Volume 48 (2021): Edizione 1 (January 2021)

The Gliwice Luminescence Laboratory (GLL) is a part of the Institute of Physics – Centre for Science and Education at the Silesian University of Technology, which has gradually evolved since the 1980s. To date, nearly 3500 samples have been dated using luminescence from materials such as ceramics, bricks, and sediments from archaeological and geological sites. Currently, the laboratory is equipped with four luminescence readers and three gamma spectrometers, allowing luminescence dating of approximately 300 samples annually for the needs of research projects. This article focuses on the laboratory procedures used in GLL to obtain luminescence ages. Recent improvements of the GLL's facilities and new equipment, as well as the performance spanning the Laboratory's 30 years of activity, are discussed in terms of obtained results and the involvement in national and international projects.

The prehistoric settlement of the west coast of the Senegalese-Mauritanian basin is established from archaeological remains and coal samples collected, sometimes in a stratigraphic context. However, the chronology issued, in the Before Present (BP) age, does not take into account the taphonomic context of the sites and the local reservoir age. Therefore, this article revisits the chronologies obtained based on the ¹⁴C literature and dating(s) acquired. Changes in time and duration of human occupancy of the area are shorter or longer depending on adequate yields of local reservoir age (Ndeye, 2008), which is a relevant element for marine samples. Thus, the archaeological implications observed with the reservoir effect are the rejuvenation or ageing of the dates, the age of the sites, the duration of occupation prehistoric or historical sites studied. Using the calibration programmes, it is noted that for the site of Senegal (Khant), without taking into account the reservoir effect, the human occupation is a priori, from the fifth millennium (Ancient Neolithic) to the third millennium BC (Middle Neolithic). However, if this marine reservoir effect is applied, the chronological periodisation goes from the fourth millennium to the first millennium. For the Mauritanian sites, the reservoir age correction is necessary for the Chami site while for the Tintan site is not required. Therefore, the calibrated archaeological chronologies obtained after the application of the marine reservoir effect are more relevant.

Establishing a chronology of events is a critical step in reconstructing the palaeoclimate and it is important for all types of environmental records, including speleothems. Here, we analysed a unique series of flowstones deposited between 3.2 Ma (marine isotope stage (MIS) Km³) and 0.08 Ma (MIS 5). The studied flowstones are located in a classic karstic environment, the Račiška Pečina Cave in south-western Slovenia. Further, a detailed chronology of events was constructed based on oxygen isotope stratigraphy (OIS), combined with magnetostratigraphy and U-series dating. Two curves were selected as reference records where the LR04 record was used as the global curve and a Mediterranean record was used as the regional curve. The Račiška Pečina profile was divided into two segments separated by a principal disconformity. The lower segment correlated better with the regional Mediterranean curve, while the upper segment was with the global LR04 curve. These findings suggest that the main factors controlling environmental conditions in the cave area changed between 3.2 and 0.8 million years ago.

The applicability of the single-aliquot regenerative-dose (SAR) protocol, by using the optically stimulated luminescence (OSL) signal of quartz as well as the post-infrared–infrared (pIRIR) signals of polymineral fine grains, namely pIRIR₂₂₅ and pIRIR₂₉₀, was assessed for dating loess in New Zealand South Island. OSL signals of quartz grains displayed low sensitivity. However, the application of repeated irradiation/bleaching cycles did not result in an increase in sensitivity; annealing in the 300–500°C temperature range generated the sensitisation of both the 110°C thermoluminescence (TL) peak as well as the OSL signal, likely by activation of yet unidentified luminescence centres. After heating, the quartz signal is comparable to that of ideal samples, but the annealing is precluding successful dating. On the other hand, feldspar infrared-stimulated signals displayed satisfactory properties, allowing estimation of ages ranging from 14 ± 1–29 ± 3 ka for the investigated deposit. It was shown that pIRIR₂₂₅ and pIRIR₂₉₀ methods have potential for dating loess in the South Island of New Zealand, based on the following observations: (i) Dose recovery tests were successful with recovered-to-given dose ratios with a <10% deviation from unity, (ii) constant residual values of about 4 Gy and about 10 Gy were obtained after exposures for 48 h in the case of pIRIR₂₂₅ signals and 96 h in the case of pIRIR₂₉₀ signals, respectively, (iii) while a slight dose-dependence of the residual was reported, and for a dose as large as 1600 Gy the residual values are ≅9 Gy and ≅19 Gy for pIRIR₂₂₅ and pIRIR₂₉₀ signals, respectively.

A set of brick samples from 26 historical buildings in SE Poland was taken for archeomagnetic study. As a result of this study, the secular variations of inclination of the geomagnetic field from 1200 to 1800 AD were defined for SE Poland. The course of them is approximately the same as obtained in other parts of Europe. The only remarkable difference is a more rapid and deeper drop of inclination noted in SE Poland at the end of the 18^th century. The regional curve of secular variations of inclination for SE Poland differs substantially from the coeval curve defined earlier for N Poland (Gdańsk) in their segments dated at the first half of the 18^th century, where a deep minimum of inclination was disclosed in the bricks from N Poland only. The reuse of medieval bricks for the construction of objects giving this minimum or later secondary heating of original bricks can be a reason for the difference observed. Further archeomagnetic studies of the bricks of the last millennium are necessary in SE Poland to eliminate the gaps and uncertainties in the regional curve of secular variations of inclination.

Infrared Radiofluorescence (IR-RF) is a relatively new method for dosimetric dating of the depositional timing of sediments. This contribution presents an interlaboratory comparison of IR-RF measurements of sedimentary feldspar from eight laboratories. A comparison of the variability of instrumental background, bleaching, saturation, and initial rise behaviour of the IR-RF signal was carried out. Two endmember samples, a naturally bleached modern dune sand sample with a zero dose and a naturally saturated sample from a Triassic sandstone (~250 Ma), were used for this interlaboratory comparison. The major findings of this study are that (1) the observed IR-RF signal keeps decreasing beyond 4000 Gy, (2) the saturated sample gives an apparent palaeodose of 1265 ± 329 Gy and (3) in most cases, the natural IR-RF signal of the modern analogue sample (resulting from natural bleaching) is higher than the signal from laboratory-induced bleaching of 6 h, using a solar simulator (SLS). In other words, the laboratory sample bleaching was unable to achieve the level of natural bleaching. The results of the investigations are discussed in detail, along with possible explanations.

Trapped charge dating method using electron spin resonance (ESR) of quartz is progressively used for sediment dating. ESR signals can be used for accurate age estimation only when these signals are zeroed by sunlight exposure before the layer creation or when one knows their ESR residual level (the part of the signal that is not bleached). It is well known that the ESR signal related to the Al-hole centres in quartz used for sediment dating has a significant residual signal. From the point of view of luminescence models, as a hole trap, the Al-hole centre is considered as a recombination centre in quartz. Recently, it was demonstrated experimentally that the ESR signal of the Al-hole centre is dependent on the total dose absorbed by the quartz sample in the past. The same effect was confirmed by simulations of the charge transport processes for a model including two recombination centres. Here, the dependence of residual hole concentration (RHC) in the recombination centres on the total dose absorbed by a sample in the past is studied in detail by computer simulations for a wide range of model parameters. The impact that the various relations of centre parameters have on the dependence of the residual as a function of dose is investigated and the implications for the dating practice are discussed.

In terms of fine-grain luminescence dating applications, the efficiency of α-radiation in producing luminescence is an important issue when determining environmental dose rates. Efficiency is usually assessed by measuring the ratio of luminescence intensities induced by known α and β laboratory doses. Consequently, most thermoluminescence (TL)/optically stimulated luminescence (OSL) readers besides the standard ⁹⁰Sr/⁹⁰Y β-source can also be equipped with a ²⁴¹Am α-source. A crucial point is, however, the calibration of these sources. The calibration of β-sources is routinely performed using standard quartz samples previously irradiated by a known γ-dose, though, in the case of α-sources, the procedure is less standardised, partly because there are no calibration materials with a known α-efficiency value.

In this study, we aimed to cross-calibrate the built-in α-source of a RISØ TL/OSL DA-20 luminescence reader by testing and comparing five procedures, applying different samples (quartz and polymineral), different protocols multiple aliquot regeneration (MAR) and single aliquot regeneration (SAR) and different calibration sources. Throughout the tests, the performance of the fine-grain RISØ calibration quartz was also assessed.

Regardless of the applied procedure, the calculated α-dose rates with one exception gave similar results. On the one hand, the applied polymineral sample due to potential fading, fairly high residuals after bleaching and relatively low infrared stimulated luminescence (IRSL) sensitivity proved to be the least optimal choice for cross-calibration. On the other hand, the tested natural fine grain quartz gave almost identical results when using different types of bleaching and different calibration α-sources. The mean dose rate determined for the source was 0.080 ± 0.004 Gy/s.

The cross-calibration by using the RISØ fine grain quartz yielded somewhat higher but at the apparent uncertainty of luminescence dating still not significantly different dose rate for the source under calibration. Tests showed that the calibration quartz saturates at a relatively low α-dose, and the shape of α- and β-dose-response curves also depart from each other quite early, suggesting that cross-calibration with this material seems to be reliable only at low doses. For the first time, the a-value of the fine-grain calibration quartz was also determined using the freshly calibrated α-source, and the measurement yielded a 0.054 ± 0.003 value. We propose that after further validation of this result, the RISØ calibration quartz can ease the dose rate assessment of uncalibrated α-sources in the future.

Olivine has so far attracted limited attention as a potential luminescence dosimeter. In particular, there is a dearth of information concerning the luminescence properties of geochemically characterised, pure olivine samples. Six well-characterised olivine samples from four intraplate settings are investigated in this study, including emission wavelengths and intensities, growth of signal with absorbed dose, signal stability and recovery of a given dose with a single aliquot regeneration (SAR) protocol. All tested olivines share a low-temperature (90–100°C) UV/blue thermoluminescence (TL) peak, and five of six samples also produce a low-temperature red/yellow emission. Higher temperature TL peaks, which would be thermally stable over geological timescales and could be used for dating, are rarely observed at low doses (c. 46 Gy), but detectable though dim at significantly higher doses (c. 460 Gy). Photostimulated luminescence (PSL) emissions are very dim, but reliably detected emissions are stimulated by blue, yellow and infrared (IR) light. PSL yielded generally successful dose recovery results; however, all tested signals are prone to significant anomalous fading and complex thermal transfer between unbleachable and bleachable traps. These characteristics must be addressed if olivine is to be used as a natural dosimeter for luminescence dating. Given the variety of luminescence responses, it appears that olivine samples in future dating work may need to be individually characterised prior to measurement.

Violet stimulation is a new development in optical dating which has been suggested to extend the upper age limit of optically simulated luminescence (OSL) dating of quartz. Despite the reported advantage, few validation tests and applications have been published so far. The present study investigated the violet stimulated luminescence (VSL) using a single aliquot regenerative dose (SAR) protocol and a multiple aliquot additive dose (MAAD) protocol. Sedimentary quartz samples from four archaeological sites in Europe with independent age controls spanning 40–900 ka were used, including Grotte Mandrin (France), Brooksby Quarry (UK), Cueva Negra del Estrecho del Río Quípar (Spain) and Sima de las Palomas del Cabezo Gordo (Spain). The equivalent dose of a relatively young sample (∼40 ka) was successfully determined. However, significant underestimations were observed for older samples with higher doses. These findings indicate the need for further development of the measurement protocol to date high-dose natural samples.

Five dating protocols with post-infrared infrared (IR) stimulated luminescence signals (i.e. pIRIR) were performed on the K-feldspar of loess samples. Two of them were the single-aliquot regenerative-dose protocol (SAR) with two-step pIRIR stimulation, with the first IR stimulation at 50°C or 200°C and the second at 290°C (pIR₅₀IR₂₉₀, pIR₂₀₀IR₂₉₀). Two of them were the SAR protocols with five-step or six-step IR stimulation at multiple elevated temperatures to 250°C or 300°C (MET-pIRIR₂₅₀, MET-pIRIR₃₀₀). The final one was the multiple-aliquot regenerative-dose (MAR) protocol with the MET-pIRIR₃₀₀ signal, together with a 500°C heat treatment administered before the test dose (‘MAR with heat’). The results show that when the equivalent dose (D_e) of the sample was less than 500 Gy, all of the protocols gave consistent results; however, when D_e exceeded 750 Gy, all of the SAR protocols underestimated D_e. The pIR₅₀IR₂₉₀ signal had the highest degree of underestimation, while the pIR₂₀₀IR₂₉₀, MET-pIRIR₂₅₀ and MET-pIRIR₃₀₀ signals had similar D_e values and similar degrees of underestimation. Possible reasons for the SAR D_e underestimation are discussed. We suggest that only the ‘MAR with heat’ protocol is suitable for samples with D_e exceeding 750 Gy.

The post-infrared (post-IR) pulsed blue light stimulated luminescence (PBLSL) signal has been employed to determine the equivalent dose (D_e) of feldspar contaminated quartz grains, but it sometimes suffers from the interference of feldspars. Since the green light stimulated luminescence (GLSL) signal of feldspars might be more reduced by a prior IR stimulation, we compared the characteristics of post-IR PBLSL and post-IR pulsed GLSL (post-IR PGLSL) signals of quartz and feldspars in this study to evaluate the feasibility of employing the green light for pulsed stimulation. We investigated the effect of the signal integration period, pulsed stimulation temperature, and prior IR stimulation temperature on the intensities of post-IR PBLSL and post-IR PGLSL of quartz and feldspars, and evaluated the potential feldspar interference on these two signals for the hypothetical and artificial quartz-feldspar mixture. The results demonstrate a lower feldspars contribution for the post-IR PGLSL signal. The feldspar interference only slightly increases with the increase of integration period for the post-IR PGLSL signal measured at low stimulation temperature, which permits a long integration period to be employed to enhance the signal to noise ratio. This study shows that the green light is a promising alternative for pulsed stimulation to suppress the feldspar contribution.

In optically stimulated luminescence (OSL) dating, statistical age models for equivalent dose (D_e) distributions are routinely estimated using the maximum likelihood estimation (MLE) method. In this study, a Markov chain Monte Carlo (MCMC) method was used to analyze statistical age models, including the central age model (CAM), the minimum age model (MAM), the maximum age model (MXAM), etc. This method was first used to obtain sampling distributions on parameters of interest in an age model using D_e distributions from individual sedimentary samples and subsequently extended to simultaneously extract age estimates from multiple samples with stratigraphic constraints. The MCMC method allows for the use of Bayesian inference to refine chronological sequences from multiple samples, including both fully and partially bleached OSL dates. This study designed easily implemented open-source numeric programs to perform MCMC sampling. Measured and simulated D_e distributions are used to validate the reliability of dose (age) estimates obtained by this method. Findings from this study demonstrate that estimates obtained by the MCMC method can be used to informatively compare results obtained by the MLE method. The application of statistical age models to multiple OSL dates with stratigraphic orders using the MCMC method may significantly improve both the precision and accuracy of burial ages.

In this study, we explored the potential of a NaI(Tl) scintillator-based gamma spectrometer for the accurate determination of burial dose rates in natural geological samples using a full spectrum analysis (FSA) approach. In this method, an iterative reweighted least-square regression is used to fit calibration standard spectra (⁴⁰K, and ²³⁸U and ²³²Th series in equilibrium) to the sample spectrum, after subtraction of an appropriate background. The resulting minimum detection limits for ⁴⁰K, ²³⁸U, and ²³²Th are 4.8, 0.4 and 0.3 Bq·kg⁻¹, respectively (for a 0.23 kg sample); this is one order of magnitude lower than those obtained with the three-window approach previously reported by us, and well below the concentrations found in most natural sediments. These improved values are also comparable to those from high-resolution HPGe gamma spectrometry. Almost all activity concentrations of ⁴⁰K, ²³⁸U, and ²³²Th from 20 measured natural samples differ by ≤5% from the high resolution spectrometry values; the average ratio of dose rates derived from our NaI(Tl) spectrometer to those from HPGe spectrometry is 0.993 ± 0.004 (n=20). We conclude that our scintillation spectrometry system employing FSA is a useful alternative laboratory method for accurate and precise determination of burial dose rates at a significantly lower cost than high resolution gamma spectrometry.

This study provides methodological aspects on the equivalent dose estimation for travertine samples, namely heated calcium carbonate, using the TL multiple-aliquot additive-dose approach. Large equivalent doses (EDs), within the range 750–1300 Gy, were calculated using the plateau method based on the NTL glow curve. Moreover, a component resolved TL glow-peak analysis was carried out, using the integrated intensity of the NTL glow peaks for the ED estimation after deconvolution based on the OTOR model. Three different TL peaks were used, termed P4, P5 and P6. The integrated intensity of TL glow peak P4 resulted in age overestimation (15–26%), compared to the age provided using the plateau method. This overestimation could be attributed to the fact that the temperature range of P4 does not coincide with the plateau region of each sample. Milder overestimation (8–14%) was noticed using the integrated intensity of TL glow peak P6, mostly due to the poor deconvolution resolution. Only the integrated intensity of TL glow peak P5 after deconvolution provides ED values compatible with those yielded using the plateau method, with good accuracy. The present study suggests not using the TL intensity (neither in terms of integrated intensity nor of peak height intensity) for ED estimation; instead it is highly recommended to use either the plateau method, or alternatively integrated intensity of TL peak P5 after deconvolution. Unfortunately, using the peak height of TL P5 is not recommended, due to overlapping with P6.

In recent years, our investigation has been centred on improving the reliability and accuracy of the ESR method applied to quartz grains. As part of this ongoing investigation, we present an intra-laboratory study to evaluate the impact of different experimental setups on the ESR measurement precision and dose evaluation for ESR dating of optically bleached quartz grains. Repeated measurements of quartz samples have been performed at CENIEH, Spain, using two different Bruker spectrometers (EMXmicro and Elexsys E500) and resonators (standard rectangular ER4102ST and cylindrical Super High QE cavities). Their performance in terms of sensitivity, measurement repeatability and dose determination are presented in this study.

This intra-laboratory work has allowed to evaluate the robustness of our protocol for ESR dating of quartz grains and to study the potential impact of different experimental setups on dose evaluation, which is essential for future standardization of the ESR dating method. Our results indicate that all the different experimental setups provide comparable precision of the ESR intensity measurements. Moreover, all the ESR dose estimates are within 1-sigma error, suggesting that it is possible to compare results obtained by different laboratories when similar analytical procedures are followed. Finally, the higher sensitivity achieved by the SHQE resonator appears to be of particular interest when dealing with samples showing low ESR signal intensities.

The E₁’ centre is one of the most common paramagnetic defects observed by electron spin resonance (ESR) in natural quartz, the formation of which is, however, quite complicated. The dose response to gamma ray irradiation of the E₁’ centre in natural quartz was systematically investigated in the present study to find that its dose response depends on the heating conditions of the sample before irradiation. The signal intensity decreases on irradiation when quartz has been heated up to 300°C, while it increases when heated above 400°C. The phenomena can be explained by the electronic processes that heating supplies electronic holes to the oxygen vacancies while gamma ray irradiation supplies electrons.

To assess if the heat-treated E₁′ centre in quartz is suitable for fluvial sediment provenance tracing, eight granitic samples from sediments and their source rocks with distinct geological ages and origins were collected for electron spin resonance (ESR) measurements. The results show that the maximum heat-treated E₁′ signal intensity of quartz in the fluvial sediments occurs upon heating at about 300°C, as previously observed in aeolian quartz. The heat-treated E₁′ signal intensity of quartz in sediment samples also shows significant correspondence to those of their source rocks as well as their formation age. We propose that the heat-treated E₁′ centre of sedimentary quartz, combined with other lithological discrimination parameters, could serve as an effective indicator for fluvial sediment provenance tracing.

We sheared simulated-quartz gouges using a low-velocity rotary shear apparatus and evaluated the relationship between electron spin resonance (ESR) intensity and displacement quantitatively considering problems of contaminants. ESR intensity of E₁’ centre increased while OHC and peroxy centre kept constant with the increasing displacement up to 1.4 m. Microstructural analysis showed grain size reduction and fracture of starting gouges; hence, the fracture can affect the change in ESR intensity. ESR measurements were also conducted for starting gouges with variable amounts of contaminants, and it was confirmed that the effect of contaminants on the change in ESR intensity was negligible. Moreover, we estimated the temperature rise by the frictional heating on the surface and between particles, and it was shown that the effect of frictional heating on ESR intensity was also negligible in our experimental condition. Therefore, we could clarify the relationship between ESR intensity and fracturing with various displacements separately from contaminants and frictional heating. The results imply that the zero-setting of ESR signals cannot occur by the fracture with low frictional heating at the shallow depth.

Carbonated rocks constitute one of the main lithologies of the southeastern Tibet area, China, a tectonically very active zone. However, due to the lack of suitable dating materials, it is difficult to carry out chronological studies of the local tectonic evolution in such carbonate areas. In the present study, electron spin resonance (ESR) method had been applied on the dating of carbonates heated during fault activity of the Lijiang-Xiaojinhe (LX) Fault, an important active fault located in the northwest of Yunnan Province. Clear displaced landforms show that the fault has undergone strong late-Quaternary activity. During the fault activity, the heat produced by friction lead to the melting of the frictional surface of the rocks, and the melting can attenuate or zero the ESR dating signal of carbonate. The aim of the present paper was to check the ability of carbonate use to chronologically identify fault activity using electron spin resonance (ESR) method. The results showed the last fault activity of the LX fault was dated by ESR about 2.0±0.2 ka ago, in agreement with historical and radiocarbon data. Hence ESR can be if necessary a practicable dating alternative method for the study of fault activity chronology in carbonate rock area.

The present study aimed at quantifying the relationship between TL and either CW-OSL or LM-OSL using commercially available magnesium oxide. The samples were bleached at two different temperatures, and a component-resolved analysis on the integrated signals was performed. According to the data of the present study, each one among the five observed LM-OSL component receives electrons from at least two different TL peaks. Two different fast OSL components were resolved in the LM-OSL curves, both accumulating electrons from all TL glow peaks with T_max>150°C. Component C₃ is very well correlated with the TL peaks at 102, 135 and 194°C, while components C₄ and C₅ are related to the TL glow peaks of 292°C, 353°C and 464°C. We note that for CW-OSL the resolution is good when two or more components differ in intensity by an order of magnitude. Blue stimulation depletes substantially the first two TL peaks but not the third peak. Substantial depletion of the high-temperature TL peaks is achieved only by using the LM-OSL configuration. The results of the present study suggest that the traps that contribute to TL and OSL are the same, despite using different recombination pathways.

The loess sediments widely distributed in the Central Shandong Mountains are sensitive records of East Asian monsoon changes for situating in a key region connected to the Eurasian Plate and the Pacific Ocean. However, the detailed processes of palaeoclimatic changes are poorly understood for the lack of high-resolution chronology. In this study, the chronology of Heishan loess palaeosol sequence in the Central Shandong Mountains is investigated using quartz SAR OSL and K-feldspar post-IR infrared (IR) stimulated luminescence (post-IR IRSL) dating method. The quartz is sensitive, fast component dominated and saturate at ∼150 Gy (∼50 ka). The measured K-feldspar pIRIR₂₉₀ D_e showed no dependency on the first IR stimulation temperature between 50°C and 260°C. The K-feldspar pIRIR₂₉₀ ages are consistent with the stratigraphy up to ∼75 ka. In establishing the chronological sequence for the study section, quartz OSL ages <50 ka and the K-feldspar pIRIR₂₉₀ ages >50 ka were selected. Derived sedimentation rates show two relatively rapid stages of ∼32.0 ± 5.5 cm/ka for the palaeosol (∼11–8 ka) and ∼54.8 ± 1.1 cm/ka for the loess (∼34–30 ka). An erosional hiatus of loess between ∼30 ka and ∼17 ka is identified. We conclude that the pIRIR₂₉₀ of loess sediments is applicable for samples during ∼8–75 ka.

To better understand the factors controlling the quartz luminescence sensitivity in loess deposits, samples from two loess sections in southern Tajikistan are investigated. Both pattern and amplitude in the variations of quartz luminescence sensitivity of these two sections are similar, showing higher values in pedocomplex units and lower values in the loess units. Similar trends of variation are found between the quartz luminescence sensitivity and climate proxies, including frequency-dependent magnetic susceptibility, median grain size and IRSL/[post-IR] OSL ratio. Laboratory experiments involving thermal activation and repeated bleaching/irradiation cycles reveal much larger sensitivity enhancement for samples with initial lower sensitivity from loess units than those from pedocomplex units with higher sensitivity. The observed systematic contrast in quartz luminescence sensitivity between the loess and pedocomplex units are interpreted as resulting from the differentiation of the weathering products from the source area and subsequent sensitization during the sedimentary transfer prior to deposition.

Lake shoreline beach ridges and their sediments have often been investigated as paleoenvironmental indicators in arid northern China. Robust chronology is crucial to utilize this archive for paleoenvironmental reconstruction and interpretation. In this study, we reported a robust chronology for the highest wave-built beach ridge around Jinchang paleolake at the northeast (NE) margin of the Tibetan Plateau, using a combined quartz and K-feldspar luminescence dating technique, together with radiocarbon dating. The consistent quartz and K-feldspar ages suggested the sufficient reset of luminescence signals before deposition for the investigated sediments. Both kinds of luminescence ages were in agreement with three independent ¹⁴C ages, further corroborating the robustness of these obtained luminescence ages. Our results demonstrated that the investigated beach ridge was formed around 8.5–6.9 ka, suggesting a distinct period of lake highstand which has been identified in other lakes nearby. This highstand event may implicate an increased regional moisture condition, which is likely caused by the increased Asian summer monsoon precipitation.

This study presents single-grain optically stimulated luminescence (OSL) results from pottery and sediments from the archaeological site “The burials in Khutag Uul Mountains (Mongolia)”. A global fitting procedure was used on a selection of single grains from pottery, D₀ values obtained were between 16 to 40 Gy and 25 to 82 Gy and the equivalent doses D_e ranged from ∼8 to 12 Gy and from 4.2 ± 0.4 Gy to 37.3 ± 2.5 Gy for pottery and sedimentary quartz, correspondingly.

For pottery, the relative spread in CAM D_e values increases as higher precision constraints are applied and lead to significant increases in the relative standard error from 2.7% to ∼7.5%. The number of accepted grains which passed acceptance criteria reduced from 180 to 65. For sedimentary quartz, there is a trend observed that both MAM D_e and FMM D_e values increase as higher precision in D_e is applied, and the number of accepted grains reduces from 146 to 53.

The detailed study of the OSL decay curves identified an ultrafast OSL component with the decay rates of 53 ± 1 s⁻¹ in addition to the fast and medium components and its effect on D_e was examined.

The residual ages and bleaching of K-feldspar post-IR IRSL (pIRIR) signals (pIR₅₀IR₁₇₀, pIR₅₀IR₂₉₀, and pIR₂₀₀IR₂₉₀) for a variety of modern sediment sources to the Bosten Lake basin in the southern Tian Shan of arid central Asia were assessed to identify the most appropriate facies to sample for ascertaining well-bleached, depositional ages associated with Quaternary paleolake development. Results indicate pIR₅₀IR₂₉₀ residual ages for pluvial fan, fluvial, and eolian sediments cluster at 40–6, 6–3, and 2–1 ka, respectively, and are depositional ages. Residual ages of pIR₂₀₀IR₂₉₀ signals are twice that of pIR₅₀IR₂₉₀ signals, while residual ages of pIR₅₀IR₁₇₀ signals are similar to that of pIR₅₀IR₂₉₀ signals for all samples. Eolian and fluvial samples show well-bleached, coarse-grained (90–125 μm) K-feldspar and poorly-bleached coarse grained K-feldspar from pluvial samples. High residual doses in fluvial and pluvial samples indicate it may not be advisable to apply pIRIR dating utilising different pIRIR signals to Holocene lacustrine samples. However, the residual ages measured for eolian deposits are small and can allow precise and robust assessment of paleolake development by targeting the K-feldspar pIR₅₀IR₁₇₀ signal to date Holocene samples and the pIR₂₀₀IR₂₉₀ and pIR₅₀IR₂₉₀ signals to date Pleistocene samples.

Wuhan area located middle Yangtze River Basin, is dominated by East Asian Monsoon. Widely developed Holocene flu-lacustrine sediments are ideal materials for the reconstruction of paleoclimate change and geo-environment evolution, for which the chronology is a key issue. In this study, 20 luminescence dating samples were collected from a flu-lacustrine sequence and the reliability of the quartz OSL dating to these samples were checked by using luminescence characteristics of dose recovery test and thermos transfer test. Our results indicate that different grain size fraction of 4∼11 μm, 38∼63 μm, and 90∼125 μm were well-bleached before burial. Dating results show that all these ages range from 0.8 ± 0.1 to 7. 9 ± 0.7 ka between 4.25 and 38.55 m, and most of them follow the stratigraphic sequence and other climatic recorder within the normal range of error. Disordered OSL ages may be caused by complicated transport-deposit processes. As a consequence, OSL dating method of SAR-SGC protocol could provide a significant chronology for Holocene flu-lacustrine sediment in large river depo-system.

There are still controversies for the lakes evolution time during late Pleistocene in arid/semiarid north China. Badain Jaran Desert (BJD) features the coexisting of modern lakes in the lowland of megadunes. Also, lots of lacustrine relics could be found distributed widely in the desert, some of them just beside the modern lakes. These lacustrine relics indicated the paleo lakes evolution and the paleo environmental changes in the desert. In this study, one 3.9 m depth lacustrine deposits section was studied in the southeastern BJD which is close to a modern lake Zongzegedan (ZZGD). The deposit ages of the section were obtained by using optical dating with both of quartz and K-feldspar grains. Optically stimulated luminescence (OSL) dating of quartz grains shows that this paleolake was appeared during 65–34 ka, which is in the Marine Isotope Stage (MIS) 3 period, without the saturation of the OSL signals. On the other hand, the high temperature infrared stimulated luminescence (pIR IRSL) dating results from K-feldspar grains show that the paleolake was existed from late MIS 5 to late MIS 4 (86–60 ka) period with also good luminescence characteristics. The further study suggested that the OSL signals from quartz grains in this section show thermal instability, which may lead to the age underestimation. So the reliable age of the existed paleolake should be obtained by using pIRIR signals from K-feldspar, indicated that the relative humid environment in the desert happened at late MIS 5. The paleolake has same position with modern lake in the desert may contain geomorphological indications.

Luminescence dating technology has been used for chronological constraints on lacustrine sediments due to the ubiquitous materials (e.g., quartz and feldspar) as dosimeters, and a relatively long dating range, compared with the commonly used radiocarbon dating method. However, quartz dating on the Tibetan Plateau may suffer from dim and unstable luminescence signals. In the current study, we investigate a lake-related outcrop from the shore of Cuoe Lake on the central Tibetan Plateau. Both coarse-grained quartz and K-feldspar fractions were extracted, and OSL and post-IR IRSL signals were measured from these fractions, respectively. Combining the stratigraphy analysis and dating results, this study shows that: (1) quartz appears to be unsuitable for dating because of very dim natural signals and even anomalous fading (average g-value: 4.30 ± 2.51 %/decade). The suitability of the applied pIRIR protocol measured at 150°C (pIRIR₁₅₀) for K-feldspar samples was confirmed by a set of luminescence tests; (2) compared with the luminescence-based chronology, the ¹⁴C age of shells from the same sediment layer yielded older age by ∼7 ka, which is likely attributed to hard water reservoir effect in Cuoe Lake; (3) the lake level reached its peak and maintained high-stand during the early Holocene (∼9.4–7.1 ka). This study highlights the applicability of K-feldspar luminescence dating when the counterpart quartz OSL is insensitive and encounters anomalous fading.

The Qaidam Basin preserves the largest Yardang field on Earth, and yardangs are intriguing landforms for studies of the paleo-environment and aeolian processes. Formation of yardangs involved both the initial lacustrine deposition and the subsequent wind-erosion processes. However, the timings of both processes in the Qaidam Basin are still controversial due to limited age data and unsuitable dating methodology. In this paper, we first compared two optical dating methods to determine the suitable one for the study area, then investigated the geomorphic processes based on the new ages. Two-step post-IR IRSL (pIRIR) and multi-elevated-temperature pIRIR (MET-pIRIR) methods of feldspar, were applied to date lacustrine sediments on the top parts of yardangs to decipher the transition time from depositional to an erosional environment. Comparisons of the two methods demonstrated that the influence from anomalous fading was very minimal thus negligible for MET-pIRIR method, as proved by the De plateau between MET-pIRIR₂₅₀ and MET-pIRIR₂₉₀; while the pIR50IR₂₅₀ signals suffered from fading obviously, which was difficult to be corrected due to the high De close to saturation. Consequently, the chronology in this study was based on the MET-pIRIR₂₅₀ method, potentially offering reliable ages of over 200 ka. Seven MET-pIRIR₂₅₀ ages of 201–336 ka suggested that a mega-Qaidam Lake (>2714 m a.s.l. on Google Earth) maintained until Marine Isotopic Stage (MIS) 7. The absence of sediments since ca. 200 ka implied wind-erosion and yardang formation since MIS6. This transition from lacustrine to a wind-erosion environment was interpreted as a response to the glacial-interglacial scale climatic changes.

The precise chronology of the fluvial terraces of the Yellow River in China is essential to understand its geomorphological evolution history. More terrace ages are needed for the correlation of the terraces along the river and the construction of the longitudinal profile. In this study, seven terraces (T1–T7) in the Heiyukou area of the Jinshaan Canyon of the river were identified and were sampled for optical dating. The reliability of the ages was evaluated on the bases of bleachability, comparison of optical ages on fine and coarse grains, stratigraphic consistency of OSL ages, age distribution and geomorphological setting. The results show that the paired T2 terrace was formed at 72 ± 3 ka, and the T4, T5 strath terraces were dated to 108 ± 4 and >141 ± 4 ka, respectively. The ages for the samples from T6 and T7 were significantly underestimated, and the ‘infinitely old’ pre-Quaternary Red-Clay sample on the T7 terrace was dated to 134 ± 6 ka. The long-term river incision rates were calculated to be <0.36, 0.34 and 0.18 mm/a for at least the past 141, 108 and 72 ka, respectively, which also reflect the uplift rates of the Ordos plateau. The implication for dating terrace deposits is that terraces should be systemically sampled and dated using both fine and coarse grain fractions. The reliability of the ages obtained for high terraces should be evaluated using a relative chronology of dated samples on a case-by-case basis, if no independent numerical age controls are available.

At the eastern tip of Anjihai anticline on the northern piedmont of Tian Shan (northwest China), deformed fluvial deposits have recorded active folding since the Pleistocene, but the absence of accurate ages makes it difficult to evaluate the anticline's shortening rate. Geological studies ascribed the fluvial strata to the early Pleistocene, which poses potential challenges for luminescence dating. In this study, multi-methods luminescence dating was applied to a fluvial sand sample taken from the sandy bed of the deformed basal strata. Single grain post-Infrared Infrared Stimulated Luminescence (pIRIR) and multiple-aliquot-regenerative (MAR) dose along with multiple-elevated-temperature pIRIR (MET-pIRIR) procedures were applied to determine the paleodose of the sample. The methodological uncertainties, such as thermal transfer and initial sensitivity change, were treated by increasing the test dose and performing dose recovery test. With consideration of the potential partial bleaching and anomalous fading, various statistical metrics were applied to the D_e values determined by using the single grain pIRIR₂₂₅, single grain pIRIR₂₉₀ and MAR-MET-pIRIR₂₉₀ signals. The minimum age model (MAM) D_e values are 11% – 17% lower than the central age model (CAM) D_e values in general, and the MAM D_e values determined by the single grain pIRIR procedures are underestimated by more than 40% when compared with those determined by MAR-MET-pIRIR₂₉₀ procedure. The MAM MAR-MET-pIRIR₂₉₀ D_e of 811 ± 44 Gy results in a burial age of 284 ka for the basal deformed fluvial strata, which is much younger than the proposed early Pleistocene age.

Optically stimulated luminescence (OSL) dating of fine-grained (4–11 μm) fluvial sediments is rarely attempted but is crucial for constraining the evolution of mud-dominated floodplains. This study investigated the applicability of OSL dating to fine-grained deposits in the Mekong River, Cambodia based on a very young (<600 yr) point-bar to riverbank succession and modern flood deposits. In succession, fine-grained quartz OSL provided the youngest ages, whereas age estimates by multi-grain sand-sized quartz OSL, and feldspar and polymineral infrared-stimulated luminescence are >200 years older than the fine-grained quartz OSL age estimates. Ages of fine-grained quartz OSL are concordant with the minimum ages obtained from the single-grain quartz OSL. These results are supported by the generally small residual doses (<0.1 Gy) measured in modern fine-grained flood-plain deposits. This indicates that fine-grained sediments in the Mekong River (Cambodia) are sufficiently bleached at deposition and can yield reliable quartz OSL ages for establishing the chronology of the floodplain. The sufficient bleaching of fine-grained quartz partly results from the long transport distance and may also occur in other large river systems.

We assessed the residual dose of K-feldspar grains from modern and Holocene beach–shoreface sands at Kujukuri, eastern Japan. Samples from the modern foreshore and shoreface (to 34 m depth) show residual doses <0.2 Gy for infrared-stimulated luminescence (IR)₅₀ measured during post-IR infrared-stimulated luminescence (pIRIR)_50/150, equivalent to potential burial age overestimation of only several decades for given dose rates. Residual doses of 1–3 Gy are retained by pIRIR_50/150, equivalent to 400–1,300 years; pIRIR_50/290 residual doses are up to 30 Gy, suggesting possible overestimation by >10,000 years. Residual doses of Holocene sands were also assessed by comparison with radiocarbon ages, revealing consistent results with modern sands. The pIRIR_50/290 results show no pronounced correlation of residual dose with water depth, except for a few samples from <5 m depth with residual doses several tens of per cent lower than those of deeper sands, suggesting that most samples were not fully bleached and that sustained subaerial sunlight bleaching diminishes the difficult-to-bleach component. Compared to the uncertainties associated with other factors, such as the fading correction, the residual doses of IR₅₀ and pIRIR_50/150 are negligible for samples older than late and early Holocene, respectively. In contrast, the residual dose of pIRIR_50/290 may lead to critical age overestimation of Late Pleistocene deposits if the residual dose is not properly corrected.

The Huxushan archaeological site in northern Hunan Province, China, was recently excavated, from which stone tools including handaxes were unearthed. The deposits of the site are chemically weathered, which makes it difficult to date the site using numerical dating techniques except for optically stimulated luminescence (OSL) method. Here, we used various luminescence procedures including single-aliquot regenerative-dose (SAR), sensitivity-corrected multiple-aliquot regenerative-dose (SMAR) and thermally transferred optically stimulated luminescence (TT-OSL) SAR procedures on fine-grained quartz, and two-step post-infrared infrared stimulated luminescence (pIRIR) and multi-elevated-temperature pIRIR (MET-pIRIR) procedures on fine polymineral fractions. The results show that the fine quartz grains have excellent luminescence properties and the quartz SAR-, SMAR- and TT-OSL ages for the samples agree with each other and in stratigraphical order except for one sample. The fine polymineral fractions exhibited relatively weak pIRIR and MET-pIRIR signals, resulting in difficulty in constructing the dose-response curve for MET-pIRIR signals and the stratigraphically inconsistent pIRIR_{(100, 275)} ages. The seven samples yielded their quartz OSL ages ranging from about 62 ka to 133 ka. The two samples from the cultural layer was dated to 78 to 92 ka using different procedures on fine quartz. However, given the systematically older pIRIR ages obtained with the fine polymineral grains for the two samples, their quartz OSL ages are considered to represent the minimal ages of this layer, and their pIRIR_{(100, 275)} ages of 118 and 110 ka represent the upper age limit, indicating that the site was occupied by hominins during Marine Isotope Stage 5.

As a daily utensil and artefact, the presence of ceramic at an archaeological site is direct evidence of human activity. While ceramics have been found at numerous sites on the Qinghai-Tibetan Plateau (QTP), most have been aged using conventional methods such as typology or radio-carbon dating of associated charcoal and bone. In this study, five sand-tempered grey ceramics from Talitaliha in the Qaidam Basin were dated using quartz and K-feldspar OSL. The reliability of the ceramic OSL ages was determined using six independent radiocarbon samples, three charcoal and three bone, from the same cultural layer. Six additional OSL ages were determined on sandy loess sediments at the Talitaliha site to provide upper and lower limits for the ceramic ages. The ceramic luminescence dating results are in good agreement with the ¹⁴C ages and are within the constraints of the stratigraphic OSL ages, suggesting that OSL dating of ceramics has great potential for archaeological research on the QTP. The determined age range for the Talitaliha site was between 3400–2800 cal BP; this fits well with Nuomuhong culture dates from other locations in the Qaidam Basin that range between 3400–2450 cal BP.

In this study, we present results of luminescence dating using CW-OSL, LM-OSL and TL on heated quartz from the archaeological and historical site in Karakorum – the ancient capital of Mongolia, to test their convergence with the age control in the form of the Karakorum inscription 1346.

The TL spectra conducted on quartz from red and grey coloured bricks appeared to be characteristic of the technological origin. Quartz TL from red bricks showed a UV emission band at ∼360 nm and a strong fast OSL component dominated signal. In contrast, blue emission detected in the TL spectra of grey coloured bricks, resulting possibly in the medium component dominated OSL signal.

Finally, OSL and TL results gave dates from 1180±70 AD to 1360±70 consistent with the expected ages.