Thermally Transferred Optically Stimulated Luminescence Research Articles

Re-examining the earliest evidence of human presence in western Europe: New dating results from Pirro Nord (Italy)

We present the results of the first dating study of site P13 at Pirro Nord, Italy, which documents some of the earliest evidence for hominin presence in western Europe. Our multi-technique dating approach is based on a combination of palaeomagnetism, electron spin resonance (ESR), thermally-transferred optically stimulated luminescence (TT-OSL) and combined U-series/ESR applied to both fossil material and host sediment. It provides ages ranging from 627 ± 59 to 1006 ± 126 ka and clustering around 0.8 Ma. One additional fossil tooth collected from the nearby P10 site also returns an age within this range. Ordinarily, this outcome would naturally lend itself to the straightforward conclusion that Pirro Nord has a late Early Pleistocene age of ∼0.8 Ma. However, this interpretation is complicated by the fact that these numerical dating results are in contradiction with the biochronological evidence, which suggests a much older age on the order of 1.3–1.7 Ma. Consequently, we explore the various potential sources of bias that could have influenced the numerical dating methods and the biochronological inferences. In particular, the critical evaluation of the palaeomagnetic data available for various sites belonging to the younger Colle Curti Faunal Unit (FU) indicates that there is non-negligible age uncertainty on the allegedly minimum age of ∼1.1 Ma traditionally assigned to the Pirro FU. Moreover, while the combined U-series/ESR dataset could accommodate an older age for the fossil remains if uranium uptake in the dental tissues occurred relatively rapidly before the closure of the system (CSUS model), the ages obtained from the two semi-independent quartz dating methods (ESR and TT-OSL) both appear to indicate that the sediment was last exposed to sunlight about 0.8 Ma. This disparity opens up the possibility that the sediment and fossil assemblage may not be coeval. In other words, it is possible that the fossil remains may have been reworked into younger deposits that entered the karst about 0.8 Ma. Though feasible from a karst sedimentary dynamics perspective, this hypothesis is not consistent with previous taphonomic studies that indicate an absence of evidence for fossil reworking after entering the karst. At the very least, our dating results indicate that site formation processes at Pirro Nord site P13 are more complex than previously considered.

Chronological constraint of Neanderthal cultural and environmental changes in southwestern Europe: MIS 5–MIS 3 dating of the Axlor site (Biscay, Spain)

ABSTRACTThe cave site of Axlor (Biscay, Spain) preserves one of the most informative Middle Palaeolithic (MP) records for the North Atlantic Iberian region, though its age remains poorly known. Here we use single‐grain optically stimulated luminescence (OSL) and single‐grain thermally transferred OSL (TT‐OSL) dating of sediments to improve the age constraint of Axlor's MP succession (levels N–B). Our new ages are consistent with the previously publishedterminus ante quem14C ages for the site (>42.9 cal kabp), and suggest the sequence accumulated during a period of ~50 kyr. Axlor's levels N–F were deposited ~100–80 ka, probably during marine isotope stage (MIS) 5d–a, while levels D and B were deposited ~70 and ~50 ka, respectively, during MIS 4 and mid‐MIS 3. Our results indicate that major faunal and technological turnovers occurred towards the end of MIS 5, potentially coinciding with broader environmental and climatic changes. Axlor's Quina record, dated here to the onset of MIS 4, is one of the oldest in Europe. Comparisons with neighbouring sites point to complex regional chronologies and development for this particular behaviour, though detailed correlations with other MP sequences remain difficult due to their poor chronological attributes. The present study highlights the important role that single‐grain optical dating can play in elucidating the broader evolution of the MP across southwestern Europe.

Multi dating approach of long marine core sediments from the south-eastern continental shelf of Korea: Comparison of SAR OSL, TT-OSL and pIRIR dates

Marine sediments constitute important archives of past oceanic, climate, and sea-level changes. However, it is difficult to derive accurate chronological models due to the absence of long sediment cores and limitations of dating methods. To investigate the feasibility of applying optically stimulated luminescence (OSL) ages to establish high-resolution chronologies in the East Sea of Korea, we obtained three cores with lengths up to 120 m from the eastern continental shelf of Korea. Most of the core sediments were homogeneous or crudely laminated mud, with some sand and gravel bed. Multiple dating methods, including fine-grained quartz single-aliquot regenerative-dose (SAR) OSL, thermally transferred OSL (TT-OSL) from fine-grained quartz, and single-grain K-feldspar post-infrared (IR) infrared stimulated luminescence (IRSL) (pIRIR), following the above description, were applied to overcome the age limitation and create an accurate age model through cross-checking among the different dating methods. We also investigated the applicability of the standardised growth curve (SGC) to TT-OSL signals in continental shelf environments. The equivalent dose (D e ) values from the SGC were consistent with those from the SAR TT-OSL procedure, which suggests that the SGC is valid for long core sediments on the continental shelf. A detailed chronology derived from the radiocarbon, U/Th, and multiple OSL age dating methods was compared. Especially, in core 19ESDP-101, a comparison between TT-OSL ages from fine-grained quartz and pIRIR ages from coarse K-feldspar showed agreement to within 10% at most depths for which ages were measured. We demonstrated that OSL dating from long marine core sediments in a continental shelf margin environment can provide an accurate and precise chronology in undatable regions.

Development of BeO:Na,Yb,Dy ceramics for optically stimulated luminescence dosimetry

This paper presents the structural and luminescence characterization of undoped and trivalent lanthanide-doped BeO ceramics synthesized via the co-precipitation synthesis technique. Phase confirmation of the products was achieved by the x-ray diffraction (XRD) method, while the surface and elemental morphology were carried out with scanning electron microscopy (SEM)/energy dispersive spectrum (EDS) analyses. Radioluminescence (RL), Thermoluminescence (TL) and Optically stimulated luminescence (OSL) methods were utilized for the luminescence characterization. Moreover, the relationship between TL and OSL signals was investigated in-depth with three different experiments (TL after OSL, step annealing and thermally-transferred OSL (TT-OSL).The radiation sensitivity of BeO:Na5%,Yb0.2%,Dy0.01% ceramics was found to be high as a peak OSL signal of 1.3 × 104 counts/mg for 0.2 Gy beta dose. A wide green emission band between 475 and 625 nm was detected for the first time in the RL emission spectra of doped/undoped BeO ceramics. It has been found that the RL and TL emissions of BeO ceramics have partially similar luminescence mechanisms and the TL traps responsible for the ∼315 °C TL peak are the main source of OSL signals. The Tm-Tstop method, Eac-Tstop graph and deconvolution of TL glow curve have been conjunctionally used to estimate kinetic parameters of TL traps in BeO:Na5%,Yb0.2%,Dy0.01% pellets. The results demonstrate that the TL glow curve has at least five TL peaks at 172 ± 2, 223 ± 2, 316 ± 2, 356 ± 2 and 465 ± 2 °C with estimated activation energies 1.13, 1.16, 1.39, 1.41, and 1.99 eV, respectively. The dosimetric characteristics of BeO:Na5%,Yb0.2%,Dy0.01% pellets have been also performed by reusability, dose-response, and fading experiments, and the results show that the material is promising and encouraging for use in dosimetric applications.

ESR/U-series chronology of the Neanderthal occupation layers at Galería de las Estatuas (Sierra de Atapuerca, Spain)

The Galería de las Estatuas is a Mousterian site located within the Cueva Mayor-Cueva del Silo karstic system at the Sierra de Atapuerca (Burgos, Spain). This site is characterised by an important Upper Pleistocene stratigraphic sequence in which a large number of lithic artefacts exhibiting clear Mousterian affinities and a rich assemblage of faunal remains have been found. Additionally, this site has yielded a foot phalanx of a clear Neanderthal affinities and its sediment has yielded Neanderthal mitochondrial and nuclear DNA. Two test pits, GE-I and GE-II, have been excavated since 2008 which have been divided in 5 and 2 lithostratigraphical units, respectively. A minimum age of 45 ka cal BP for this site was obtained by radiocarbon dating in GE-II. This chronology was refined using single-grain Optically Stimulated Luminescence (OSL: 80–112 ka in GE-I and 70–79 ka in GE-II) and single-grain thermally transferred OSL (TT-OSL). Although in all case TT-OSL ages were systematically older than their single-grain counterparts. The detrital sequence is sealed by a flowstone whose base is dated to 53.7 ± 3.5 ka cal BP using U-series dating. In order to better constrain the age of this site, nine herbivorous teeth were collected from the whole sedimentary sequence to be dated by the ESR/U-series dating method though only seven provided modelled ages. Six of them were collected from levels 2 to 5 of the GE-I test pit while the last tooth was taken from level 2 of the GE-II test pit. Our results, ranging between 80 and 110 ka, are in agreement with those obtained by single grain TT-OSL and suggest that the sedimentological levels containing Mousterian lithic artefacts and faunal and human remains began to be deposited during the second part of the MIS5. These results fill a temporal gap in the chronology of the Atapuerca sites for which no contemporary MIS5 date was obtained until recently. • First time application of ESR/U-series dating on teeth from the Galería de las Estatuas site. • The importance to contrast the previous dates with others obtained with a different methodology. • These results fill a temporal gap in the chronology of the Atapuerca sites. • The new ESR/U-series ages confirm the Middle Palaeolithic age of this site.

San Quirce (Palencia, Spain): new chronologies for the Lower to Middle Palaeolithic transition of south‐west Europe

AbstractSan Quirce is an open‐air archaeological site situated on a fluvial terrace in the Duero basin (Palencia, northern Iberia). This paper presents new and consistent chronologies obtained for the sedimentary sequence using post‐infrared infrared stimulated luminescence (pIR‐IR) dating of K‐feldspars and single‐grain thermally transferred optically stimulated luminescence (TT‐OSL) dating of quartz. The new dating results indicate that the sequence is older than ~200 000 years and place San Quirce Level III within marine isotope stages (MIS) 8 and 7, between 274 ± 13 ka and 238 ± 13 ka. The main lithic assemblage at San Quirce comes from Level III. The predominant tool types found in this level are hammerstones, manuports and flakes, with a small proportion of cores and a significant presence of denticulates. Adaptation to local environmental conditions resulted in distinctive cultural habits, which were embedded in the cultural tradition of hominins occupying the site during the final third of the Middle Pleistocene. San Quirce preserves a simple cultural tradition that was employed by local hominins to engage in a diverse array of activities, and highlights the cultural diversity that appears to have been a characteristic feature of the Lower to Middle Palaeolithic transition 300–200 ka.

Extended-Range Luminescence Dating of Central and Eastern Amazonia Sandy Terrains

The Amazonia biome hosts upland closed and open vegetation ecosystems, in which the current biogeographical patterns relate to the evolution of the physical landscape. Therefore, understanding the origin and timing of the substrates supporting different ecosystems is indispensable for better comprehension of Amazonian biogeography. Here we used quartz optically stimulated luminescence (OSL) and thermally transferred optically stimulated luminescence (TT-OSL) for dating sandy substrates of closed and open vegetation environments in Central and Eastern Amazonia, from both outcrop and drill core samples (Autazes core: PBAT-15-43). These sandy substrates present ages ranging from 1 ka up to almost 2 Ma, that were primarily interpreted as depositional ages of fluvial terraces. Moreover, ages are discussed in terms of potential geomorphic processes leading to the formation of substrates, such as soil mixing and apparent age of quartz from the parent bedrock. The coupling between OSL and TT-OSL techniques allow us to date sedimentary deposits covering the whole Quaternary, which implies a new time window for the Amazonia history.

Thermally Transferred Optically Stimulated Luminescence, TT-OSL: a study on the responsible traps

Abstract Aim of this paper is to better investigate the Thermally Transferred Optically Stimulated Luminescence (TT-OSL) signal generated in quartz samples, both mineral quartz and quartz extracted from sediment, when they are heated after an optical bleaching. In recent years, TT-OSL has become an interesting dating technique because it can extend by an order of magnitude the age range over which OSL dating can be applied. We focused in particular on the source traps that generate this signal, studying the changes in TT-OSL due to the preheat temperature that induces the thermal transfer, and analysing the Thermoluminescence (TL) signals caused by OSL and TT-OSL measurements. By varying the preheating temperature, it was possible to identify the presence of a peak at ∼280-300°C, likely related to a trap responsible for the TT-OSL signal. A similar result was obtained by analysing the glow curves after an optical bleaching, which evidenced a peak at ∼270°C, comparable with a peak previously identified. It was also possible to highlight the fact that the OSL and TT-OSL signals are originated by different mechanisms due to the differences between the source traps responsible for them.

Incision and aggradation phases of the Amazon River in central-eastern Amazonia during the late Neogene and Quaternary

The development of the Amazon River as a transcontinental drainage has been narrated in terms of the sedimentary record in western Amazonia and in marine offshore areas. However, little is known about the landscape changes in central-eastern Amazonia, which is considered a former water divide prior to the establishment of the Amazon as a transcontinental drainage. In this study, we carried out geomorphological and sedimentary facies analyses of fluvial deposits associated with the Amazon River in central-eastern Amazonia. Additionally, extended range luminescence ages and sediment provenance data are used to help to improve the chronostratigraphic framework of the study area. Erosive scarps bound the Amazon River valley in the study area, where higher elevation upland terrains (locally called ‘terra firme’) are sustained by older and resistant bauxitic-lateritic paleosols that cap the Cretaceous sandstone bedrock. Two abandoned fluvial terraces (T3 and T2), representing lower elevation terra firme, and the active floodplain (T1), collectively record the incision and aggradation phases of the Amazon River in a NE-SW oriented valley since the Late Miocene. The T3 is intensely dissected and has weathered deposits with surface elevations between 30 and 50 m above sea level (a.s.l.). These deposits are composed of gravel with boulders, coarse sand, and locally grey mud rich in organic matter. Quartz thermally-transferred optically stimulated luminescence (TT-OSL) dating allows us to determine the oldest Quaternary ages reported for fluvial terraces associated with the Amazon River. Depositional ages for the T3 deposits range from 944 ka to 2.3 Ma. The T2 deposits form a flat area with surface elevations between 25 and 30 m a.s.l. These deposits comprise fine to medium sand interbedded with mud and locally coarse sand and mud alternations forming inclined heterolithic stratification. Feldspar post-infrared infrared (pIRIR290) luminescence ages indicate an incision and aggradation phase leading to deposition of the T2 from 557 to 140 ka. The T1 represents the active floodplain with a surface elevation lower than 25 m a.s.l. These deposits are composed of moderately to well-sorted silty fine sand and greyish mud. OSL sensitivity measurements suggest that deposits from all terraces are formed by a mixture of Andean and shield-cratonic sediments, which are similar to the sediments transported by the modern Amazon River. The fractures in the Paleozoic to Cretaceous bedrock that comprises the higher elevation terrain incised by the Amazon River in central-eastern Amazonia lead to differential fluvial erosion, shaping the current NE-SW and NW-SE valley orientation. The T3 and T2 terraces record the progressive incision of the Amazon River valley since the Late Miocene, leading to poor preservation of fluvial deposits in comparison with western Amazonia. Here in central-eastern Amazonia, fluvial activity has been locked into a narrow fluvial valley in comparison with a wide area in western Amazonia. The stratigraphic scenario with a limited accommodation space favoured the recycling of terraces within the Amazon River valley. The restricted distribution of deposits associated with the Amazon River in central-eastern Amazonia is attributed to the uplift behaviour and high erosional resistance of the Paleozoic and Mesozoic bedrock forming a high elevation plateau. During the Pleistocene, the T3, T2 and T1 deposits record at least three main phases of incision, which promoted the abandonment of floodplains and formation of new lowland terra firme areas.

Chronology of the Huxushan Paleolithic Site in South China: Inferred from Multiple Luminescence Dating Techniques

Abstract 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.

Single grain TT-OSL ages for the Earlier Stone Age site of Bestwood 1 (Northern Cape Province, South Africa)

The transition from the Earlier Stone Age (ESA) to the Middle Stone Age (MSA) in the interior of southern Africa is associated with the Fauresmith Industry. Major cultural developments found in the Fauresmith include regular use of ochre and other coloured minerals, prepared core technology including blade and point production, and the use of hafted spears. Chronological control for the Fauresmith is weak so that critical questions regarding the relationship of this industry to the evolution of modern humans remain unresolved. Here we present ages for the Bestwood 1 site, an open-air locality in the Northern Cape Province (South Africa) where an extensive Fauresmith occupation is found underlying sand deposits. Optically stimulated luminescence (OSL) was first applied to samples from the sands overlying the Bestwood 1 occupation horizon, and from the occupation horizon itself, in order to establish the chronology of the site. However, sediment mixing resulting from bioturbation processes has been observed, causing post-depositional bleaching of the majority of the grains, thus limiting the use of OSL. In addition, given the identification of the lithic assemblage to the Fauresmith, it seems likely that the sands were beyond the dating range of conventional OSL. Due to its hard-to-bleach properties, the thermally transferred-optically stimulated luminescence (TT-OSL) signal was deemed suitable for detecting the least-bleached grains. Single grain TT-OSL analyses combined with the finite mixture model (FMM) were conducted in order to isolate the oldest grains that could be contemporaneous with the time of deposition of the sediment associated with the ESA assemblage. High scattering of the equivalent doses is consistent with bioturbation processes that mixed sediment; the distribution of the equivalent dose values suggests that younger grains were incorporated into the ESA layers, thus supporting the use of the oldest component determined using the FMM to calculate the TT-OSL ages. This approach allowed us to establish the time for the Fauresmith occupation at 366 ± 32 ka, and the age of the overlying sand deposits, spanning from 350 ± 22 ka to 226 ± 13 ka.

Luminescence dating of the Jigongshan Paleolithic site in Hubei Province, southern China

The Jigongshan (JGS) Paleolithic site in the middle reaches of the Yangtze River has two different cultural layers, namely, the upper (flake-tool industry) and lower (cobble-tool industry) cultural layers. JGS site is also among the few upper Paleolithic sites in the middle reaches of the Yangtze River with an absolute age. Peking University has performed a preliminary 14C dating at the site and found that the upper culture layer is approximately 10–20 ka, whereas the lower layer is older than 50 ka. To date the lower culture layer precisely, the standard quartz single-aliquot regenerative (SAR) dose-based optically stimulated luminescence (OSL) and thermally transferred OSL (TT-OSL) methods were used in this study. Results showed that the age of the upper culture layer is approximately 23 ± 2–38 ± 3 ka, whereas that of the lower culture layer is approximately 115 ± 9–149 ± 9 ka. The 14C and OSL dating methods showed huge differences in their results for the lower culture layer. Based on our dating results, we propose that the main part of the upper culture layer corresponds to the late MIS 3 to the early MIS 2 stages during the glacial period in L1 unit in the Chinese loess sequence, whereas the lower culture layer corresponds to the late MIS 6 and the early MIS 5 stages during both glacial and interglacial periods in the upper L2 and the lower S1 units. A cultural gap of nearly 100 ka was observed between these two cultural layers; this gap is larger than what was expected.

Insights into the relationship between luminescence and ESR dating signals from Spanish sedimentary quartz samples of different geologic origins

Trapped charge dating of optically bleached quartz deposits that lie beyond the dose-saturation limits of conventional optically stimulated luminescence (OSL) has typically focused on two main techniques over the last decade: electron spin resonance (ESR) and thermally transferred optically stimulated luminescence (TT-OSL). In spite of a clear association between these two dating techniques through their shared dose rate terms, the exact relationships between the various ESR centre (i.e., Al and Ti) and TT-OSL dating signals remain largely unexplored. In this study we undertake ESR and luminescence signal comparisons on paired sedimentary quartz samples from two Middle Pleistocene Spanish archaeological sites (Porto Maior in northwest Spain and Cuesta de la Bajada in northeast Spain) to examine the empirical relationships between quartz dating signals across different geological provinces. For this purpose we undertake 3-dimensional (3D) thermoluminescence (TL) spectral measurements, single-grain TT-OSL dating and signal analyses, normalised multiple centre (MC) ESR signal characterisation (ESR intensities, signal composition, dose-response curve properties), MC ESR De evaluation, and ICP-OES analysis of quartz extracts to evaluate potential correlations between elemental impurity concentrations and Al, Li–Ti and Li–H centre signals. The ESR samples from Cuesta de la Bajada and Porto Maior display similar Al centre signal intensities and dose-response behaviour, but they exhibit major differences in their Ti centre properties. Geochemical analysis reveals that the Cuesta de la Bajada quartz extracts contain higher concentrations of Al and Ti impurities (15 and 21% higher, respectively) when compared with the Porto Maior quartz extracts. These compositional differences appear correlated with the relative Ti–H signal intensities for the two sample datasets but not with the relative Al and Ti–Li signal intensities. The luminescence characterisation comparisons reveal a higher proportion of TT-OSL-producing grains in the Cuesta de la Bajada samples (6.2% versus ~1.6% for Porto Maior), and single-grain TT-OSL signal intensities that are almost an order of magnitude higher than for the Porto Maior samples. The 3D TL spectra for the Cuesta de la Bajada quartz are dominated by two major TL peaks in the red emission band (620 nm) at 265–310 °C and 365 °C (when using a heating rate of 1 °C/s), which are up to seven times more intense than the corresponding signals observed for the Porto Maior quartz. However, no major inter-sample differences were observed in the blue and UV-blue bands of the 3D TL spectra. These contrasting luminescence characteristics may be indicative of variable signal sensitisation histories related to dissimilar sedimentary recycling or geological origins between the two sites. Our results provide a useful baseline dataset for future comparative ESR and luminescence characterisation studies, and indicate a potentially close relationship between the quartz ESR Ti centre and single-grain TT-OSL signals. There is significant potential to refine understanding of these signal relationships in the future by expanding the number, and geographic coverage, of paired ESR–luminescence comparison studies, and by incorporating comparative 3D TL spectral investigations that focus exclusively on TT-OSL-producing grains (as opposed to bulk grain populations) to better elucidate luminescence trapping and recombination characteristics.

A multi-technique dating study of two Lower Palaeolithic sites from the Cher Valley (Middle Loire Catchment, France): Lunery-la Terre-des-Sablons and Brinay-la Noira

We present the results of a new dating study carried out at Lunery-la Terre-des-Sablons (LTS) and Brinay-la Noira (BN), two key Lower Palaeolithic sites located in deposits associated to the Cher River (Middle Loire Catchment, France). These sites preserve abundant Mode 1 and Mode 2 lithic industries, and are considered as among the oldest evidence of hominin presence in Western Europe north of the 45°N latitude. Following a multi-technique approach combining electron spin resonance (ESR), single-grain thermally-transferred optically stimulated luminescence (TT-OSL) dating of quartz grains and palaeomagnetism, we obtained new chronological constraints for the sedimentary sequence, and the associated lithic assemblages, at the two sites. The new independent dating results derived from each method are consistent and in overall agreement with existing ESR and terrestrial cosmogenic nuclide (TCN) burial age estimates, except for the Lowermost Unit 3 at LTS. By integrating all of the previous and new dating results, we derive combined age estimates of 772-735 ka and 665 ± 29 ka for the fluvial sands at LTS (Unit 1) and BN, respectively. These two distinct aggradation phases may tentatively be correlated to interglacial/glacial transitions associated with Marine Isotope Stage (MIS) 19-18 for the former and MIS 17-16 for the latter.At BN, an age range of 638–676 ka may be proposed for the hominin occupation after combining numerical age results and geological evidence. This result is consistent with the initial chronology proposed by Moncel et al. (2013) [Moncel, M.H., Despriée, J., Voinchet, P., Tissoux, H., Moreno, D., Bahain, J. J., Courcimault, G., Falgueres, C. (2013). Early evidence of Acheulean settlement in north-western Europe – la Noira site, a 700 000 year-old occupation in the Centre of France. Plos One, 8(11): 1–22] and confirms that BN is among the oldest Acheulean occurrences in Western Europe. At LTS, the mean age of 710 ± 50 ka obtained for the sandy layer in Unit 3 provides a minimum age constraint for the archaeological level located below. The major sedimentary disconformity observed between the fluvial deposits and the underlying pebble layers hosting the lithic artefacts suggests that the true age of the artefacts might be significantly older, probably Early Pleistocene given their similarities with other Mode 1 assemblages identified in Western Europe. However, further refinement of the Mode 1 chronological inference at LTS remains difficult at this stage.Finally, these new dating results show the importance of using the Multiple Centre approach for ESR dating of quartz grains, and confirm the value of combining different dating methods in order to build more robust chronologies for Lower Palaeolithic sites in Europe. From a methodological point of view, the dating results presented here are especially encouraging for the reliability of the ESR method applied to optically bleached quartz grains. This is one of the very first studies demonstrating that quartz samples independently dated by two different laboratories may produce generally reproducible ESR age results.

Extended-range luminescence dating of quartz and alkali feldspar from aeolian sediments in the eastern Mediterranean

Abstract. Optically stimulated luminescence (OSL) of quartz is an established technique for dating late Pleistocene to late Holocene sediments. Unfortunately, this method is often limited to up to 100 ka (thousands of years). Recent developments in new extended-range luminescence techniques show great potential for dating older sediments of middle and even early Pleistocene age. These methods include thermally transferred OSL (TT-OSL) and violet stimulated luminescence (VSL) for quartz and post-infrared infrared stimulated luminescence (pIRIR) for feldspar. Here we investigate the luminescence behaviour of the TT-OSL, VSL, and pIRIR signals of quartz and feldspar minerals of aeolian sediments of Nilotic origin from the eastern Mediterranean. We sampled a 15 m thick sequence (Kerem Shalom) comprising sandy calcic palaeosols, which is part of a sand sheet that covers an extensive region in south-western Israel. Dose recovery and bleaching experiments under natural conditions indicated that the pIRIR250 signal is the most suitable for dating the Nilotic feldspar. Luminescence intensity profiles revealed natural saturation of the three signals at the same depth of ∼6 m, indicating that ages of samples below that depth are minimum ages. Using TT-OSL and pIRIR250, a minimum age of 715 ka for the base of the section was obtained, suggesting aeolian sand accumulation along the eastern Mediterranean coastal plain already since the early Pleistocene. Our results indicate that both TT-OSL and pIRIR250 can accurately date aeolian sediments of Nilotic origin up to 200 ka and that minimum ages can be provided for older samples up to the early Pleistocene.

A review on the OSL of BeO in light of recent discoveries: The missing piece of the puzzle?

Although BeO ceramic (Thermalox® 995, Materion Co.) is today probably the most important alternative material to widely-used Al2O3:C in optically stimulated luminescence (OSL) dosimetry, the underlying OSL mechanism in BeO is not yet well-understood and contradictions in the thermoluminescence (TL) and OSL data interpretation remain. The recent discovery of thermally transferred OSL (TT-OSL) in BeO offers a new piece to this puzzle, potentially resolving the existing contradictions. The objective of this work is to show how the discovery of the TT-OSL changes our understanding of the luminescence mechanisms in BeO, leading to a more complete model for the luminescence in this material. Previously knowledge on the TL and OSL data on BeO is briefly reviewed highlighting the existing contradictions. This is followed by an explanation of the TT-OSL in this material and how these new data leads to a more complete model for the BeO luminescence. New data are presented on the detailed charge balance to support the proposed model.

Refining the chronology of Acheulean deposits at Porto Maior in the River Miño basin (Galicia, Spain) using a comparative luminescence and ESR dating approach

Trapped charge dating of optically bleached quartz, which involves techniques such as electron spin resonance (ESR) and thermally transferred optically stimulated luminescence (TT-OSL), is increasingly being used to establish Middle and Early Pleistocene chronologies for archaeological, palaeontological and palaeoenvironmental sedimentary sequences. Comparative dating studies that make use of several independent or semi-independent radiometric techniques in tandem are an invaluable means of assessing the reliability of optically bleached quartz dating methods and ascertaining empirical relationships between different quartz dating signals. In this study, we undertake a comparative dating evaluation of single-grain TT-OSL and various ESR signals that exhibit different optical resetting properties (Al, Ti–Li and, where measurable, Ti–H centres) at the Middle Pleistocene archaeological site of Porto Maior, northwest Spain, which contains a distinctive, regionally significant Acheulean stone tool assemblage. We expand the existing chronological framework for Porto Maior using single-grain TT-OSL dating, derive combined numerical ages for individual depositional units using Bayesian modelling, and further examine the relationship between ESR and TT-OSL signals by reviewing a range of published comparative dating studies. The new single-grain TT-OSL ages obtained for unit PM3 at Porto Maior (225 ± 31 ka and 242 ± 32 ka) are in close agreement with previously published ESR Ti–Li ages for this unit (266 ± 23 ka and 279 ± 26 ka) and significantly younger than those reported for the Al centre (441 ± 75 ka and 452 ± 66 ka). Our broader comparison of published TT-OSL – ESR dating results also shows statistically significant agreement between single-grain TT-OSL and Ti–Li centre ages in other sedimentary settings, suggesting a potentially closer relationship between the TT-OSL-producing traps and the Ti–Li paramagnetic centres in quartz, rather than between the TT-OSL and Al centre signals. The Bayesian modelling results for Porto Maior enable us to refine the existing bracketing depositional age for the archaeological accumulation at Porto Maior and provide a stronger statistical foundation for chronostratigraphic correlations with other Acheulean archaeological deposits found in the Miño River basin. The Bayesian model indicates that the entire Porto Maior sedimentary sequence was deposited between 312.6 ± 32.6 ka and 18.8 ± 7.7 ka, and that the in situ large cutting tool assemblage from level PM4 most likely accumulated during Marine Isotope Stage 7 (mean depositional age = 210.7 ± 24.7 ka). The results of this study reinforce the usefulness of applying the multiple centre (MC) ESR dating approach in many dating contexts, and demonstrate the value of undertaking comparisons between semi-independent quartz dating signals in order to maximise the reliability of ESR and single-grain TT-OSL quartz chronologies.

LumReader: Designing your luminescence experiment with R

During the last decades, luminescence dating has entered a phase of diversification. This evolution is strongly linked to a series of technical advances, including but not limited to the improvement of EMCCD cameras and the use of violet and yellow LEDs. New measurement techniques have been developed, such as post infra-red infra-red stimulated luminescence (postIR-IRSL) measurement protocols and thermally-transferred OSL (TT-OSL), and the luminescence properties of new materials, such as gypsum and apatite, have been reinvestigated.The appropriate configuration of detection equipment is key to the design of new experimental investigations. The R-package LumReader has been designed to simulate both the detection properties of luminescence readers and the emission properties of materials. It allows optimisation of the experimental detection window for a given filter and detector (PMT or EMCCD camera) combination through comparison of the detection window, the stimulation signal and the luminescence emission of the studied material. With the development of a reference database and its flexibility for accommodating user defined functions, this package will allow the spectral information of any luminescence experiment to be simulated, also facilitating experimental design.

New Chronology and Stratigraphy for Kathu Pan 6, South Africa

Kathu Pan 6 (Northern Cape Province) is an open-air site exposed by sinkhole activity that includes a Middle Stone Age Howiesons Poort (HP) component in a stratigraphic sequence that also includes Later Stone Age, early Middle Stone Age, and Earlier Stone Age (Fauresmith) assemblages. Here, we present the dating of the Kathu Pan 6 sequence using multiple luminescence signals: optically stimulated luminescence (blue OSL) and thermally transferred OSL (TT-OSL) on quartz; and the infrared stimulated luminescence (IRSL) post IR-IR290 signal on potassium feldspar. The results obtained from analyses of different minerals and signals for the archaeological deposits do not always conform but the quartz OSL provides the most accurate set of ages for the HP at KP6 (between 100 ± 6 and 74 ± 5 ka). This age range places the KP6 HP earlier than any of the scenarios considered plausible by Jacobs and Roberts (Journal of Human Evolution, 107, 1–13 2017) but fits well with the extended duration for the HP at Diepkloof proposed by Tribolo et al. (Journal of Archaeological Science, 36(3) 730–39 2009) and promoted by Feathers (Journal of Archaeological Science, 63, 164–174 2017). Two OSL ages bracket the Later Stone Age Wilton industry at KP6, placing it between 5.7 ± 0.3 ka and 2.3 ± 0.1 ka. These fit with known ages for the Wilton and place the KP6 occupation contemporary with Strata 4c–3b at Wonderwerk Cave.

Characterization of the thermally transferred optically stimulated luminescence (TT-OSL) of BeO

The objective of this work was to characterize more in depth the newly discovered thermally transferred optically stimulated luminescence (TT-OSL) of BeO. The studies include a more detailed investigation of the pre-heating temperature and time required to induce the TT-OSL signal; the reproducibility, additivity, and stability of the TT-OSL signal at room temperature and under ambient light exposure; the TT-OSL response to high doses (up to 25 Gy); and the possible recuperation of the OSL signal at room temperature. The results indicate that the TT-OSL is maximum for a pre-heating to 260 °C, if a heating rate of 5 °C/s is used. The TT-OSL decreases with readouts (pre-heating plus OSL readout), indicating depletion of the source of trapped charges. Sensitivity changes are observed in both OSL and TT-OSL signals to the same extend. Furthermore, it was demonstrated that the TT-OSL is additive: the TT-OSL is proportional to the total dose delivered to the detector, whereas the OSL signal is proportional to the dose since the last bleaching. This relationship holds up to ∼5 Gy; above this dose, the TT-OSL starts to saturate. The kinetics of the TT-OSL signal with pre-heating temperature and duration is consistent with a simplified model in which charges from an optically insensitive (or “difficult to bleach”) trap are transferred to an optically sensitive trap, both having similar thermal stabilities with a difference in activation energy of the order of 0.1 eV. The TT-OSL signal is stable in the dark up to the maximum duration investigated here (50 days), decaying slowly under exposure to ambient light. Furthermore, we report evidence of recuperation of the OSL signal at room temperature, which may be caused by a similar process as the one responsible for the TT-OSL signal. The results have obvious implications for practical dosimetry using BeO, including the possibility of re-estimating the doses if the detectors are accidently exposed to light, the possibility to check if the detectors have been exposed to light, the potential recuperation of OSL signal at room temperature and its influence on dosimetry if the detectors have been exposed to high doses, or the potential to use the shape of the OSL curve or the ratio between the OSL and TT-OSL signals for linear energy transfer estimation in ion beam dosimetry.