Quaternary Geochronology最新文献

{"title":"Developing robust lake sediment chronologies using 210Pb, Pu and radiocarbon dating of pollen concentrates and macrofossil: A case study from Lake Surprise, Victoria, Australia","authors":"Asika Dharmarathna ,&nbsp;Haidee Cadd ,&nbsp;Cameron Barr ,&nbsp;Alexander Francke ,&nbsp;Quan Hua ,&nbsp;David Child ,&nbsp;Michael Hotchkis ,&nbsp;Atun Zawadzki ,&nbsp;Patricia Gadd ,&nbsp;Chris Turney ,&nbsp;Christopher E. Marjo ,&nbsp;John Tibby ,&nbsp;Jonathan J. Tyler","doi":"10.1016/j.quageo.2025.101686","DOIUrl":"10.1016/j.quageo.2025.101686","url":null,"abstract":"<div><div>The development of reliable sediment chronologies is crucial for accurate interpretations of decadal to century-scale palaeoenvironmental changes in the late Quaternary. Although radiocarbon dating of sedimentary sequences is commonly undertaken, not all the organic fractions are representative of atmospheric ¹⁴C levels, resulting in inaccurate age models. Whilst terrestrial plant macrofossils are widely considered ideal dating material – assuming they are contemporaneous with the horizons being dated – they are often sparse or absent. In this context, radiocarbon dating of pollen extracts is increasingly being used as alternative dating material. Here, we used pollen radiocarbon dating, alongside a suite of macrofossil and bulk sediment dates, to develop a chronology for the Holocene sediments of Lake Surprise, in Victoria, Australia. ²¹⁰Pb activity and Plutonium (Pu) concentrations and isotope ratios were also analysed to constrain the age of the uppermost sediments, augmented with recent historical markers, including the first arrival of <em>Pinus</em> pollen and the date of an earlier coring expedition at the site in 2004. With respect to the radiocarbon dates, we found an age offset between the plant macrofossils and bulk sediment dates of 260 ± 86 ¹⁴C years and an offset of ∼340 ¹⁴C years between plant macrofossil and pollen extracts. In both cases, macrofossil dates appeared to be “younger” than the bulk sediment and pollen dates. The offset between pollen and plant macrofossil dates was found to vary with sediment depth and generally correlate with carbonate concentration in the sediment. Using Fourier transform infrared spectroscopy (FTIR), we determined that the pollen extracts were not contaminated by either carbonate or charcoal. However, contamination by algal spores could not be ruled out, and we hypothesise that those algal spores may have assimilated aged dissolved inorganic carbon during periods of higher groundwater influx, thus altering the measured radiocarbon age of the pollen extract. Macrofossil and corrected pollen radiocarbon dates were incorporated in a Bayesian age-depth model which integrated ²¹⁰Pb activities and Pu data and bomb pulse C-14 dates validated using recent historical age markers. Our results suggest that it is possible to generate a robust geochronological framework for Lake Surprise using radiocarbon dating back to at least ∼10,846 cal yr BP.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"89 ","pages":"Article 101686"},"PeriodicalIF":1.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pysochron: A Python-based solution for calculating cosmogenic 26Al/10Be isochron burial ages","authors":"William E. Odom","doi":"10.1016/j.quageo.2025.101675","DOIUrl":"10.1016/j.quageo.2025.101675","url":null,"abstract":"<div><div>Cosmogenic ²⁶Al/¹⁰Be isochron burial dating is a powerful tool for dating sediment burial over the past several million years. By measuring in-situ ²⁶Al and ¹⁰Be in a suite of samples from the same depth in a buried deposit, it is possible to quantify the inventory of cosmogenic nuclides produced after burial, date the burial of shallow sediments, identify sediment reworking, and calculate paleo-erosion rates. While this approach has been used to date materials around the world for over a decade, few published codes exist for performing ²⁶Al/¹⁰Be isochron calculations. The isochron calculation options that are available typically rely on numerous files and libraries, rendering modification and troubleshooting difficult. Moreover, the widespread use of proprietary programming languages – and their associated addon packages – can place an additional financial burden on an already costly endeavor.</div><div>Pysochron (<span><span>https://code.usgs.gov/recon/pysochron</span><svg><path></path></svg></span>) provides a solution to these issues. In its base form, it exists as a single script that can be easily modified, upgraded, and shared. Because it was developed in an open-source environment, all required computational packages are available free of charge. A user-friendly interface allows rapid modification of calculation parameters, and an automated commentary on isochron results provides insights and recommendations. Pysochron has been validated with 40 published cosmogenic ²⁶Al/¹⁰Be burial isochrons around the world, with burial ages ranging from ∼5 Ma to ∼180 ka. As such, it is a promising option for members of the cosmogenic nuclide community seeking a straightforward, cost-effective, and flexible solution to isochron burial dating challenges.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"89 ","pages":"Article 101675"},"PeriodicalIF":1.7,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144196340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiocarbon and luminescence age estimate database for the Willandra Lakes Region World Heritage Area: a reliability-assurance assessment","authors":"Nathan R. Jankowski ,&nbsp;Nicola Stern ,&nbsp;Elizabeth Foley ,&nbsp;Geraldine Jacobsen ,&nbsp;Haidee Cadd ,&nbsp;Tegan Smith ,&nbsp;Willandra Lakes Region Aboriginal Advisory Group","doi":"10.1016/j.quageo.2025.101678","DOIUrl":"10.1016/j.quageo.2025.101678","url":null,"abstract":"<div><div>The legacy of geochronological data gathered within the Willandra Lakes Region World Heritage Area over more than 60 years has produced a corpus of age estimates that are now of varying reliability as a result of improvements in laboratory, measurement, analytical, and reporting procedures. A database of all known radiocarbon and luminescence age estimates was compiled and the reliability of each age estimate was ranked from A (most reliable) to C (least reliable). A total of 128 of 269 radiocarbon, 138 of 339 optically stimulated luminescence (OSL), and 0 of 53 thermoluminescence ages were given a Rank A score. Using only Rank A OSL age estimates, a Bayesian modelled chronostratigraphic framework for the Lake Mungo lunette was developed for the Lower Mungo (56.2 ± 3.0 to 37.7 ± 1.0 ka), Upper Mungo (36.4 ± 1.1 to 34.1 ± 1.7 ka), Arumpo (25.1 ± 0.6 to 18.2 ± 0.5 ka), and Zanci (18.2 ± 0.5 to 17.2 ± 0.7 ka) Units. Three lacustrine phases were identified using Rank A radiocarbon ages on otoliths and mussel shell: system-wide high water ∼55–35 ka cal BP (continuing in the north until ∼30 ka cal BP); a short pulse reaching to Lake Outer Arumpo ∼29–24 ka cal BP; and a final saline phase at Lake Mungo ∼21–17 ka cal BP, whilst freshwater conditions were maintained throughout this period at Lake Mulurulu. Only 62 of 143 radiocarbon ages associated directly with archaeological features were given a Rank A score and because they are derived from a restricted range of site types, some with restricted temporal distributions, they are not a reliable basis for documenting the history of land use and occupancy. Continued research is needed to increase the number of reliable age estimates from depositional, palaeohydrological, and archaeological contexts in different landforms to produce a clearer understanding of both palaeoenvironmental change, and the history of land use and occupancy of this enduring cultural landscape.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"89 ","pages":"Article 101678"},"PeriodicalIF":1.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144105129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing and dating authigenic phosphates from the sedimentary infill of Atapuerca archaeo-paleoanthropological cave sites (Spain)","authors":"I. Campaña ,&nbsp;M. Duval ,&nbsp;A. Álvaro-Gallo ,&nbsp;V. Guilarte ,&nbsp;Q. Shao ,&nbsp;A.I. Ortega ,&nbsp;L.J. Arnold ,&nbsp;M. Demuro ,&nbsp;J.M. Bermúdez de Castro ,&nbsp;E. Carbonell","doi":"10.1016/j.quageo.2025.101674","DOIUrl":"10.1016/j.quageo.2025.101674","url":null,"abstract":"<div><div>We present the results of a characterization and dating study of eight authigenic apatite samples collected from various stratigraphic units of three cave sites across the Atapuerca complex, namely Gran Dolina, Galería Complex and Sima del Elefante. Characterization analyses using X-ray diffraction, X-ray fluorescence and Electron Spin Resonance (ESR) spectroscopy have been used to determine the nature and composition of the samples: seven of them are mostly made of hydroxyapatite, while one is composed of crandallite, and all show variable amounts of contamination by calcite and/or sediment. The timing of authigenic apatite formation, which results from the weathering of the limestone in a karstic environment, has been tentatively constrained through a combination of bulk and spatially resolved analyses using ESR and U-series methods. The dating results obtained enable the identification of various formation events during the Middle and Late Pleistocene at each site, around 170–180 ka and 110–120 ka in Gran Dolina, ∼250 ka and ∼40 ka in Galería Complex, and, possibly, ∼360 ka in Sima del Elefante. Importantly, all these ages are significantly younger than the depositional age of the host sediment, thus confirming the post-depositional nature of authigenic apatite. Additionally, the absence of age consistency across sites suggests that they have all experienced independent diagenetic events, which cannot be attributed to the overall karst dynamics of the Sierra de Atapuerca, but should rather be regarded as local processes.</div><div>Beyond the dating results, this study provides an overview of the potential and current limitations of ESR and U-series methods applied to Quaternary authigenic apatite. The main complication regarding the ESR method lies in the evaluation of the internal dose rate given the high uranium concentrations measured in the samples, and the absence of a directly related alpha efficiency value for this type of material. Laser ablation U-series analyses also highlight the methodological challenges caused by significant spatial heterogeneity of the U-series data across the apatite samples, which reflects the complexity, non-uniformity and long duration of apatite formation processes around the limestone blocks.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"89 ","pages":"Article 101674"},"PeriodicalIF":1.7,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144241540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New chronological constraints on the history of the Kalahari Group from the Upper Ugab Valley, Namibia","authors":"A. Kuzmenko ,&nbsp;A. Torfstein ,&nbsp;A. Hidy ,&nbsp;Y. Geller ,&nbsp;S. Vainer ,&nbsp;A. Matmon","doi":"10.1016/j.quageo.2025.101677","DOIUrl":"10.1016/j.quageo.2025.101677","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The sedimentary fill of the Kalahari Basin, which extends across several countries in southern and central Africa, records landscape evolution processes and holds archeological evidence of early hominid occupation. Recent studies have demonstrated that the majority of the Kalahari Group sediments were deposited between the Pliocene and the recent present. However, due to limited access to natural outcrops in the flat Kalahari topography, the chronology of the sequence, mostly its earlier part, is not well constrained.&lt;/div&gt;&lt;div&gt;Here, we set out to study the geologic history of the Ugab drainage system, located in northern Namibia adjacent to the western margin of the Kalahari Basin. The evolution of the upper Ugab drainage system and the adjacent region of the Kalahari Basin were modulated by similar climatic and geologic conditions and processes. Furthermore, the continental water divide at the Ugab catchment headwaters is pushed eastward, further than any ephemeral river draining to the Atlantic Ocean. This geometry raises the possibility of a local drainage divide migration and implies that the upper part of the Ugab drainage system was part of the Kalahari Basin until captured westward to the Atlantic Ocean. Thus, the lower part of the sedimentary section exposed in the upper Ugab Valley may be a remnant of the eroded Kalahari Group. We report new chronological constraints on Kalahari Group units from the “Base Camp” outcrop in the upper Ugab Valley, using cosmogenic &lt;sup&gt;26&lt;/sup&gt;Al and &lt;sup&gt;10&lt;/sup&gt;Be dating in quartz and U-Th dating of carbonate cements and tufa. The study site is comprised of a ∼20 m thick cemented conglomerate sequence overlain by 20–25 m of carbonate and siliceous duricrusts. We developed a novel multi-stage numerical model for interpreting cosmogenic &lt;sup&gt;26&lt;/sup&gt;Al and &lt;sup&gt;10&lt;/sup&gt;Be data, following key stages of landscape evolution through a Monte Carlo simulation. This model reconstruction indicates that fluvial deposition of at least 70–100 m of sediments in the upper Ugab Valley had commenced most likely during the Miocene. Following sediment accumulation, surface stability was maintained for a mean most probable duration of 8.86 &lt;sup&gt;+6.82&lt;/sup&gt;/&lt;sub&gt;-1.51&lt;/sub&gt; Myr, and then followed by a short (&lt;∼300 ka) erosional phase that removed a minimum of 32–53 m of the valley fill. Fine-grained sediments were then deposited during the Middle Pleistocene on top of the erosional surface and cemented by calcite and dolomite at a low gradient valley floor. The beginning of the final incision through the duricrust layer and the subsequent emergence of ground water springs are indicated by tufa deposits dated to 58.3 &lt;sup&gt;+22.2&lt;/sup&gt;/&lt;sub&gt;-17.5&lt;/sub&gt; ka. Quartzite samples from the re-exposed top of the conglomerate show simple cosmogenic exposure ages that range between 15.8 and 39.4 ka. Though the model suggests a gradual exposure, with at least two different incision rates over time, the overall exposure time i","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"89 ","pages":"Article 101677"},"PeriodicalIF":1.7,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143936184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the potential of a modified post-isothermal IRSL (pIt-IR) protocol to circumvent the problems posed by anomalous fading in polymineral fine grains","authors":"Nina Ataee,&nbsp;Helen M. Roberts,&nbsp;Geoff A.T. Duller","doi":"10.1016/j.quageo.2025.101676","DOIUrl":"10.1016/j.quageo.2025.101676","url":null,"abstract":"<div><div>Attempts to find a ‘non-fading’ infrared stimulated luminescence (IRSL) signal have been ongoing in the past two decades, due to complications regarding measurement and application of anomalous fading as well as higher age uncertainty introduced by fading correction. In this research, the potential of the post-isothermal IRSL (pIt-IR) protocol to generate ages without the need for fading correction is investigated. Polymineral fine grain samples were collected from a sediment core from Lake Chew Bahir in Ethiopia which is supported by independent age control. The equivalent dose (D_e) values determined using the pIR₅₀IR₂₂₅ pIt-IR protocol are in agreement with the fading corrected pIRIR₂₂₅ D_e values for the upper ∼40 mcd of the core (∼200 Gy), below which the pIR₅₀IR₂₂₅ pIt-IR D_e values underestimate the fading corrected pIRIR₂₂₅ D_e values. This underestimation appears to be a consequence of the IR₅₀ signal approaching field saturation since pIt-IR D_e determination depends on both IR₅₀ and pIRIR₂₂₅ signals. Increasing the measurement temperature of the first IR signal in the pIRIR₂₂₅ pIt-IR protocol (from 50 to 150 °C, i.e. pIR₁₅₀IR₂₂₅ pIt-IR) appears to extend the upper limit of the pIt-IR protocol by producing D_e values that are consistent both with the fading corrected pIRIR₂₂₅ D_e values (within 1σ uncertainties), and also in agreement with the ages of two known-age tephra (within 2σ uncertainties) down to ∼90 mcd of the core (∼450 Gy, ∼180 ka). This demonstrates that the pIt-IR protocol is capable of producing D_e values and ages that do not require fading correction as long as the first IRSL signal in the pIRIR₂₂₅ pIt-IR protocol is not in field saturation. However, verification of the accuracy of the D_e values and ages generated using the pIt-IR protocol is provided by comparison of the fading corrected IR₅₀ and corrected pIRIR₂₂₅ D_e values/ages, which could otherwise be collected directly through more conventional pIRIR protocols that are shorter in duration than pIt-IR measurement sequences. This raises questions regarding the benefit of using a pIt-IR protocol rather than a pIRIR protocol for dating, the primary advantage of which remains circumvention of the problems posed by anomalous fading for sediments that are younger than the field saturation values of the first IR signal measured in a pIt-IR protocol.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"88 ","pages":"Article 101676"},"PeriodicalIF":1.7,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143921853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining equivalent dose for optically stimulated luminescence (OSL) dating with physically meaningful dose response curves","authors":"George Kitis ,&nbsp;Georgios S. Polymeris ,&nbsp;Jun Peng","doi":"10.1016/j.quageo.2025.101671","DOIUrl":"10.1016/j.quageo.2025.101671","url":null,"abstract":"<div><div>Non-linear dose–response curves are common in many thermoluminescence (TL) and optically stimulated luminescence (OSL) dosimetric applications, especially in TL and OSL dating. In most cases, these calibration curves are characterized by saturating exponential expressions; consequently, the accuracy of equivalent dose <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> is highly dependent on the specific position along the saturating exponential curve. In the present work, accuracy is estimated through numerical simulations using novel analytical dose–response expressions based on the Lambert <span><math><mi>W</mi></math></span> function. These simulations are subsequently extrapolated to experimental OSL dose–response curves obtained from dating experiments. The <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> was estimated by solving the new dose–response expressions and the error <span><math><msub><mrow><mi>σ</mi></mrow><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></msub></math></span>, arising from the uncertainty of the natural signal, was evaluated through analytical expressions derived using error propagation theory. Finally, an analytical expression was derived for the derivative of the dose–response function, and the accuracy of <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> correlated with the derivative at the point corresponding to the unknown dose. The newly derived analytical expressions, based on physical models, enable the determination of <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> in both linear and non-linear regions of the dose response curves (DRC). This model offers a significant advantage over other existing empirical expressions, whose results lack theoretical justification. The present study offers a general and objective method to identify samples potentially affected by <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> saturation, through direct evaluation of the derivative of the DRC.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"88 ","pages":"Article 101671"},"PeriodicalIF":1.7,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Testing micro-aliquot SGC and LnTn methods for age determination up to 780 ka using coarse K-feldspar grains from Nihewan Basin, northern China","authors":"Shengxia Xu ,&nbsp;Xue Rui ,&nbsp;Yujie Guo ,&nbsp;Bo Li","doi":"10.1016/j.quageo.2025.101673","DOIUrl":"10.1016/j.quageo.2025.101673","url":null,"abstract":"<div><div>The Nihewan Basin in northern China is a key region for the study of Paleolithic archaeology of East Asia, due to the discovery of Paleolithic sites with ages spanning the entire Pleistocene. However, many Paleolithic sites assigned to the Middle to Late Pleistocene are still not dated or poorly dated, which affects our understanding the stone tool technology evolution in the Nihewan Basin. The post-infrared infrared stimulated luminescence (pIRIR) signal from potassium-rich feldspar grains can be applied to date Middle to Late Pleistocene sediments, as this signal has significantly lower fading rate. In this study, to establish a robust chronological framework of the Nihewan Paleolithic sites more effectively, a micro-aliquot (MA) standardised growth curve (SGC) was constructed for pIRIR dating. The established MA SGC was tested for sediments up to 780 ka, and the obtained MA SGC D_e results were compared with those from single-aliquot (SA) measurement. Results from a number of tests suggest that the disagreement between MA and SA results is due to a small amount of anomalous fading in dimmer grains, which can be corrected by T_n threshold. By projecting the weighted mean L_n/T_n ratios (after T_n threshold correction) onto the MA SGC, the obtained pIRIR ages increase from top to bottom, and the sample from just above the B/M boundary (∼780 ka) yielded an age of <span><math><mrow><msubsup><mn>725</mn><mrow><mo>−</mo><mn>117</mn></mrow><mrow><mo>+</mo><mn>179</mn></mrow></msubsup></mrow></math></span> ka, which is consistent with the expected age. Our result suggested that the MA SGC method can reduce instrument time and has the potential to provide reliable age up to ∼700–800 ka in this region.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"88 ","pages":"Article 101673"},"PeriodicalIF":1.7,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143928946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study the effect of irradiation, optical bleaching and heating on the thermal stability of OSL signals of quartz from dune sands in northern China","authors":"Zhijun Gong ,&nbsp;Hong Yan ,&nbsp;Ming Luo","doi":"10.1016/j.quageo.2025.101672","DOIUrl":"10.1016/j.quageo.2025.101672","url":null,"abstract":"<div><div>Variability in the thermal stability of quartz OSL signals has been observed for Late Quaternary sediments in different geographic setting in China. In this study, quartz grains were extracted from the Taklimakan Desert and the Hunshandake sandy land and the thermal stability of their quartz OSL signals were further investigated. Firstly, quartz aliquots of Taklimakan Desert were measured by using pulse annealing tests. It was found that the quartz from the Taklimakan Desert exhibited highly variable pulse annealing curves, showing the significant differences in the thermal stability of quartz OSL signals. Secondly, laboratory irradiation, optical bleaching and heating experiments were designed to test their effects on the thermal stability of quartz OSL signals. To compare the thermal stability among different quartz aliquots more efficiently, the thermal remnant ratio (TRR) was used as the proxy for the thermal stability, which was measured by using the ratios of the remnant OSL signals measured after cut-heat to 280 °C to those measured after cut-heat to 240 °C in the simplified pulse annealing tests. For the quartz samples from the Taklimakan Desert, it was found that the operated cycles of dosing and bleaching have relatively insignificant effects on the TRR values of quartz OSL. For the effect of heating on TRR value, it is dependent on samples. When the initial TRR value of quartz OSL is significantly less than 0.9, heating to high temperatures (e.g. ≥400 °C) has significant effect on the TRR value of quartz OSL. When the initial TRR value of quartz OSL is equal to or larger than 0.9, the effect of heating on the TRR value is not obvious. Such results suggest that different heating history of quartz plays an important role in the thermal stability of the quartz OSL signal. Thirdly, the TRR values of quartz OSL of Taklimakan Desert were compared with those of Hunshandake sandy land. For the Taklimakan Desert, it was found that only a part of the quartz grains exhibit TRR values equal to or larger than 0.9. In comparison, the TRR values for the majority of quartz grains from the Hunshandake sandy land are equal to or larger than 0.9. Such results demonstrate the different heating histories of quartz grains between the Taklimakan Desert and the Hunshandake sandy land, i.e. only a part of quartz grains from the Taklimakan Desert suffered from high temperature heating, while the majority of quartz grains from the Hunshandake sandy land suffered from high temperature heating during geological past. The different heating histories of quartz grains between the Taklimakan Desert and the Hunshandake sandy land are consistent with the different geological settings of the two regions. Our studies suggest that the proxy (i.e. TRR) of the thermal stability of quartz OSL has advantages over luminescence sensitivity for distinguishing the provenance of sediments with different heating histories.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"88 ","pages":"Article 101672"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An evaluation of two cryptotephra quantification methods applied on lacustrine sediments with distant Laacher See tephra fallout","authors":"V. Meier ,&nbsp;T. Hrstka ,&nbsp;J. Ohser ,&nbsp;J. Siquans ,&nbsp;B. Brandstätter ,&nbsp;G. Kletetschka ,&nbsp;D. Vondrák","doi":"10.1016/j.quageo.2025.101670","DOIUrl":"10.1016/j.quageo.2025.101670","url":null,"abstract":"<div><div>Detailed quantification of volcanic glass is crucial for improving the resolution of paleoenvironmental reconstructions and facilitating more accurate comparisons between distant sedimentary cryptotephra records. Here we present and evaluate two methods for the quantification of cryptotephra, shown on lake sediments from a site with distant Laacher See tephra fallout. Our methods initiate with delineating the extent and distribution of the cryptotephra layer within the sediments, accomplished through the integration of X-ray fluorescence (XRF) and computed tomography (medical- and μ-CT). The first quantification method involves the well-established process of shard extraction through stepwise density separation, followed by improved and statistically evaluated quantification introducing a new standardized marker. While the method itself is used widely for many years among cryptotephra researchers, we demonstrate how the new marker improves its precision for cryptotephra quantification, providing a robust, straightforward laboratory-based technique. Additionally, we introduce an innovative, software-based method that combines an SEM-based automated mineralogy analysis on thin sections with customized image analysis, which allows to study the area fraction of the glass phase, its depth-dependent variation, particle concentration with a focus on clustering behavior, depth-dependent particle count, total particle count, and particle size distribution within the glass phase. The significance of both methods lies in the efficiency and precision of cryptotephra quantification, enabling a deeper understanding of shard concentration and distribution. This study emphasizes the methodological innovations, offering improved tools for cryptotephra quantification, without focusing on detailed application-based analyses.</div></div>","PeriodicalId":54516,"journal":{"name":"Quaternary Geochronology","volume":"88 ","pages":"Article 101670"},"PeriodicalIF":1.7,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}