The rapid increase in tree-ring radiocarbon concentration of 12‰ between 774–775 CE marked the first confirmed cosmic-origin event identified through annual tree-ring records. Subsequent studies have in-dependently verified this signal in dendrochronologically dated material from multiple regions, confirm-ing its global nature. Since then, several comparable events have been identified across different peri-ods. These radiocarbon spikes are of particular importance because they provide precise annual tie-points that can significantly improve chronological resolution in fields such as archaeology and geology. In this paper, we present a simple method for detecting such events in high-resolution radiocarbon da-tasets.

Optical Stimulated Luminescence (OSL) screening has emerged as a significant advancement in the field of luminescence dating applications. The employed portable luminescence readers offer practical and efficient tools for on-site measurements. In contrast to traditional luminescence dating in the laboratory, which often involves analyzing enriched quartz or feldspar mineral separates, portable OSL readers typically measure infrared (IR) or blue post-IR OSL signals from unprocessed bulk material. Here, we present a new device series that can be used as a portable OSL reader for dating purposes and luminescence screening: the OSL Helios reader. The reader has already been used in luminescence laboratories as a bench-top device for dosimetry research for almost twenty years. It recently received significant upgrades for better versatility. Our contribution demonstrates the application of the OSL Helios reader for luminescence screening on a loess profile, where luminescence signal intensities were assessed for specific sedimentological layers. The profile was measured using different versions of the OSL Helios reader, and the results were compared to those of the SUERC reader, which is commonly used as a portable reader in applications. Additionally, standard passive dosimeters (Al2O3:C and BeO), as well as detectors considered for emergency dosimetry (NaCl), were measured to determine the sensitivity of Helios devices. We conclude that the Helios reader performs similarly to the SUERC reader in most standard situations and can be considered an additional option for portable luminescence reader application.

This study addresses the challenge of signal crosstalk in luminescence measurements from single sand-sized mineral grains, utilising Electron-Multiplying Charge-Coupled Devices (EMCCD) for imaging. Crosstalk, or signal interference between adjacent grains, may significantly hamper the accuracy of luminescence analysis of signals emitted by single mineral grains. The research aims to minimise crosstalk, thereby enhancing the integrity of the luminescence data from each grain. The effects of altering the aperture size and the spacing between grains on the sample disc are investigated using the 110 °C thermoluminescence (TL) peak of quartz as an example. Specifically, the introduction of a newly designed sample disc with increased spacing between grain holes shows promising results in mitigating signal overlap, as evidenced by the experimental data. In particular, we demonstrate that the new design dramatically decreases signal crosstalk, enabling reliable automatic data analysis with minimal interference. The study offers practical solutions for enhancing the reliability of single-grain based luminescence chronologies and dosimetric assessments. By minimising signal crosstalk, more precise and reliable analyses of thermoluminescence and OSL signals can be obtained. To demonstrate the potential of the new design, for the first time, we show the estimation of trap parameters of the 110C peak in quartz at a single-grain level using an EMCCD camera, comparing it with the lifetime of the electrons in the 110C trap measured directly through storage experiments.

Late Quaternary landscape evolution in tropical environments, such as Indonesia, remains poorly constrained due to limited prior studies and mineral properties that are challenging for luminescence dating. In this study, single- and multi-grain luminescence measurements of quartz and K-feldspar were explored for fill terrace deposits at the Kampar Kanan River, Indonesia. Our objective is to develop a chrono-stratigraphic framework that allows the reconstruction of late Quaternary fluvial morpho-dynamics, including climatic change. Quartz measurements were made using blue and green stimulation and single-aliquot regenerative dose (SAR) and double SAR protocols. However, as none of the quartz signals were fast component-dominated, they were not used for dating. Infrared-stimulated luminescence of multiple grains of K-feldspar at 50 ºC (IR50) and post-infrared infrared-stimulated luminescence at 225 ºC (pIR50IRSL225) yielded sufficiently bright signal intensities for dating, and ages were calculated using either the average dose (ADM) or minimum age model (MAM). The luminescence chronology based on fading corrected pIR50IRSL225 data yields ages from Marine Isotope Stage (MIS) 6 or earlier to MIS 1. The chrono-stratigraphy indicates that the river was likely aggradational during climate transitions from wet to dry with the deposition of more gravelly material, and erosional during colder periods when overbank deposition of fines may have been coincident with increased vertical river erosion due to a stronger monsoon.

This study introduces a new method for measuring uranium, thorium decay chains, and K-40 in geological materials using NaI:Tl gamma spectrometry. The novel approach involves fitting data to model reference spectra via custom software, processing full mixed spectra to estimate pure component spectra quantifying radionuclides contents and evaluating their correlations. These correlations are crucial in calculating environmental dose rates for trapped charge dating. The methodology was validated using a Canberra InSpector 1000 spectrometer, with results cross-checked against high-resolution gamma spectrometry. With the use of the μRate web application, dose rates uncertainties were lowered by including correlated inputs, which results in improved precision in trapped charge dating.

The importance of the fast decaying signal of quartz for dating sediments is confirmed by years of research. In OSL dating, the single-aliquot regenerative-dose (SAR) protocol is applied to estimate age. The OSL signal measured in this protocol consists of components with different properties, particularly with different susceptibility to bleaching in sunlight. It is known how complicated it is to extract the fast decaying signal from other overlapping signals when blue light is used for stimulation. Decomposing OSL curves into components is unsuitable for dating purposes due to the challenges involved in handling many OSL curves for age estimation and obtaining consistent results across these curves. An OSL measurement method based on optical stimulation while the sample is heated, so-called thermally modulated OSL (TM-OSL), was recently implemented in the SAR protocol. Instead of the blue light (470 nm) in SAR (hereinafter referred to as SAR BLSL), red light (620 nm) is used for optical stimulation. In the protocol with TM-OSL measurement, the fast component is isolated and used for the OSL age determination. The advantage of this approach for a set of samples selected from various depositional environments is presented. The equivalent dose for the same samples was also determined using the SAR protocol that involved red light stimulation (620 nm, SAR RLSL) at an elevated temperature (230°C). The obtained results by the protocols using red light (SAR TM-OSL and SAR RLSL) are compared with the ones determined using the SAR BLSL protocol. Using TM-OSL in the SAR protocol leads to more precise dating results. The shape of the TM-OSL curve for the fast OSL component in quartz allows to identify in the TM-OSL a contribution from a signal of another origin. It prevents age underestimation by excluding from calculations the share of OSL components, which can be less stable.

In temperate regions trees typically exhibit growth sensitivity to climatic conditions during the growth season. Annual tree ring growth increments correlate with a variety of environmental factors. As an index of water use efficiency, δ13C is a preferred proxy to allow accurate interpretation of environmental factors critical for the tree growth, including changes in climate patterns, variation in the ambient temperature and precipitation. We assumed that isotopic differences within individual tree rings are likely to produce seasonal isotope fluctuations in the chronology that might be interpreted as response to environmental impacts. To verify the assumption, we measured δ13C in annual tree rings of Pinus Sylvestris L. split into 13 intra-annual segments each and checked δ13C correlations with temperature, precipitation, the number of sunshine hours and relative air humidity. For the investigation, we chose a site in north-eastern Lithuania, Zarasai, located in boreal latitude and remote from industrial pollution sources. The methodology of the research was based on high coherence of δ13C chronologies measured in the whole wood and α-cellulose extracted by means of two different methods. The experiment produced strong δ13C correlations with hydrometeorological parameters, especially in the earlywood formed in June

For modern fluvial systems, stage height, velocity, and cross-section help estimate a river’s discharge. However, understanding the amount and fluctuations of past discharges remains a challenge. The dimen-sions of the meander loops/oxbow lakes are directly proportional to the river’s discharge and the sedi-ment load type. Central West Bengal, India, has a complex network of numerous oxbow lakes as a rem-nant of the river Hooghly, a major distributary of the River Ganga. The present work revisits Schumm’s classic work to estimate river discharges from the meander loops and explores a potential proxy for es-timating past discharges. Thus, it is extended to reconstruct past climate using grain size data, facies analysis, and the dimension of the meander loops coupled with the luminescence chronology of oxbow lakes. The study reveals that the region received good rainfall during reported periods of intense mon-soon, and the increased discharge at different time intervals has given rise to numerous oxbow lakes. The discharge values have shown considerable fluctuations, rising to 15 to 20 times the current value and very few anomalously high, even up to 250 to 300 times, left unrecorded from other archives. The study shows the preservation of systematic growth of discharges and the meander loops with climate re-vealing events with anomalously high (and so highly disastrous) discharges at the scale of tens of thou-sands of years, usually missed from other archives. Results from Ichhamati and Hooghly River meander loops in West Bengal, India, indicate a manifold increase of discharges from the current during 1–1.5 ka (known as the Medieval Warm Period); around 2.2 ka and around 3.9 ka with low or gaps of enhanced monsoon, e.g., Little Ice Age and during 2.5–3.5 ka. This is an effort to show the potential of past mean-der loops to be explored well for comprehensive records.

The Daxing’anling Mountains are vulnerable to extreme weather and ecological degradation. Forests in this region have been substantially affected by extreme events; however, the pattern of future forest change remains uncertain. To determine the trends and reasons for extreme climate change, reanalysis data were used to assess the potential forest degradation resulting from future extreme climate events. Using tree-ring width chronologies of Pinus sylvestris var. mongolica (1952-2015) and Larix gmelinii (Rupr.) Kuzen (1962-2015), we performed a comparative analysis of the relationships between radial growth of these two tree species and extreme indices based on Pearson correlations. The functions between extreme climate and tree ring width were then used in the LASSO algorithm. Using the CMIP6 models under the intermediate emission scenario (SSP2-4.5), we projected the tree ring width of the two species from 2015 to 2100 using calibrated meteorological fields. The tree-ring chronologies of both species were correlated negatively with extreme warm temperature indices and positively with extreme precipitation indices. P. sylvestris responded more significantly to extremely high temperature indices and precipitation, with a certain lag effect. L. gmelinii responded significantly to extremely cold temperature indices. Tree species specificity may explain why the two species show different growth–climate relationships. The growth of P. sylvestris may decrease during extreme climate change conditions, whereas the effect on L. gmelinii future growth is not significant. The predicted growth series in the 2015–2100 period showed that three abnormally high values, six abnormally low values, and one extreme abnormally low value occurred in P. sylvestris, whereas there were two extreme abnormally low values, four abnormally low values, and four abnormally high values in L. gmelinii. Our findings can help predict the resilience and sustainability of forest ecosystems in the face of extreme climate change and contribute to forest management strategies.

The Żabinko exposure (western Poland) reveals the classic fluvio-aeolian succession known from studies in the European Sand Belt. Previous chronostratigraphic studies were mainly based on uncalibrated radiocarbon dates from organic sediments and thermoluminescence dating. The picture visible from these studies indicated a number of discrepancies between these methods. The new research in this exposure was based on optically stimulated luminescence (OSL) dating and calibrated radiocarbon dates. The results obtained indicate a general discrepancy between the results achieved by these two methods. While the radiocarbon dates provide some meaningful picture and allow correlation with previous studies, the results of OSL dating do not allow for a chronological model of sedimentary processes. The OSL dates show large inversions of the results and are clearly younger than the other dating results. Detailed analysis of OSL measurements shows radioactive disequilibrium and variability linked to differential stratification of sediments, significantly impacting the assessment of environmental dose rates. We believe that this atypical variability is presumably the result of postdepositional processes, such as changes in groundwater levels, chemical weathering and radionuclide migration.