open-source license.
How to cite: Parrenin, F., Marie, B., Christo, B., Emilie, C., Ellen, C., Drysdale, R., Kawamura, K., Landais, A., Mulvaney, R., Oyabu, I., and Rasmussen, S.: The Paleochrono-1.1 probabilistic model to derive a common age model for several paleoclimatic sites using absolute and relative dating constraints, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6728, https://doi.org/10.5194/egusphere-egu25-6728, 2025.
This study details the construction of an age-depth model for the uppermost 128 meters of the 600 m long Acıgöl2009-B03 sediment core, retrieved from hypersaline Lake Acıgöl in southwestern Anatolia. The model matches the arboreal pollen record from Acıgöl2009-B03 with the LR04 benthic δ18O stack marine oxygen isotope record. Initial correlation employs the Dynamic Time Warping algorithm, refined through manual tuning. Validation of the model's accuracy incorporates multiple chronological constraints, including three radiocarbon dates, three U/Th dates, and the Kos Plateau Tuff, dated at 161.3 ± 0.1 ka. According to this model, the upper 128 meters of the Acıgöl2009-B03 sequence spans approximately the last 487,000 years, encompassing Marine Isotope Stages (MIS) 1 to 12 and part of MIS 13. Our model serves as an update to the previously published, linearly constructed, age model as being used more anchor point and an efficient algorithm for similarity measurements which lies on a robust statistical foundation. In this period, arboreal pollen data suggest increasing (decreasing) arboreal vegetation input during interglacial (glacial) periods.
How to cite: Çaldırak, H., Ön, Z. B., Akkiraz, S., Çağatay, M. N., Ghaleb, B., Wulf, S., Eriş, K. K., Acar, D., Kaiser, J., and Akçer Ön, S.: Chronology and environmental changes from a sediment core spanning the last 487 kafrom Lake Acıgöl (SW Anatolia), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1998, https://doi.org/10.5194/egusphere-egu25-1998, 2025.
While highly desired, it remains a challenge for luminescence dating to determine high doses, hence high ages (e.g., >300 ka). The challenge is to project a natural dose close to saturation to a dose-response curve generated with high laboratory doses. The single saturating exponential (SSE) function mostly delivers poor fits to this type of dose responses. Other functions, e.g., the single saturating exponential plus linear function, are then often employed, but these include constants that have no direct physical meaning. Such an approach is inconsistent with the OSL/IRSL measurement parameters (e.g. detection wavelength) by which the signal from a dosimeter’s specific trap-hole pair is targeted out of a broad light spectrum. It is therefore beneficial to employ a physically based model that allows to interpret observations obtained from high laboratory dose responses.
Here we employ the analytical expression, Lambert W, developed by Pagonis et al. (2020) which is an exact solution of the well-studied OTOR (one trap one recombination centre) model, and extended by Lawless and Timar-Gabor (2024) to the OTORX model. We compare results obtained from SSE fits, in particular the characteristic saturation dose (“D0”) parameter, with those obtained from the OTOR(X) functions. Well-bleached fine-grained polymineral samples irradiated up to ~5000 Gy were used and measured using the pIRIR225 protocol.
For the SSE function the results point to the 80% rule of thumb: at ca 80% of the saturation dose the SSE-fitted dose response tend to underestimate the natural dose. The OTOR(X) functions reveal that this is due to the ratio of trapping rate versus recombination rate of free electrons which changes as the regenerated dose response approaches saturation. Consequently, the shape of the dose response curve flattens out in a way that the SSE function is unable to predict. We show here how the change of shape affects the dose interpolation point and how the accuracy of dose estimate is tested using the 63% (D0) and 80% dose values. We conclude that the OTOR(X) functions provide accurate estimates of natural doses close to saturation.
How to cite: Mauz, B., Kreutzer, S., and Lawless, J. L.: Using OTOR(X) fit functions to improve estimation of high natural luminescence doses, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8761, https://doi.org/10.5194/egusphere-egu25-8761, 2025.
Abstract: The SAR-SGC method, integrating single aliquot regenerative (SAR) and standardised growth curve (SGC) protocols with advantages of saving machine measurement time. It has gained widespread application in recent years over diverse sediment types, including glacial, aeolian, fluvial, lacustrine, deltaic, and marine sediments. The method constructs inter-aliquot SGCs using conventional SAR measurements and determines SGC Des by inserting the LN/TN values of additional aliquots into the SGC. The final SAR-SGC De is obtained by calculating the arithmetic mean of the SAR Des and SGC Des. However, the optimal number of SAR and SGC aliquots for reducing machine time while retaining precision, is still ambiguous. To address this issue, we systematically investigated how varying the number of SAR aliquots and additional LN/TN measurements influences the stability and consistency of equivalent dose derived from SAR-SGC method with SAR protocol. We examined the minimal SAR-SGC combinations for three samples (JNZK01-G09, MW10-G16 and XBG06-G07, with an equivalent dose of ~44 Gy (with largest scatter in inter-aliquot SAR growth curves), ~46Gy and ~55Gy (with marginal scatter in inter-aliquot SAR growth curves) in the lower Yellow River plain, utilizing a Risø TL/OSL-DA-20 reader with a 90Sr/90Y beta source. Through extensive statistical evaluations, SAR-SGC estimation of the equivalent dose obtained with differing aliquot combinations shows that equivalent dose could be accurately estimated within acceptable uncertainty (<10%) using 6–15 SAR aliquots and additional 12–30 LN/TN aliquots. For samples with dispersed growth curves, we recommend a minimum of 6 SAR and 12 LN/TN aliquots for reliable age determination. And samples with concentrated growth curves may suffice with 4 SAR and 10 LN/TN aliquots. This study demonstrates that the combined SAR-SGC method significantly reduces machine time (at least 70%) compared to the SAR protocol alone while maintaining acceptable precision. These findings provide valuable guidance for luminescence dating laboratories and researchers in optimizing instrument usage under time constraints.
Key words: SAR-SGC method; Standardized growth curve; Single aliquot regenerative protocol; Equivalent dose; Luminescence dating; Statistical analysis; Machine time optimization
How to cite: Zhou, X., Liu, Y., Feng, X., and Lai, Z.: Performance of SAR-SGC method for equivalent dose determination of quartz OSL, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15342, https://doi.org/10.5194/egusphere-egu25-15342, 2025.
Dikes are among the most significant ancient human-made earthworks for flood control, land reclamation, and water management for millennia. However, determining the age of dike construction and development based on traditional dating methods (e.g., historical documents, archaeological find materials, and radiocarbon dating), is challenging, due to the paucity of materials and historical records. Luminescence dating may provide an alternative as it uses ubiquitous quartz or feldspar minerals to directly determine the burial age of sediments. In this study, we applied quartz optically stimulated luminescence (OSL) and feldspar single-grain post-infrared infrared stimulated luminescence (pIRIR) dating on two dikes: the Waal dike (near Wolferen-Sprok) in the Netherlands and the Scheldt dike (near Bornem) in Belgium. Our results confirm that luminescence dating provides reliable age estimates, consistent with other independent proxy data such as radiocarbon dating, archaeological artifacts, and historical evidence, and may refine site chronologies. Based on the age results, the history of dike construction and evolution was reconstructed. Additionally, the well-reset OSL signals for dike-related sediments suggest that fresh flood deposits were used for construction. This study highlights the potential of luminescence dating as a robust tool for reconstructing the history of dike construction and understanding ancient engineering.
How to cite: Huang, C., van Beek, R., Chamberlain, E., Wallinga, J., Moree, J., Cruz, F., Laloo, P., and Norde, E.: Reconstructing dike history using luminescence dating, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4772, https://doi.org/10.5194/egusphere-egu25-4772, 2025.
The chronology of Late Glacial and Early Holocene dune formation and wildfire activity at the Łaskarzew site, eastern Poland, was established using AMS radiocarbon (14C) and optically stimulated luminescence (OSL) dating. Situated within the European Sand Belt, the profile preserves 13 aeolian-soil cycles characterised by alternating phases of aeolian deposition, soil formation, and wildfire episodes, demonstrating the dynamic response of aeolian systems to short-term climatic oscillations. A total of 26 charcoal samples, collected from palaeosols and charcoal layers, were radiocarbon-dated, and cross-referenced with OSL ages of quartz grains, resulting in a robust chronological framework. Dune formation began during the Oldest Dryas, with intensified aeolian activity and four wildfire events recorded during the Allerød interstadial, a period marked by rapid vegetation regeneration and recurring fire episodes. The absence of Younger Dryas sediments reflects extreme environmental conditions, including aridity, limited vegetation, and intensified aeolian erosion. The Holocene sequence, enriched with charcoal-rich deposits, records nine independent wildfire episodes over approximately 4500 years, linked to warm climatic conditions that favoured the expansion of fire-prone pine forests and shaped dune environments. Aeolian activity persisted through this period, accumulating approximately three metres of sediment, before ceasing around 7 ka BP as vegetation stabilised the landscape. The integration of radiocarbon and luminescence dating techniques provided a detailed Late Quaternary chronology, offering valuable insights into the interplay of fire, vegetation, and aeolian processes within the European Sand Belt.
How to cite: Piotrowska, N., Moska, P., Sokołowski, R. J., Poręba, G., Zieliński, P., Mroczek, P., Łopuch, M., Jary, Z., Ustrzycka, A., Wojtalak, A., Szymak, A., Tudyka, K., Raczyk, J., Krawczyk, M., Adamiec, G., and Skurzyński, J.: Reconstructing Late Glacial–Early Holocene dune formation and wildfire dynamics using radiocarbon and OSL dating: Łaskarzew, Poland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12582, https://doi.org/10.5194/egusphere-egu25-12582, 2025.
Surface and buried paleosols are a significant archive of information about environmental change and are widely used in paleogeographic reconstructions. Soil features and their profiles change over time as a result of environmental change. The soil memory is the palimpsest-like, as opposed to the book-like, sedimentary record (Targulian and Goryachkin, 2004). The palimpsest-like memory of the soil requires informed and well-adapted strategies for deciphering and interpreting the information it contains. The question of soil age and its synchronization with reconstructed events remains one of the most controversial issues in paleosol interpretations. The complexity of the interpretation of obtained radiocarbon dates is related to the heterogeneous and heterochronous of soil organic matter (SOM). At present, there are many approaches to dating SOM, but for the paleosol for paleogeographic reconstructions, 14C dating is most often performed on total organic carbon (bulk carbon). This choice of dating fraction is usually related to the poor preservation of SOM and its low carbon concentration in paleosols. Dates obtained for SOM in buried soils are based on the assumption that SOM was formed "in situ". However, due to various natural processes, paleosols can contain carbon from a number of potential sources.
For buried soils formed in periglacial landscapes, a significant source of carbon is the supraglacial material: cryoconites and other organo-mineral formations that form on the surface and in the body of the glacier and enter the landscape during glacial melting. Our studies on glaciers and in periglacial landscapes of different natural zones (Svalbard, Franz Josef Land Archipelago, Polar Urals, Altai, Kamchatka) have shown that supraglacial material can have a radiocarbon age ranging from modern to very ancient (several thousand, sometimes tens of thousands of years). The largest dataset we have obtained for supraglacial objects is represented by carbon pools aged 1000 to 10,000 radiocarbon years, BP and >10,000 radiocarbon years, BP. The pool with an age of >10,000 radiocarbon years is associated with the presence of a "dead carbon" source near the studied glacier. Dates in the range of 10,000-20,000 radiocarbon years may also reflect the age of soils and sediments formed during the last deglaciation and buried within the body of the glacier as it advanced. Soils formed in the periglacial zone inherit the isotopic composition of SOM from supraglacial material and become carriers of "apparent" / inherited 14C age. The presence of cryoconite material in buried paleosols can be diagnosed by studying their micromorphology and identifying morphological structures characteristic of cryoconites. We have shown this for soils formed on cryoconite material in Svalbard and for lenses of buried fine-grained material in marginal glacial formations (Keiva) on the Koly Peninsula. When 14C dating paleosol series (traditional paleoarchives are studied in foothills and mountainous areas), it is necessary to consider the ice-carbon contribution to SOM in order to make correct paleo-reconstruction.
How to cite: Zazovskaya, E., Mergelov, N., Dolgikh, A., Turchinskaia, S., Dobryanskiy, A., and Bronnikova, M.: “Ice carbon” as a possible source of apparent age in paleosol dating, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14514, https://doi.org/10.5194/egusphere-egu25-14514, 2025.
We use in-situ cosmogenic 10Be in an attempt to date the construction of the Kalasasaya Platform temple at the UNESCO Heritage archaeological site at the ancient city of Tiwanaku, Bolivia. The unique site is located within the altiplano valley of Tiwanaku at 3870 masl near the southern shores of Lake Titicaca. The monuments at Tiwanaku were constructed as ceremonial and civic buildings of exceptional precision and quality by an Andean civilization, who were precursors of the Inca Empire. The date of construction of Tiwanaku is unknown. Earliest settlement is believed to be at least ~3,000 years ago and archeological evidence supports a drought-based empire collapse in the first half of the 12th century. Radiocarbon dating of construction material and other debris range from 300 to 950 AD (ie 1700 to 1050 years ago). At its apogee Tiwanaku is estimated to have extended over an area of as much as 6km2 and to have housed between 70,000 and 125,000 inhabitants.We gained permission to sample the very tops of 3 of the Kalasasaya pillars, and multi-meter sized excavated sandstone blocks and adjacent unmodified bedrock outcrop at a known quarry site which was used for sourcing material for Tiwanaku construction. The pillars, ~5 meters tall and of square meter section, frame the outer perimeter wall of the 120m square Kalasasaya Platform and are made of andesite and sandstone. Samples at the quarry site, about 15 km distant and at 4300 masl, were taken from surfaces of the cavity from where blocks originated, select faces from the extracted blocks and unmodified bedrock outcrop. We were able to re-orient extracted blocks back into their original excavated cavity and thus determine pre-excavated buried and post-excavated exposed faces which allowed us to measure how long ago the block was carved out of bedrock and rotated in the process. Our results show that the cosmogenic signal in platform pillar tops is dominated by inheritance but that blocks had been quarried as recently as 1500-3000 tears ago, the age range depending on choice of attenuation length and estimating shielding. Details of sampling, site descriptions and 10Be-age calculations will be presented.
How to cite: Fink, D., Levchenko, V., and Fujioka, T.: Cosmogenic exposure dating the Pre-Columbian archaeological structures at Tiwanaku, Bolivia , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5262, https://doi.org/10.5194/egusphere-egu25-5262, 2025.
U-Th geochronology is a key tool in Quaternary geology, widely applied to carbonate matrices with significant advancements achieved through MC-ICP-MS technology. However, 230Th dating remains challenging for samples with low-uranium concentrations and high-detrital thorium content which often reflecting open-system behavior. These factors increase uncertainties in age calculations. This study introduces an optimized U-Th dating methodology that integrates refined wet chemistry protocols and 10¹³-ohm amplifiers, significantly reducing expanded uncertainties.
The study employs a four-step validation process: i) testing 10¹³-ohm amplifiers using the NBL U-reference material (CRM 112A), and Th-reference material (IRMM035) of IRMM, ii) application to low-U (10–15 ppb) speleothem samples from the Cueva Fantasma (Atapuerca paleontological-archeological site, Burgos, Spain), iii) analysis of open-system shell samples from Turkey, iv) analysis of the internal speleothem standard (BSS2) of CENIEH.
Initial results using CRM 112A and IRMM035 reveal a tenfold improvement in signal-to-noise ratios with the 10¹³-ohm amplifiers. This configuration enables the use of Faraday cups instead of SEM detectors for U and Th-standard analyses, even at very low intensities (0.002–0.007V), a critical improvement for minimizing uncertainty budgets during bracketing sequences in U-Th dating. Comparative analyses of real samples from Atapuerca, Turkey, and the CENIEH speleothem standard (BSS2) show that the refined methodology reduces U-Th age uncertainties from 2–3% to 0.5–1%.
Beyond improved precision for younger, low-U samples, the method reduces the required sample size from ~100-150 mg to 40–50 mg, substantially lowering the influence of detrital Th contamination. The broader significance of this optimized approach lies in its application to environmental reconstruction during the Quaternary, offering robust tools for deciphering climate archives, paleoenvironments, and archaeological contexts.
How to cite: Hasözbek, A., Pourmand, A., Sharifi, A., Isabel Ortega, A., Parés Casanova, J., Vallverdú Poch, J., and Constantin, S.: Optimized U-Th Chronometry for Carbonates Using MC-ICP-MS: Advancements in Precision and Applications, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6277, https://doi.org/10.5194/egusphere-egu25-6277, 2025.
We investigate the characteristics of low-temperature yellow stimulated luminescence (YSL), to compare its utility for dating with infrared stimulated luminescence (IRSL) stimulated at 50 °C (IR50), post-IR50 yellow stimulated luminescence (pIR-YSL) and pIRIR290. Altogether, eleven samples from a range of depositional environments and known ages were tested. Thermal stability, bleachability, dose recovery, fading tests and equivalent dose estimation were undertaken. The pIR-YSL signal is stable up to 150 °C but susceptible to thermal transfer at higher temperatures and both the pIR-YSL and YSL50 signals bleach out at a rate and extent that is similar to the IR50 signal. Dose recovery tests on four of the young intermediate samples illustrate that the pIR-YSL signal can be both recovered and fully reset. Fading tests show that all three signals suffer from significant fading and equivalent dose estimations of the saturated samples IR50, IR-YSL and YSL50 signals significantly underestimate relative to the pIRIR290 signal. Elevated temperature signal combinations are additionally evaluated with the aim of further understanding the effect of elevated temperatures on the fading rate and ultimately the utility of YSL signals for dating.
How to cite: Buchanan, G., Preusser, F., Fitzsimmons, K., and Lauer, T.: Progress exploring the characteristics of yellow stimulated luminescence on potassium feldspar , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-646, https://doi.org/10.5194/egusphere-egu25-646, 2025.
Luminescence dating has long been used for dating sediments both in geological as well as archaeological context. Following numerous advances in feldspar and quartz luminescence dating in recent decades, a new method for feldspar dating is currently under development: Infrared photoluminescence (IRPL) is a novel technique, which allows the direct and non-destructive measurement of luminescence emitted by trapped electrons in feldspars (Prasad et al., 2017). IRPL arises from radiative excited state to ground state relaxation of trapped electrons within the principal trap in feldspar.
IRPL measurements enable the investigation of two emissions, one at 880 nm and another one at 955 nm (Kumar et al., 2018, 2021). Whilst most research on IRPL has focussed on understanding the physical processes leading to the IRPL emission in feldspars, yet little is known with regard to the application of IRPL as a dating technique. We build upon a first measurement protocol for sediment dating developed by Kumar et al. (2021) and combine the IRPL measurements with a modified post-IR IRSL protocol (pIRIR225 with IR stimulation at 50°C, 90°C, 225°C), which allows a comparison of the IRPL signals with three IRSL signals. This integration of the IRPL measurements in a pIRIR protocol might possibly reduce fading to a negligible level due to the successive IRSL and IRPL measurement steps.
First promising results on loess samples with known (independent) age from the Balta Alba Kurgan loess-paleosol sequence in Romania (Scheidt et al., 2021) will be presented. We conducted dose recovery tests, bleaching experiments and equivalent dose measurements using different test doses and will show first results of fading measurements. The dose recovery tests are within 10% of unity for most of the measurements suggesting sufficient performance of our novel IRPL/pIRIR protocol. However, IRPL equivalent doses seem to slightly underestimate previously measured pIRIR290 equivalent doses. Possible reasons will be discussed within the EGU presentation.
References
Kumar, R., Kook, M., Murray, A.S. & Jain, M. (2021). Towards direct measurement of electrons in metastable states in K-feldspar: Do infrared-photoluminescence and radioluminescence probe the same trap? Radiation Measurements 120, P. 7-13.
Kumar, R., Kook, M., & Jain, M. (2021). Sediment dating using infrared photoluminescence. Quaternary Geochronology 62, 101147.
Prasad, A.K., Poolton, N.R.J., Kook, M. et al. (2017) Optical dating in a new light: A direct, non-destructive probe of trapped electrons. Sci Rep 7, 12097.
Scheidt, S., Berg, S., Hambach, U., Klasen, N., Pötter, S., Stolz, A., ... & Nett, J. J. (2021). Chronological assessment of the Balta Alba Kurgan loess-paleosol section (Romania)–a comparative study on different dating methods for a robust and precise age model. Frontiers in Earth Science, 8, 598448.
How to cite: Nett, J. J., Reimann, T., and Riedesel, S.: Luminescence dating of feldspar using a novel infra-red photoluminescence signal – first dating results from loess samples, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2273, https://doi.org/10.5194/egusphere-egu25-2273, 2025.
Fluvial depositional systems are critical for understanding the interplay between tectonics and climate. Accurately determining the ages of these formations is essential for exploring the spatial and temporal evolution of river deposits. In arid and semi-arid regions, these systems predominantly consist of coarse materials and cobbles. Traditional age determination methods often focus on well-sorted fine sediments, while dating poorly sorted cobble layers presents a significant challenge. Recently, optically stimulation luminescence (OSL) is increasingly are used to determine the burial age of rocks. This new method relies on resetting of the latent geological OSL signals with depth into the rock surface, and the re-accumulation of new signals after the burial (Sohbati et al.,2015).
This study aims to investigate buried cobbles from terrace and alluvial gravel profiles along the Maying River, located at the foothills of the Qilian Mountains. We will utilize a Risø Luminescence Imager, complemented by in-situ measurement techniques (Sellwood et al.,2022). This integrated methodology will enhance our understanding of luminescence signal bleaching characteristics on rock surfaces, allowing for the rapid and accurate selection of samples for age dating. This approach not only mitigates the limitations of cobble dating across millennial to hundred-thousand-year timescales, but also provides novel insights into the late Quaternary geomorphology and tectonic evolution of rivers at the front of the Qilian Mountains.
Key words: Rock surface luminescence dating, Risø Luminescence Imager, Buried age
References
- Sohbati, R., Murray, A.S., Porat, N., Jain, M., Avner, U., 2015. Age of a prehistoric “Rodedian” cult site constrained by sediment and rock surface luminescence dating techniques. Quat. Geochronol. 30, 90-99.
- Sellwood, E. L., Kook, M., Jain, M., 2022, A 2D imaging system for mapping luminescence-depth profiles for rock surface dating. Radiat. Meas. 150, 106697.
How to cite: Cui, F., Zhang, H., Liu, J., and Qin, J.: Rock Luminescence Dating Method for Studying the Temporal and Spatial Evolution of the Maying River, Qilian Mountains, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3717, https://doi.org/10.5194/egusphere-egu25-3717, 2025.
The Middle Palaeolithic site of Chez-Pinaud in Jonzac (SW France) provides an unparalleled insight into the hunting and butchering behaviour of Neanderthals from ~60 ka 1 ago. Excavations in the late 1990’s and early 2000’s uncovered a 6-meter sedimentary sequence comprising apparently alternating thin sterile layers and artefact-rich deposits, hosting densely packed accumulations of large ungulate bone fragments and lithics of the Quina Mousterian industry 2 . These periodic deposits suggest repeated occupation and abandonment of the site, where Neanderthals were not inhabiting for long periods. Despite these observations we are still limited in a obtaining a full occupational history of the site, predominantly due to limitations in existing dating methods.
In this study a novel sampling approach was applied to improve the chronological resolution of this site, combining high-resolution Optically stimulated luminescence (OSL) dating and Bayesian modelling. A 40 x 40 x 40 cm sediment block was removed from the main Quina-bearing layer (Layer 22 2). Under controlled orange light at the RenDaL OSL laboratory at Université de Rennes, the block was carefully excavated by scraping away sediment in horizontal layers. Coordinates of artefacts were recorded and samples for OSL dating were collected at ~1 cm intervals down the block. Single-grain quartz OSL data were analysed using the BayLum R package 3, incorporating Bayesian statistical modelling to reduce age uncertainties and to investigate the models capacity to handle OSL ages in close temporal and spatial distribution.
Our results indicate that the top of the section represents more modern deposits (~2 ka), which are void of bone fragments. These ages suggest sediment mixing from surface disturbances such as collapsing limestone or anthropogenic activities. Beyond this modern layer, two artefact-rich occupational layers separated by a thin sterile layer are identified through plotting the 3D distribution of the artefacts. The corresponding Bayesian ages for these layers vary between 58 – 80 ka, and do not increase linearly with depth and are thus difficult to correlate directly with the individual artefact bearing layers. These varying ages raise questions over dose rates when we consider the complexity of the heterogeneous sediments in the block. Continuing modelling will be conducted with BayLum as well as further investigation into the dose rate of the samples in attempts to further investigate and increase precision of the ages.
This work underscores the value of combining precise excavation methods with Bayesian analytical approaches for OSL data to construct precise chronologies, especially in important prehistoric archaeological contexts which host well preserved and challenging chronologies.
References:
1 Richter, D. et al. Thermoluminescence dates for the Middle Palaeolithic site of Chez-Pinaud Jonzac (France). Journal of Archaeological Science 40, 1176–1185 (2013).
2 Airvaux, J. & Soressi, M. Le site paléolithique de chez-Pinaud à Jonzac, Charente-Maritime. Prehistoire du Sud-Ouest 8, (2004).
3 Philippe, A., Guérin, G. & Kreutzer, S. BayLum - An R package for Bayesian analysis of OSL ages: An introduction. Quaternary Geochronology 49, 16–24 (2019).
How to cite: Sellwood, E., Malservet, H., and Guérin, G.: Investigating the cyclicity of Neanderthal occupations at Chez-Pinaud, SW France, using high-resolution OSL dating and Bayesian analysis., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12656, https://doi.org/10.5194/egusphere-egu25-12656, 2025.
The sedimentary units overlying the so-called ‘Falaise de la Mine d'Or’ on the South-East coast of Brittany (France) have been studied for decades to reconstruct the evolution of fossil fluvial valleys in Brittany during the Pliocene and Quaternary (Guillocheau et al., 1998; Menier et al., 2006). However, published numerical ages are insufficient to provide a precise age of each of the units described, whose chronology relies on correlations with ESR dating of fluvial sediments from the interior of Central Brittany (Laurent et al., 1996). Thanks to the cron-BRET Project of the MSCA-Bienvenüe Bretagne Programme carried out by the Geo-Ocean Laboratory of the Université de Bretagne Sud in collaboration with the Cosmogenic Nuclide Laboratory of the University of Cologne (Germany), it has been possible to date the lower unit (U1), mainly composed of quartzite gravels and pebbles. In situ 10Be and 26Al concentrations produced within the quartz of these clasts become controlled by differential rates of decay when shielded from production at the surface (Dunai, 2010). The fact that the sediments are buried under a sedimentary shield of more than three metres, allows for the calculation of a burial age from the concentration of 10Be and 26Al by using the isochron method (Balco and Rovey, 2008; Granger et al., 2022). Preliminary results provide numerical data that place the formation of this unit 2.72 ± 0.19 million years ago, at the Plio-Quaternary boundary. Our study also includes the dating of the upper unit (U3) mainly composed of sand-sized materials (90-2000 µm), by analysis of the optically stimulated luminescence (OSL) signal of quartz (Murray et al., 2021) at the RenDaL Luminescence Laboratory (Géosciences- Univ. Rennes). The calculation of the palaeodose using Bayesian procedures (BayLum; Philippe et al., 2019) and of the natural dose rate from high-resolution gamma spectrometry (HRGs) measurements provides a burial age range between 263 and 408 ky. These data will be complemented by the dating of the materials composing unit U2 by analysing the infrared stimulated luminescence signal (IRSL) of potassium feldspar to extend the available dates and the knowledge of the landscape evolution of this coastal area linked to glacioeustatic oscillations and neotectonics during the Pleistocene.
How to cite: Arce Chamorro, C., Sautter, B., Guérin, G., Guillocheau, F., Binnie, S., Dunai, T., and Menier, D.: Optically Stimulated Luminescence and in situ 10Be / 26Al cosmogenic dating of the Upper and Lower Units from ‘La Falaise de la Mine d'Or’ at Pénestin (SW Brittany, France) within the cron-BRET Project., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1384, https://doi.org/10.5194/egusphere-egu25-1384, 2025.
Continental sedimentary deposits are essential geological records for understanding landscape evolution over time. In this context, the “modern analog” approach is employed in the Andes-Amazon system to deepen the understanding of past changes and the factors influencing them. This methodology involves studying contemporary fluvial deposits using advanced techniques and methods to identify how natural processes shape the current landscape. The main objective of this study is to determine the spatial variability and environmental controls of the sediment provenance and the erosion rates in modern deposits of the Ucayali, Maranõn, Napo, Madre de Dios, Huallaga, and Solimões rivers in the Andes-Amazon fluvial system. This approach will involve luminescence sensitivity signatures of quartz and feldspar grains, which can indicate grain source and transport process; the latitudinal gradient of erosion rates using in situ cosmogenic nuclides; the relationship between sedimentary variability and tectonic, topographic, lithologic, and climatic controls using Geographic Information Systems (GIS). The new cosmogenic nuclide and luminescence data will be used together to evaluate the compatibility of these methods in analyzing sediment provenance and erosion rates. This comparison will assess whether these methods and approaches can be consistently integrated, contributing to a more comprehensive understanding of sedimentary and erosive processes in the Andes-Amazon fluvial system. (FAPESP #2023/16318-1)
How to cite: Brandino de Campos, G., Barbosa Leite Cruz, C., Emerich Souza, P., Luísa Souza Simões, A., Breda, C., Cassimiro Brito, R., Bookhagen, B., Oliveira Sawakuchi, A., and Nascimento Pupim, F.: Sediment provenance and erosion rates in the Andes-Amazon fluvial system: a study using luminescence and cosmogenic nuclides technics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12755, https://doi.org/10.5194/egusphere-egu25-12755, 2025.
Holocene sedimentary sequences lacking organic remnants or containing redeposited organic material pose a challenge for detailed chronological investigations, as radiocarbon dating is unsuitable. Optically stimulated luminescence (OSL) can be used instead, but high-resolution OSL is costly. A more cost-effective and efficient approach involves the combination of low-resolution OSL dating with portable OSL (pOSL) profiling in 5–10 cm increments (e.g. Sanderson and Murphy, 2010; Brill et al. 2016). This method has been employed in the analysis of cored lacustrine sedimentary sequences from the northern shore of Lake Schweriner See, Germany.
In well-bleached Holocene sediments, quartz equivalent doses and portable post-infrared blue-light stimulated luminescence signals (further pOSL) from the polymineral fraction are linearly correlated (e.g. Brill et al., 2016). We used the obtained linear functions to estimate equivalent doses (Des) in quartz for each pOSL signal. The dose rates were then interpolated between full OSL samples, and the ages were calculated by dividing the Des by the corresponding dose rates. Finally, both the quartz full OSL ages and the ages derived from the pOSL signals were incorporated into a Bayesian age-depth model to obtain a continuous chronology.
The pOSL-to-De ratio is also a useful tool in the identification of incompletely bleached samples. Poorly bleached sediments exhibit a higher pOSL-to-De ratio in comparison to well bleached sediments because pOSL is a composite of signals from quartz and feldspars, which require a greater exposure time for complete bleaching than OSL from pure quartz (e.g. Murray et al., 2012). In the littoral sequences studied, elevated pOSL-to-De ratios were found to correspond with high quartz Deoverdispersion (OD), which is another indicator of poor bleaching. One particular sample was observed to exhibit a high pOSL-to-De ratio yet low OD (15%), which may be attributed to distinct OSL sensitivity linked to a specific sediment source.
Our results demonstrate that the proposed approach suits littoral sediments and improves chronological frameworks for lacustrine sequences. A potential avenue for further refinement of age-depth models lies in the measurement of dose rates for all pOSL samples, as opposed to their estimation through interpolation.
References
Brill, D., Jankaew, K., & Brückner, H. (2016). Towards increasing the spatial resolution of luminescence chronologies – Portable luminescence reader measurements and standardized growth curves applied to a beach-ridge plain (Phra Thong, Thailand). Quaternary Geochronology, 36, 134–147.
Murray, A. S., Thomsen, K. J., Masuda, N., Buylaert, J.-P., & Jain, M. (2012). Identifying well-bleached quartz using the different bleaching rates of quartz and feldspar luminescence signals. Radiation Measurements, 47(9), 688–695.
Sanderson, D. C. W., & Murphy, S. (2010). Using simple portable OSL measurements and laboratory characterisation to help understand complex and heterogeneous sediment sequences for luminescence dating. Quaternary Geochronology, 5(2–3), 299–305.
How to cite: Ruchkin, M., Lorenz, S., Adolph, M.-L., and Haberzettl, T.: Applying portable OSL to obtain a detailed chronology of littoral sedimentary sequences from the northern shore of Lake Schweriner See, Germany, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21256, https://doi.org/10.5194/egusphere-egu25-21256, 2025.
We have studied the loess-palaeosol sequences of the Khovaling Loess Plateau in Tajikistan, which form the most complete record of subaerial sedimentation in Central Asia. Studied sections contain several layers with Early and Middle Palaeolithic tools, and therefore record some of the earliest events of hominin dispersal into Central Asia.
As part of a major NordForsk funded project ‘Timing and Ecology of the Human Occupation in Central Asia’ (THOCA; www.thoca.org), we applied high-resolution luminescence dating to the upper parts of three sections of Khovaling loess plateau (Khonako-II, Kuldara, and Obi-Mazar) in order to: (1) provide an independent timescale for palaeoclimatic studies; (2) assess the completeness of the sedimentary record; and (3) investigate the main stages of dust accumulation over this interval.
The luminescence chronology extends back to ~250 ka and reveals distinct erosional hiatuses ranging in duration from ~7 ka to a full glacial-interglacial cycle (~100 ka). Some of these breaks were not identifiable in the field. These discontinuities had not been previously recognized, potentially leading to significant errors in palaeosol identification and, consequently, in the presumed chronology. Now, we have a better understanding of the aeolian sedimentation in the region and the stages of loess/palaeosol formation. The new chronology provides a reliable correlation of regional features with global events and relates them to climate change, soil cover development, and the evolution of Early and Middle Paleolithic.
How to cite: Taratunina, N., Buylaert, J.-P., Challier, A., Murray, A., Sosin, P., and Kurbanov, R.: High resolution luminescence dating of the Khovaling Loess Plateau sites (Tajikistan), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13277, https://doi.org/10.5194/egusphere-egu25-13277, 2025.
Anthropogenic carbonates such as lime mortars and plasters have been receiving growing attention as they are an invaluable source of information for archaeologists, conservators, and restorers of cultural heritage. Taking into account the production process, the age of mortars reflects the age of the building. Two physical dating methods currently enable us to date mortars: radiocarbon (14C) dating and optically stimulated luminescence (OSL). Fast development in 14C and OSL mortar dating naturally widens the scope of performed analysis, and promotes the search for different methods which may be applied to these materials. In this study we present the analysis of historical lime mortars in order to assess the possibility of future dating by Electron Spin Resonance (ESR) spectroscopy. ESR dating has been applied to various geological and archaeological materials, but there are virtually no examples of dating carbonates younger than 10 000 years. Since carbonate crystals are formed during the mortar production, this moment can be regarded as the zero point for the accumulation of trapped charges, and their concentration in a measured sample should reflect the age of the mortar.
Our previous works on samples from Sveta Petka church in Budinjak, Croatia, and an ancient settlement Hippos, Israel, show the growth of signals related to the paramagnetic centres with the dose of laboratory radiation. However, in order to obtain the age of the samples the natural material should exhibit measurable ESR signals of the centres suitable for dating. In the relatively young (as far as ESR dating is concerned) materials the signals are very weak, however detailed analyses showed presence of such signals in several investigated mortar samples. In this work we investigate ESR signals in natural and laboratory-irradiated carbonate lime binders from several different archaeological sites, with ages ranging from about 2000 to 500 years old. The samples have been previously dated by 14C method, which means they had undergone extensive characterisation and preparation, ensuring the selection of binder, which reflects the true age of the mortar. We analyse the spectra with the aid of ESR simulations in order to identify the paramagnetic centres present in the samples, and compare them to the centres commonly found in carbonates and used for ESR dating. The goal of this work is a qualitative analysis of the natural signals found in a variety of mortars, assessing their potential suitability for ESR dating. This study is a first part of the ongoing project focused on establishing ESR as a method of dating anthropogenic carbonates in a form of lime mortars, and comprises the preliminary analysis of the subject, which will be followed by future in-depth studies.
How to cite: Kabacińska, Z. and Michalska, D.: Towards Electron Spin Resonance dating of anthropogenic carbonates: ESR signals of 14C-dated historical lime mortars, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13244, https://doi.org/10.5194/egusphere-egu25-13244, 2025.
Stone fish traps and weirs are the most common archaeological remains in fluvial and coastal environments. In Brittany, almost 800 of them were identified by Daire and Langouët (2014). Usually, these are made of numerous erected stones, that more or less precisely outline an alignment. Dating these remains represents a real archaeological issue, since stone fish traps have been raised for millennia, presumably from the early Neolithic to the Middle Ages. However, it is also a challenge as there is no organic matter preserved in the core of these structures.
In this presentation, we assess the age of fish weirs found in Brittany by comparing their altitude with the sea-level rise estimation curve since the last glaciation 20 000 years ago. A software named CHRONOE was developed in R in order to improve the reliability of the data, among which tidal curves (García-Artola et al. 2018). Statistical analysis – using the R package ArchaeoPhases (Philippe and Vibet 2020) – of the ages determined by CHRONOE for a corpus of diverse stone fishing weirs, identifies periods of intensification and rarefaction of fishing using such structures. Thus, it is possible to discuss the evolution of fishing practices in human societies along the coasts of Brittany.
This work is the first step of a PhD Thesis; it will be followed by direct dating of stone fish traps. Indeed, rock surface luminescence dating \autocite{soh12} has been shown to reliably estimate the last time a rock surface was exposed to light (Sohbati et al. 2012) has been shown to reliably estimate the last time a rock surface was exposed to light (Freiesleben et al. 2015). Therefore, it will be applied to a few of these structures, after careful selection based on their presumed age. The bottom surface of sampled rocks from fish weirs will be sampled for OSL intensity profiling and burial dating. The numerical absolute ages given by obtained with OSL will then be compared to those assessed with CHRONOE, to discuss the reliability of the underlying assumptions and refine the model. Eventually, CHRONOE may hold the potential to date any submerged object whose utility (or existence) is linked with the intertidal zone.
Keywords : geochronology, OSL, archaeology, fish weirs.
References
Daire, M.-Y., & Langouët, L. (2014). Se nourrir le long des côtes bretonnes : Réflexions à partir d'une analyse diachronique des barrages de pêcheries. Actes des congrès nationaux des sociétés historiques et scientifiques, 138 (2), 105133.
Freiesleben, T., et al. (2015). Mathematical model quantifies multiple daylight exposure and burial events for rock surfaces using luminescence dating. Radiation Measurements, 81, 1622.
García-Artola, A., et al. (2018). Holocene sea-level database from the atlantic coast of europe. Quaternary Science Reviews, 196, 177192.
Philippe, A., & Vibet, M.-A. (2020). Analysis of archaeological phases using the R package ArchaeoPhases. Journal of Statistical Software, 93, 125.
Sohbati, R., et al. (2012). Optically stimulated luminescence (OSL) as a chronometer for surface exposure dating. Journal of Geophysical Research: Solid Earth, 117, 2012JB009383.
How to cite: Jumaucourt, A., Guérin, G., Le Bris, D., Stephan, P., Bernier, I., and Pailler, Y.: A way to date stone fish weirs ? Some perspectives., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19154, https://doi.org/10.5194/egusphere-egu25-19154, 2025.
Lake sediments form a valuable and often continuous record for reconstructing past climate and the occurrence and impact of natural hazards. The interpretation of this record, however, relies heavily on a robust chronology formed by age-dating the sediments. For recent (i.e. Quaternary) lake sediments, radiocarbon dating of organic material is a fundamental dating technique. However, constructing a lake sediment chronology can be challenging, since the use of radiocarbon dating is dependent on many factors, including the type of material to be dated, depositional circumstances and possible contamination of 14C. Volcanogenic CO2, for instance, is depleted in 14C. This implies that in regions with surface exhalations of volcanic CO2 the concentration of 14C in the surrounding atmosphere is diluted. For this study, the effect of volcanogenic CO2 gas emissions on the use of radiocarbon dating was investigated in the Laacher See volcanic crater in western Germany. This crater was formed after the eruption of the Laacher See Volcano around 13 ka BP. It contains multiple degassing vents emitting CO2 of magmatic origin, in the form of underwater bubble seeps in the lake (“wet mofettes”) and onshore soil degassing (“dry mofettes”). Living plant material, i.e. leaves of Taraxacum genus plants, were sampled in several locations in the crater and dated to examine their range in radiocarbon ages and spatial variability. Additionally, a > 4 m long sediment core taken in the lake was sampled for organic material and bulk sediment to assess the offset of radiocarbon ages to their true or expected ages. Our results show that all dated samples exceed their true or expected ages, with the Taraxacum samples giving variable radiocarbon ages of up to 9000 a BP. Along a transect of sampled Taraxacum plants, the radiocarbon ages decrease with an increasing distance from the degassing vents along the lake shore. The radiocarbon ages of the sediment core samples show that organic material deposited in the lake is also affected by volcanogenic CO2 emissions, with some radiocarbon ages exceeding the age of the Laacher See eruption that formed the crater, although no regular offset could be determined for these samples with regard to their depth in the core. Furthermore, the radiocarbon ages do not correspond to a 210Pb/137Cs age-depth model that was established for the top of the core. Radiocarbon dating is shown to not provide reliable results for establishing a chronology for the sedimentary infill of Laacher See. Further research is required to better understand the influence of volcanogenic CO2 on organic material, such as effects of temporal and spatial variations in CO2 flux. In the case of Laacher See, other age-dating techniques should be considered to establish an age-depth model with reliable, non-14C dependent ages.
How to cite: Claeys, L., Albers, S., Hajdas, I., and De Batist, M.: Volcanogenic CO2 emissions affect radiocarbon dating in a case study from the Laacher See crater lake, Germany, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1725, https://doi.org/10.5194/egusphere-egu25-1725, 2025.
Since the 19th century, various authors have assigned the glacial landforms in the lower valleys of northern Italy to different ice ages (Penck and Brückner 1909). This study was part of a project that involved a broad geomorphological analysis and the first-time absolute in-situ exposure dating of erratic boulders using 10Be and 36Cl (Braakhekke et al. 2020). In addition to the cosmogenic analysis, seven radiocarbon samples were taken from a fluvial terrace outcropping 6 meters high along the Ticino River. Where possible, the samples were sieved to separate a bulk fraction (<125 μm) from the undefined organic fragments. Some samples were partly dissolved during the subsequent ABA preparation of all fractions. This way, we obtained up to four ages per initial sample: one each for the insoluble bulk fraction, the humic acid of the bulk, the organic fragments, and the humic acid of the organic fragments. The obtained radiocarbon ages vary significantly, with the extreme being thousands of 14C years between the insoluble bulk fraction and the organic fragments for the same sample. For all samples, radiocarbon analysis of the bulk fractions gave much younger ages than the hand-selected macro remains. Here, we discuss the age differences and possible sources of old and young carbon found in samples. The ages of the organic fragments showed the most consistency over the whole profile, and these fragments are least likely contaminated by younger material. Based on our results obtained on macro remains, this deposit is dated to MIS3 age. About 3 meters of fine-grained sediment were deposited here during ca. 8 ky. This could tell us more about the sediment budgets during some of the (Greenland) stadial-interstadial oscillations at the outlet of a major lake (e.g., Lake Maggiore) and the erosive power of glaciers during a phase preceding the global Last Glacial Maximum.
References
Braakhekke J, Ivy‐Ochs S, Monegato G, Gianotti F, Martin S, Casale S, and Christl M. 2020. Timing and flow pattern of the Orta glacier (European Alps) during the last glacial maximum. Boreas 49: 315-332.
Penck A, and Brückner E. 1909. "Die alpen im Eiszeitalter." Tauchnitz.
How to cite: Hajdas, I., Braakhekke, J., Monegato, G., Gianotti, F., Christl, M., and Ivy Ochs, S.: Different 14C ages for various fractions of peat, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12806, https://doi.org/10.5194/egusphere-egu25-12806, 2025.
Posters virtual: Fri, 2 May, 14:00–15:45 | vPoster spot 5
EGU25-19922 | Posters virtual | VPS7
The Lagoa Real Uranium Province: polycyclic evolution in the Brazilian geochronological recordFri, 02 May, 14:00–15:45 (CEST) | vP5.12
The Lagoa Real uranium province (LRUP) is the main Brazilian target for uranium. Their geochronological studies began in the 80s and provided controversial ages for mineralization. Since then, advances in geochronological methods, increased local petrological data, and knowledge of the uranium cycle have helped geosciences understand crust and mantle behavior over time. As a result, recent geochronological studies developed by CDTN researchers have now begun to reinterpret the evolution of the LRUP.
These studies dated metasomatic U-ore bodies providing ages between 545 Ma to 520 Ma (in situ U–Pb dating of andradite and titanite, Santos et al., 2023; Journal of South America Earth Science) coeval with the late Pan-African Cycle. Geochronological studies were also carried out on the host rocks (A-Type granites) of the mineralized bodies, providing ages between 1762 Ma to 1741 Ma (U–Pb dating of magmatic Zircon, Amorim et al., 2022; Journal of South America Earth Science), coeval to bimodal magmatism well documented in Brazil and Africa.
Although some of the data obtained suggest that granites might not be the source of uranium, their volcanic expression (metaryolites located to the NW of the LRUP) could be a good candidate. Thus, the uranium mobilization began before the metasomatism, through magmatic processes, coeval with the Post-Archean Uranium Recycling, a global event that incorporates U in the crust from the mantle. Furthermore, preliminary macroscopic and microscopic data from gneisses show evidence of partial melting related to regional metamorphism that may have occurred before metasomatism. This process generated Neoproterozoic uranium deposits in Namibia, at the Southern of the African counterpart of Brazil. Therefore, LRUP could result from overlapping processes in central Brazil accompanied by crustal differentiation episodes leading to a polycyclic evolution.
How to cite: Azevedo, R. A. and Rios, F. J.: The Lagoa Real Uranium Province: polycyclic evolution in the Brazilian geochronological record, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19922, https://doi.org/10.5194/egusphere-egu25-19922, 2025.
