Optically Stimulated Luminescence Research Articles

Using luminescence dating to constrain lake sediment records: A new age model for the 1.38 Ma lake Malawi drill core, Eastern Africa

The 2005 Lake Malawi deep scientific drill core is the longest and most continuous high-resolution record from the continental tropics, extending to ∼1.38 Ma. While extensive sets of paleoclimate proxy data have been generated from this core, a gap in directly dated sediment, between ∼74 ka and ∼590 ka (28–167 m below lake floor), has limited the understanding of climatic drivers in this system. Previous age models fill the gap in direct dates by tuning to the global δ18O stack and interpreting paleomagnetic excursions, but these methods and the resulting models remain disputed. We fill this gap in chronology using luminescence dating, with 31 samples collected at ∼4 m resolution in this section of the core. Luminescence dating can sometimes be limited by relatively large uncertainties (typically ∼7%) and difficulty estimating the water content history of samples. We overcome these limitations by employing a high sampling density and using the sediment record to understand changes in water content during the burial period. This yields a vastly improved and robust age model that indicates changes in sedimentation rates not discernible in prior age models.

Fading performance on optically stimulated luminescence of LiMgPO4:Tb,Sm,B

This study aimed to investigate the fading of the optically stimulated luminescence (OSL) of LiMgPO4:Tb,Sm,B. Thermoluminescence (TL) glow curves were recorded immediately and 24 h after irradiation, as well as after OSL. Peaks 2 and 3 did not contribute to the fading of the TL signal, while peak 1 was identified as the primary source of TL signal fading in LiMgPO4:Tb,Sm,B. The fading was calculated by considering the OSL signal measured immediately after irradiation as the first measurement point. About 70% of the OSL signal was measured 30 days after irradiation if the pre-heat procedure was not applied. The intensity of LiMgPO4:Tb,Sm,B remains stable at 93.1% with a preheating program of 160 °C for 30 s.

The Late Holocene deglaciation of James Ross Island, Antarctic Peninsula: OSL and 14C-dated multi-proxy sedimentary record from Monolith Lake

Lentic waterbodies provide terrestrial sedimentary archives of palaeoenvironmental change in deglaciated areas of the Antarctic. Knowledge of the long-term evolution of Antarctic palaeoenvironments affords important context to the current marked impacts of climate change in the Polar regions. Here, we present a comprehensively dated, multi-proxy sedimentary record from Monolith Lake, a distal proglacial lake in one of the largest ice-free areas of the Antarctic Peninsula region. Of the two defined sedimentary units in the cores studied, the lower Unit 1 exhibits a homogeneous composition and unvarying proxy data profiles, suggesting rapid clastic deposition under uniform, ice-proximal conditions with a sedimentation rate of ∼1 mm yr−1. 14C and optically stimulated luminescence (OSL) dating bracket the deposition interval to 1.5–2.5 ka BP, with the older age being more probable when compared to independent dating of the local deglaciation. The uppermost 11 cm of the record spans the last ∼2.2 ka BP (maximum age), suggesting a markedly decreased sedimentation rate of ∼0.05 mm yr−1 within Unit 2. Whereas Unit 1 shows only scarce evidence of biological activity, Unit 2 provides an uninterrupted record of diatoms (with 29 species recorded) and faunal subfossils, including the fairy shrimp Branchinecta gaini. Concentrations of organically-derived elements, as well as diatoms and faunal remains, are consistent, implying a gradual increase in lake productivity. These results provide an example of long-term Antarctic ‘greening’ (i.e. increasing organic productivity in terrestrial habitats) from a palaeolimnological perspective. The boundary between Units 1 and 2, therefore, marks the timing of local deglaciation at the final stages of a period of negative glacier mass balance, i.e. the Mid-Late Holocene Hypsithermal. Subsequent Neoglacial cooling is evidenced by the abated influence of glacial meltwater streams and turbidity decline linked to reduced glacier runoff, although most proxy responses mirror the natural proglacial lake ontogeny.

Luminescence properties of SrB6O10:Ce,Gd phosphor for applications in OSL dosimetry and lighting

Strontium hexaborate (SrB6O10) doped with different metals and/or lanthanides has been studied widely as the thermoluminescence (TL) dosimeter. However, there is almost no dosimetry study concerning the utility of Optically Stimulated Luminescence (OSL) on SrB6O10. This preliminary study aims to examine the luminescence properties of SrB6O10 phosphor for their application in the areas of dosimetry and lighting technologies. Undoped and doped material to get an OSL dosimeter were synthesized by incorporating the dopants Ce3+, in the range of 0.1–0.7 % wt, and Gd3+, in the range of 0.1–1 % wt into the SrB6O10 structure using the solution combustion (SCS) method. The structural and morphological characterizations were performed using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) methods, respectively. Two TL peaks of SrB6O10:Ce0.1%,Gd0.5% occurred at 70 °C and 182 °C after 1 Gy exposure to beta rays with a heating rate of 2 °C/s. The step annealing measurements were carried out to determine the traps responsible for the OSL signal. Various properties of the luminophore including dose-response and reusability were investigated using blue light stimulation. The phosphor showed a little variation of response up to 20 cycles within 2 % deviation (STD) from the first OSL readout. The OSL output within the range of 2–20 Gy was determined as linear. Radioluminescence (RL) measurement was investigated by emission in the range λem = 200–1000 nm. The parent compound displayed UV emission subdivided into UVA (315–400 nm), and UVB (280–315 nm) emissions at room temperature. The Chromaticity Coordinates (CIE) of SrB6O10:Ce0.1%,Gd0.5% were calculated as x = 0.2165, y = 0.1767. These remarkable characteristics show that, if developed, SrB6O10 could be used as an OSL dosimeter.

Optically stimulated luminescence properties of In-doped CsBr transparent ceramics

0.01, 0.1, 0.5, and 1% In-doped CsBr transparent ceramics were synthesized by the spark plasma sintering method. Their photoluminescence and optically stimulated luminescence (OSL) properties were evaluated. All the samples showed transparency with transmittances of 40–60%. Luminescence due to 3P1–1S0 transitions of In + appeared at 500 nm. OSL emission peaks were confirmed at 500 nm upon constant stimulation light at 630 nm. A 0.1% In-doped sample showed the highest OSL intensities in prepared samples and the dose-response relationship was linear from 0.01 to 1000 mGy. The spatial resolution of X-ray images was confirmed from 5.00 LP/mm by using OSL of a 0.1% In-doped sample.

Palaeoclimatic shifts in the Central Ganga Basin during the Middle- to Late Holocene: Exploring the 4.2 ka arid event and its implications in northern India

The Central Ganga Basin is one of the most densely populated regions of India. It is agriculturally diverse and contributes much to the Indian economy. The region has housed numerous ancient and mediaeval empires. This study presents a continuous record of the paleomonsoon from the Chandrika Devi lake, Lucknow district of Uttar Pradesh, India which is linked with paleo vegetational shifts over the last ~6000 years (5871–75 cal yr BP). The chronology of the lake core is based on three accelerated mass spectrometry (AMS) radiocarbon and two Optically Stimulated Luminescence (OSL) dates. The multiproxy data (grain size, major and trace element ratio, total organic carbon (TOC wt%), carbon isotopes (δ13Corg‰) and pollen), suggest that the lake was initially a part of the Gomti river that began to transform into a lake at ~5000 cal yr BP with weakening of the Indian summer monsoon (ISM) in the Central Ganga Basin. The lake formation was completed at ~4100 cal yr BP under the influence of the 4.2 ka arid event. This phase marks the beginning of human presence as well as agricultural activities in the lake region with the appearance of Cerealia pollen and other agricultural taxa. The agricultural activity surrounding the lake catchment peaked at ~3000 cal yr BP. The lake gradually shrank and became a marshy lowland at ~75 cal yr BP. Our study is significant because it is the first comprehensive multiproxy study from the Lucknow region in the Central Ganga Basin on paleomonsoonal variability and its relationship to human activity, agricultural practices during the Late-Holocene with a focus on the 4.2 Ka arid event. Also, pollen record suggests that the changes in agriculture and human activity began just after 4.2 ka arid event in the study area.

Timescales of tree‐covered island dynamics on the mixed bedrock‐alluvial anabranching Vaal River, South Africa

AbstractPrevious research on mixed bedrock‐alluvial anabranching rivers has documented how alluvial islands commonly grow under vegetation influences atop slowly eroding bedrock templates, but timescales of island dynamics remain poorly constrained. We focus on the Vaal River near Parys, South Africa, and combine field investigations, aerial image analyses and optically stimulated luminescence (OSL) dating to establish timescales of initiation, growth and erosion for nine bedrock‐cored, tree‐covered, alluvial islands. For each island, two OSL samples were collected in vertical succession from sand‐rich exposures up to 4 m in thickness to establish minimum ages for island initiation (~1802 to 243 years) and to estimate local vertical aggradation rates (~0.20 to 1.8 cm year−1). The diachronous lower ages and lack of systematic upstream‐downstream trend in island age support an interpretation of patchwork initiation, growth, and erosion of islands throughout the late Holocene. Following island initiation, vertical island aggradation occurs in association with establishment of reeds, shrubs and trees, but erosion of island margins or dissection by cross‐cutting channels also can occur. Observations during and after recent large floods (peak discharges >3000 m3 s−1) provide further insights into island dynamics, including the influence of exotic trees (e.g., Eucalyptus spp.) that have colonised many islands in the postcolonial era (last ~150 years). Our findings extend previous conceptual models by constraining timescales of island dynamics and providing new insights into island stability and longevity in mixed bedrock‐alluvial anabranching rivers. Improved communication of findings regarding island geomorphology, ecology and stability can benefit local community engagement, geo/eco‐tourism and education activities, and land use planning.

Magnetic polarity stratigraphy of quaternary sediments from Ramganga paleolake, NW Himalaya, India and its paleoenvironmental implications

Paleomagnetic records from the sediments provide the foundation for studying variations in the geomagnetic field across the geological time sacle. Here, we report a new paleomagnetic data from Quaternary sediments of Ramganga Paleolake, NW Himalaya, India, to provide more insight into the global geomagnetic excursions and paleoenvironmental implications. Paleomagnetic and rock magnetic analyses were performed on a 5 m thick vertical profile of unconsolidated sediments from the Ramganga paleolake (29°46′867″N; 79°14′043″E), located in the Lesser Himalaya at a height of 798 m. One hundred fifty oriented samples from 50 sites (10 cm intervals) were obtained from the vertical section. Extrapolating the optically stimulated luminescence (OSL) dates from literature indicates that the entire section was probably deposited between 38 and 0.8 ka. The rock magnetic data shows that the remanence is carried by a low coercivity mineral and a significant amount of a soft magnetic mineral, most likely magnetite. Virtual Geomagnetic Pole (VGP) latitudes were calculated. Plot of the VGP latitudes against the sample locations from the litho-column allows us for the construction of Magnetic Polarity Stratigraphy (MPS) column. The MPS of the Ramganga paleolake has detected three geomagnetic excursions that are correlated with the global events: the Mono Lake Event (∼28.4-25.8 ka), the Gulf of Mexico Event (∼12.5–17 ka), and the Bagwalipokar Excursion Events (15.5-14.7 ka and 8-2.85 ka) respectively. The lower and middle portion of the paleolake represents the low and high energy depositional environment during the sediment deposition due to wet and arid climatic conditions.

Heavily eroded Pleistocene landscape and site-forming processes of the Acheulean artifacts-bearing Holocene sediments, Eastern Desert, Sudan

Since the Middle Pleistocene, the Sahara region has undergone strong environmental changes resulting from climate changes. Dry periods, constituting an ecological barrier to human presence, alternated with wet periods when the Sahara area was covered with green savanna and an extensive network of watercourses, allowing the area to be occupied by hunter-gatherer groups. Responding to the Quaternary climatic changes, hominin dispersal was channeled through vegetated corridors. Such evidence for human settlements connected to Pleistocene green corridors in the Sahara region has been discovered in the research area called EDAR (Eastern Desert Atbara River). This area comprises a cluster of Acheulean and Middle Stone Age (MSA) sites discovered in the fluvial sedimentary context. This manuscript discusses the occurrence of Middle Pleistocene Acheulean artifacts in much younger sediments documented at the site EDAR 6. These Acheulean artifacts are present within thick Holocene calcareous sandy silts formed between 2.7 ka and 8.7 ka based on an optically stimulated luminescence (OSL) chronology, which is also supported by paleomagnetic analysis. The stone gravelly artifacts mantled above the eolian deposits have been known in other Paleolithic sites under the desert environment of Northern Africa. We propose that the relocation of the Palaeolithic artifacts was due to long-lasting erosional and redepositional processes affecting the Acheulean artifacts-bearing sediments since the Middle Pleistocene. We interpret that the cumulative results of the two processes, i.e., the gravel framework dilation and the gravel overpassing, allowed the stone artifacts to be exposed at the surface or incorporated in the Holocene sediment layers.

Aeolian dynamics at the northern edge of Deliblato (Banat) Sand Sea, Vojvodina, Serbia, at the time of the last deglaciation

Abstract The Deliblato (Banat) Sand Sea, which is one of the largest areas of аeolian sand in Europe, is located near the Iron Gate, which marks the crossing of the Danube River through the biggest gorge of this river. Here, Danubian alluvium has served as the sand source for the Banat Sand Sea, which was formed primarily through southeasterly (Košava) winds. Utilizing a multi-proxy approach, the objective of this study is to gain a better understanding of the environmental dynamics of the Banat Sand Sea. To achieve this goal, we conducted an analysis of an archive representing an approximately 20-m-thick dune formation on the northern edge of this dune field. Using optically stimulated luminescence (OSL) dating, we calculated aeolian sedimentation rates and dune ages. Sand was deposited here approximately between 17 ka and 13 ka. Magnetic susceptibility, grain size, and colorimetric analyses were interpreted in terms of local paleoenvironmental conditions. Calculated sedimentation rates (SR) indicate intensive aeolian deposition during the study period that range from 483 cm/ka to 502 cm/ka. We compared our data with regional and other European archives, as well as with climatic variations recorded in the Greenland ice core North Greenland Ice Core Project (NGRIP).

Fluvial landscape change in Anqing through the last glacial cycle: Implications for eustatic controls on the Yangtze River's continental-scale incision-aggradation cycles

The Yangtze River is known as the ‘mother river of China’ because it flows through the country's most densely populated and historically wealthiest regions. However, the evolution of the Yangtze River and its controls remain unclear. In this study we dated samples extracted from five bedrock-penetrated boreholes in Anqing, in the lower Yangtze River Valley. The resultant optically stimulated luminescence (OSL) and radiocarbon (14C) dates would suggest that fluvial sediments accumulated during the ∼33–44 ka and ∼11-0.2 ka periods, with extensive erosion during the >44 ka and 33-11 ka timeframes. We also reviewed data from 13 OSL and 14C dated boreholes located between the middle reaches of the Yangtze River and its estuary. The results would suggest that most of the fluvial sediments were deposited during Marine Isotope Stages (MIS) 3 and 1, with a clear erosion hiatus during the Last Glacial Maximum (LGM). Glacial-interglacial cycle-driven eustasy was the main driver of the Yangtze River's incision-aggradation process. The eustatic forcing during the glacial-interglacial cycle influenced the changes in the landscape of the Yangtze River Valley as far inland as ∼1200 km from the present-day shoreline.

OSL dating of very young aeolian sediments of NW Spain to assess dune erosion and accretion periods

Optically stimulated luminescence (OSL) ages of young coastal dune ridges have allowed getting more knowledge on the deposition, erosion and evolution of coastal dune systems in Northern Europe during historical times. However, there is a lack of knowledge of the evolution of the same systems in SW Europe. The studies published in the last years about fossil dunes in NW Spain have allowed the reconstruction of the coastal evolution of this area from the Marine Isotopic Stage (MIS 8) until the Middle Holocene. However, there is still a poor knowledge for the Late Holocene and namely the last centuries. Dating young sediments is challenging due to the low signal to noise ratio of the natural OSL signal and because young samples are very sensitive to thermal transfer or partial bleaching of the luminescence signal during transport. In the last century, erosion and accretion events are better known because remote sensing methods allowed to model some coastal dune systems. However, OSL dating has also been particularly useful in NW Europe to get a better knowledge on the coastal dune evolution. In this work, seven samples from dune ridges and a climbing dune of a coastal system in Playa de Trece (NW Spain) were dated by OSL, as they record the last accretion events occurred in the last two centuries, and above all the 20th Century. For assessing the ages we have compared the results from both parametric central age models and Bayesian statistic using R package BayLum.

Chronology of core sediments from the south coastal Bohai Sea of eastern Asia and its implications for sedimentary history

The Shandong Peninsula along the coastal Bohai Sea in China is a vast alluvial plain formed by the Yellow River. It is an ideal place for investigating the evolution of landform in a river–sea interaction area where chronology is key. However, detailed optically stimulated luminescence (OSL) chronology studies of cores are still limited and have mainly concentrated on the Yellow River Delta, while they are scarce on the south coast of the Bohai Sea. In this study 16 OSL samples were collected from the upper 32 m of core DZK01 (192 m in depth) to establish a chronological framework using quartz OSL. Results indicated that the quartz OSL ages ranged from 217 ± 19 ka to 1.63 ± 0.14 ka, and we believe they were the minimum ages when De > ca. 200 Gy owing to OSL signal saturation. Our dating results reveal two sedimentary hiatuses with age gaps of 71–37 ka and 37–9.5 ka. Holocene sediments are located above a depth of 11.8 m with an onset age of approximately 9.5 ± 0.6 ka. Based on the sedimentary facies and dating results, no transgression sediment has been observed during marine isotopic stage (MIS) 3. This sedimentary sequence pattern is consistent with global sea-level change. We also summarized the extents of three transgressions around the Bohai Sea, and found very different patterns for different part of the coasts, e.g., in the north, the west, and the south. This requires further investigation.

Luminescent properties and dosimetric behavior of Eu-ion-doped ASO4 (A = Ca, Sr, and Ba)

We investigated the luminescence properties and dosimetric behavior of Eu-ion-doped ASO4 (A = Ca, Sr, or Ba) phosphors synthesized using the coprecipitation method. Structural analysis of the phosphors was performed using X-ray diffraction patterns, which revealed that the prepared samples exhibited a pure phase with diffraction peaks matching those of undoped orthorhombic structures. The luminescence properties of the phosphors were examined by measuring photoluminescence and photoluminescence excitation spectra. We found that both Eu2+ and Eu3+ emissions were detected for A = Ba and Ca, whereas only Eu2+ emission was observed for A = Sr. Further, time-resolved photoluminescence decay curves indicate the presence of Eu2+ and Eu3+ luminescence with different lifetimes. The optically stimulated luminescence (OSL) and thermoluminescence (TL) responses of the samples were investigated. The OSL and TL responses were found to vary linearly with the irradiation dose. This study sheds light on the potential applications of Eu-ion-doped ASO4 phosphors in radiation dosimetry and optoelectronic devices.

Combined different luminescence dating approaches on fluvial gravel deposits from the southern Upper Rhine Graben

In recent years, luminescence dating has witnessed significant advancements to overcome its traditional boundaries. However, methodological challenges persist when dating high-energy fluvial gravel deposits in proglacial settings, because partial bleaching and the scarcity of sand lenses complicate luminescence age estimation through conventional approaches. To address these issues, using rock surfaces of large clasts may overcome the limited availability of sand layers in some deposits and allow clast specific assessment of luminescence signal resetting at the time of deposition through the analyses of bleaching profiles. The Hartheim gravel pit in the southern Upper Rhine Graben of southwest Germany features a sedimentary succession deposited by distal braided river meltwater streams reworked during the late Pleistocene. Different luminescence approaches have been applied to sand lenses, the sandy matrix of gravel deposits and crystalline cobbles. Quartz optically stimulated luminescence (OSL) ages range between ∼19 and 22 ka, which represents the time just after the last glaciation maximum in the region. The OSL ages of the sandy matrix of ∼24-27 ka are in an agreement with the previous estimates, as these are from a stratigraphic lower position. However, post-IR infrared stimulated luminescence (pIRIR) ages of sand layer and sandy matrix both are some 3-6 ka older than the OSL ages, despite being internally very consistent. Luminescence depth profiles show that the signal was deeply reset in some cobbles, whereas in others only the IRSL signal in the surface layer appears to have been reset. The cobble IRSL ages show a relatively large spread, and it remains uncertain, if this is caused by incomplete bleaching or it reflects dosimetric issues. Nevertheless, overall, our results underscore the potential of rock surface luminescence dating to date fluvial deposits from the Upper Rhine Graben and similar settings.

Beam quality conversion factor of BeO-OSLD for high-energy photon beams

Optically stimulated luminescence (OSL) dosimeters are used in radiotherapy. The beam quality conversion factor () of dosimeters is essential for correcting energy dependence. However, the of an OSL dosimeter using BeO (BeO-OSLD) has not yet been reported for high-energy photon beams. In this study, the of BeO-OSLD was investigated for high-energy photon beams using experiments and Monte Carlo calculations. In the experiments, was evaluated as the ratio of calibration coefficients determined using high-energy photon beams and 60Co γ-rays. Ten OSL dosimeters were used to reduce the statistical uncertainty of the determined values, and the same dosimeters were repeatedly used to obtain the data set of high-energy photon beams and 60Co γ-rays. Pre-irradiation with 10 Gy and bleaching were performed on fresh dosimeters before dosimetry to reduce the dependence of the detector response on the accumulated dose. In Monte Carlo calculations, both the absorbed dose to water and that of the BeO dosimeter for high-energy photon beams and 60Co γ-rays were calculated, and then was determined using the ratio of these values. The determined values in high-energy photon beam were 0.998 ± 0.011 and 1.021 ± 0.005 for the experiment and the calculation, respectively. These results showed that the variation in for 6 to 25 MV was negligible in practical dosimetry. This result indicates that BeO can be used to evaluate doses for different beam qualities without correcting for energy dependence.

High-resolution luminescence-dated sediment record for the last two glacial-interglacial cycles from Rodderberg, Germany

The Rodderberg Volcanic Complex (RVC) is well-known for the long climate record archived in its crater basin, which lasts for several glacial-interglacial cycles. However, a detailed chronological framework is still lacking. Here, we perform high-resolution luminescence dating on a 72.8 m-long sediment core with the optically stimulated luminescence (OSL) signal from fine-grained (4–11 μm) quartz and three kinds of post-infrared infrared (pIRIR) stimulated luminescence signals from fine-grained polymineral fractions. Together with magnetic susceptibility, grain size and quartz OSL sensitivity measurements, a numerical age framework is built for the upper half of the sediment core. Quartz OSL ages align well with pIRIR ages for the last 45 ka, but they underestimate in relation to pIRIR ages for ages beyond 45 ka. The three pIRIR signals, including the pIRIR signal at 225 °C (pIRIR225), the pulsed pIRIR signal at 150 °C (pulsed pIRIR150) and the multi-elevated-temperature pIRIR at 250 °C (MET-pIRIR250), yield consistent ages up to ca. 250 ka at a sediment depth of 37.5 m. Below that depth, dating limits of the protocols are reached. Nevertheless, our results indicate that sediments below 37.5 m predate Marine Isotope Stage (MIS) 7. Altogether, obtained ages reveal continuous dust accumulation during MIS 7 and MIS 6. One erosional event happened at the end of the Eemian (MIS 5e), which eroded the Eemian soil. The sedimentation rate during the Weichselian glacial period is tenfold lower compared to the sedimentation rate observed during MIS 7–6. This low sedimentation rate likely arises from the cessation of slope wash effects and the occurrence of various wind erosional events alternating with dust deposition as the basin is filled by dust. A notably high sedimentation rate is observed at the transition from MIS 6 to the Eemian, marked by the deposition of a 7 m-thick loess layer between 135–129 (±5) ka. This high sedimentation rate could be attributed to intensified slope wash and solifluction processes resulting from the thawing of permafrost at the time of deglaciation. Alternatively, it might be a signature of Heinrich event 11, during which strong winds brought large amounts of dust into the basin within a short time.

Des comparisons of Late Pleistocene alluvial deposits on the Coast of Galicia (NW Spain) using BayLum or Analyst-based procedures.

The coastal sedimentary record of Galicia (NW Spain) is important to study sea-level oscillations during the Late Quaternary. The alluvial deposits preserved in the Ria de Coruña and Ria de Arousa are remnants of fluvial valleys flooded by the sea during the successive Pleistocene and Holocene transgressions. A first chronological study by Optical Stimulated Luminescence (OSL)- revealed a fast-component dominated, but dim OSL signal emitted by quartz from this area. Equivalent dose distributions, as obtained with the Analyst software, yielded large overdispersion values, which were negatively correlated to the potassium concentration in the sediment, thus suggesting the influence of beta dose rate heterogeneities. Nevertheless, for most samples many aliquots were considered in saturation, leading to a palaeodose and age underestimation – regardless of the model choice for age calculation. In this paper, we present new analyses using the open-source R package BayLum, as the so-called saturated aliquots may be incorporated in age calculation. Thus, we test this model performance and more commonly used models in retrieving large doses. Then, we discuss the implications for age calculation for these continental sediments formed during the Late Pleistocene.

Dating mortars and bricks of Santalla de Bóveda Monument (Lugo, NW Spain)

Santalla de Bóveda Monument (Lugo, NW Spain) is a small semi-buried building, under the Bóveda parish church, built in the 18th century, with an apsidal quadrangular floor plan, which was divided into three naves, a small vaulted apse and a rectangular floor plan vaulted, where paintings depicting birds and plant elements have been well preserved. The monument has aroused great interest since its discovery, but its chronology and functionality has always been the subject of controversy. Several hypotheses have suggested that the monument was built in the Roman period and some others around the 5h, 8th or 9th century AD. However, any direct evidence or absolute age has been provided until today. The stratigraphic analysis of the building suggests five constructive phases. Bricks and mortars of all phases were sampling to perform absolute dating techniques and to get a precise and accurate chronology. Radiocarbon dating of mortars and Optically Stimulated Luminescence (OSL) dating of bricks and mortars have been used to this purpose. A total of 34 samples were taken, being 20 used for luminescence (mortars and quartz aggregates) and 15 used for 14C ages (charcoal fragments of lime mortars). 5 brick samples were also dated by Thermoluminescence (TL). The obtained ages have allowed, for the first time, stablishing an accurate and precise chronology being the first phase assigned to the 4th Century AD. Alterations of the building and the vault paintings were performed in the early 7th century, while the construction of the second floor and occasional repairs were performed during the 10th-12th centuries.

Chronology by luminescence and radiocarbon on core sediments from the northeastern pearl river plain and implications for delta process

Accurate dating is the basis for deciphering eustatic and climatic changes on deltaic sedimentary processes. In the Pearl River Delta (PRD) plain of south China, scarce robust chronology hinders the detailed interpretation of sedimentary history. In this study, quartz optically stimulated luminescence (OSL) (21 samples), feldspar post-IR IRSL (pIRIR) (4 samples) and radiocarbon (14C) (2 samples) dating were applied to obtain detailed chronological framework of core SXG06 (23-m long to bedrock) from the northeastern PRD. SXG06 consists an upper marine unit (M1) and a lower marine unit (M2), separated by a terrestrial unit (mottled clay, T1). For M1, quartz OSL and 14C samples yielded ages from 5.2 ± 0.3 to 0.32 ± 0.02 ka. The sample on top of T1 produced a quartz OSL age of 35 ± 2 ka. For other 12 samples in T1 and M2, quartz OSL signals reached saturation and generated minimum ages (>51 ka). For these the saturated quartz OSL samples, feldspar pIR50IR250 provides an age range of 123 ± 7–105 ± 7 ka. The compilation of all the above ages and previous sedimentology data reveals that: (1) M2 was formed during marine transgression of Marine Isotope Stage (MIS) 5; (2) A hiatus with an age gap of between ∼35 ka and ∼5 ka was observed, which might be due to the low sea level and resultant weathering scouring; (3) Initial M1 deposits from the northeastern PRD postdated the central and southern PRD by ∼3 ka, indicating delayed delta development in the northeastern PRD during the Holocene. (4) SXG06 experienced slow deposition 0.3 m/ka in ∼5–3 ka because of the coevally decreased sediment supply, followed by accelerated deposition rate of 3 m/ka after ∼3 ka associated with strengthen human activity.