On the applicability of post-IR IRSL dating to Japanese loess

Recent work on infrared stimulated luminescence (IRSL) dating has focussed on finding and testing signals which show less or negligible fading. IRSL signals measured at elevated temperature following IR stimulation at 50°C (post-IR IRSL) have been shown to be much more stable than the low temperature IRSL signal and seem to have considerable potential for dating. For Early Pleistocene samples of both European and Chinese loess natural post-IR IRSL signals lying in the saturation region of the laboratory dose response curve have been observed; this suggests that there is no significant fading in nature. As a contribution to the further testing of post-IR IRSL dating, we have used 18 samples from two Japanese loess profiles for which quartz OSL and tephra ages up to 600 ka provide age control. After a preheat of 320°C (60 s), the polymineral fine grains (4–11 μm) were bleached with IR at 50°C (200 s) and the IRSL was subsequently measured at 290°C for 200 s. In general, the fading uncorrected post-IR IRSL ages agree with both the quartz OSL and the tephra ages. We conclude that the post-IR IRSL signal from these samples does not fade significantly and allows precise and accurate age determinations on these sediments.     

The D e (T,t) plot: A straightforward self-diagnose tool for post-IR IRSL dating procedures

This study presents a new self-diagnose method for the recently developed post-IR infrared stimulated luminescence (pIRIR) dating protocols. This criterion studies the dependence of equivalent dose (D _e) on measurement-temperature (T) and time (t), by applying the D _e (t) analysis to the IRLS and pIRIR signals measured under different temperatures, and combines these D _e (t) plots into one, so-called the D _e (T, t) plot. The pattern of the D _e (T, t) plot is shown to be affected by anomalous fading, partial bleaching and non-bleachable signal. A D _e plateau can be achieved in the D _e (T, t) plot only when the effects of these factors are insignificant. Therefore, this plot can be used as a self-diagnose tool for the validity of pIRIR results. The D _e (T, t) analysis has been applied to four recently developed pIRIR protocols, using aeolian samples with different ages. The results show that this self-diagnose tool can be applied to different pIRIR protocols for validating the pIRIR dating results and evaluating the pIRIR measurement conditions.     

IRSL and post-IR IRSL residual doses recorded in modern dust samples from the Chinese Loess Plateau

Using a set of modern/young (0 to about 200 years old) dust samples collected from the Chinese Loess Plateau the bleachability of IRSL measured at 50°C (IR₅₀) and post-IR₅₀ elevated temperature IRSL (measured at 225°C and at 290°C) is investigated by measuring the apparent (residual) doses recorded by these signals. Doses recorded by quartz OSL are used as a reference. Allowing for differences in dose rates it seems that both IRSL and post-IR IRSL signals yield residual doses that are significantly larger than the doses measured in quartz. These residual doses can be largely explained by thermal transfer caused by preheating. Nevertheless, we advise against the use of a low temperature preheat (<200°C) with IR₅₀ to date loess samples because, as has been reported before, the signal appears to be thermally unstable. In general, we conclude that it may not be advisable to apply post-IR IRSL dating to Chinese loess samples where residuals of up to ∼20 Gy are a significant fraction of the total dose. However, these residuals quickly become unimportant when dating older samples, and this is the age range in which post-IR IRSL dating is likely to be most useful.     

Review and assessment of the potential of post-IR IRSL dating methods to circumvent the problem of anomalous fading in feldspar luminescence

Quartz has been the main mineral used for optically stimulated luminescence (OSL) dating of sediments over the last decade. The quartz OSL signal, however, has been shown to saturate at relatively low doses of ～200–400 Gy, making it difficult to be used for dating beyond about 200 thou-sand years (ka), unless the environmental dose rate is low. The infrared stimulated luminescence (IRSL) from feldspars has been shown to continue to grow to higher dose levels than quartz OSL. The application of IRSL dating of feldspars, however, has long been hampered by the anomalous fading effect. Recent progress in understanding anomalous fading of the infrared stimulated luminescence (IRSL) signals in potassium-feldspar has led to the development of post-IR IRSL (pIRIR) protocols and also a multiple elevated temperature (MET) stimulation (MET-pIRIR) protocol. These procedures have raised the prospect of isolating a non-fading IRSL component for dating Quaternary deposits containing feldspars. In this study, we review the recent progress made on (1) overcoming anomalous fading of feldspar, and (2) the development of pIRIR dating techniques for feldspar. The potential and problems associated with these methods are discussed.     

Performance of different luminescence approaches for the dating of known-age glaciofluvial deposits from northern Switzerland

Luminescence properties of two samples taken from sand lenses in proglacial outwash de-posits of a piedmont glacier that reached the Swiss midlands during the Last Glacial Maximum are investigated in detail. Deconvolution of CW-OSL decay curves shows that the fast component dominates the OSL signal of quartz. The chemistry of single feldspar grains, in particular the K content in different grains, is determined using wavelength dispersive spectrometry (electron microprobe), revealing an average 12.9 wt.% K of the grains contributing to the IRSL signal. D _e distributions are investigated in order to gain insights into partial bleaching, and agreement is found for quartz OSL and feldspar IR₅₀ and pIRIR₂₂₅ ages for small aliquots and single grains when applying the Minimum Age Model. These ages are also consistent with independent age control. For one sample, ages determined using the Central Age Model result in highly overestimated ages for both feldspar and quartz.     

Comparison of three K-feldspar luminescence dating methods for Holocene samples

The luminescence dating of the K-feldspar fraction is an alternative way for samples that cannot yield reasonable equivalent dose (D_e) from quartz fraction with very weak luminescence signal. For testing the reliability of the infrared stimulated luminescence (IRSL) dating of K-feldspar, luminescence dating was applied to quartz and K-feldspar fractions respectively for several Holocene samples in this study. K-feldspar apparent ages using routine single aliquot regenerative-dose (SAR) protocol, K-feldspar ages using g value correction method and ages from isochron dating method were compared with quartz ages. It is found that the g value correction method cannot give reliable ages due to the large errors induced during measurements. The isochron dating method is effective to the sample with problematically external dose rate. However, isochron dating may introduce a relatively greater error during grain sizes — D_e curve fitting, therefore this method could obtain low-resolution ages for Holocene samples. Even K-feldspar apparent age from routine SAR protocol is relatively younger by about 10% than the quartz age, it still could establish reasonable chronological framework for Holocene samples.     

Shifting social networks along the Nile: Middle Holocene ceramic assemblages from Sai Island, Sudan

During the middle Holocene, profound changes in environment, economy, and social relations laid the foundations for the emergence of Africa’s earliest polities: the Egyptian Old Kingdom and the Kerma state. Regional shifts in economy and society may be reflected in local changes in patterning of ceramic production and exchange. Analysis of two pottery assemblages from Sai Island, north Sudan, reveals dramatic shifts in the scale of cultural spheres and the nature of cross-cultural interaction between 5000 BC (Khartoum Variant) and 2600 BC (Pre-Kerma). Near-sedentary Khartoum Variant hunter–gatherers at site 8-B-10C participated in a longstanding cultural sphere that extended far into the Sahara, but were beginning to focus more tightly on resources by the Nile. By Pre-Kerma times, Sai occupants familiar with animal husbandry started to use southwest Asian plant domesticates; they began to experiment with large-scale storage facilities and engage in long-distance trade along the Nile, outside of their own cultural boundaries. Beyond a shift in axes for contact from east–west to north–south, these changes signal progressive geographic and temporal compression of cultural entities, amidst accelerating processes of economic innovation and social change that finally culminated in the polities of Egypt and Kerma.     

Luminescence dating of young coastal deposits from New Zealand using feldspar

A new measurement protocol has been tested on K-feldspars from Whanganui Inlet and Parengarenga Harbour, New Zealand. A Single Aliquot Regenerative (SAR) dose protocol, using two successive infrared (IR) stimulations (post-IR IR SAR protocol) is setup for these young (<1000 years) coastal sediments. Significant anomalous fading (g _2days =7 %/decade) is observed using the conventional IR signal measured at 50°C. In contrast, the fading rate of the IR signal measured at elevated temperature (150°C) after the IR stimulation at 50°C (a post-IR IR signal) is not significant (g _2days ≤ 1 %/decade). Surprisingly low residual infrared stimulated luminescence (IRSL) signals were observed for a surface sample, suggesting that accurate ages as young as ∼50 years can be obtained for these recent deposits. IRSL ages ranging between 48±6 years and 1050±50 years are obtained from six samples, indicating that sediment accumulation has occurred at the two sites during the last millennia, despite a falling trend in relative sea-level in Whanganui Inlet and a stable relative sea-level at Parengarenga Harbour.     

New radiometric ages for the Early Upper Palaeolithic type locality of Brno-Bohunice (Czech Republic): comparison of OSL,IRSL, TL and C dating results

New radiometric data are reported from the recent excavation of the type locality of the Early Upper Palaeolithic entity of the Bohunician. Recently obtained radiocarbon (¹⁴C) data on charcoal are compared with new Optically Stimulated Luminescence (OSL) dating of sediment. OSL ages were determined on sediment from the archaeological occupation at Brno-Bohunice, as well as from the over- and underlying loessic sediments. Multiple techniques were applied, which all gave congruent results. While a dual protocol (post IR-OSL) failed the quality criteria tests, ages were obtained by Multiple-Aliquot-Additive-Dose (MAAD) on polymineral material and Single-Aliquot-Regeneration (SAR) on fine grain quartz extract as well as on polymineral material. Fading tests show significant loss of Infrared Stimulated Luminescence (IRSL) after storage for 3 and 12 months for one sample, but little or no fading for others. The resulting (uncorrected) age estimates are smaller than those on quartz by OSL methods. The latter are considered to be more reliable estimates of the sedimentation age of these deposits. The measured OSL doses do not show a simple distribution and the lowest 5% was used for age calculation to represent the most likely sedimentation age. The quartz from the loess overlying the archaeological layer is OSL dated to 30.9 ± 3.1 ka, while the sediment for the paleosol which contains the archaeological layer gave an age of 58.7 ± 5.8 ka. The attribution of this paleosol to the Hengelo interstadial is therefore questionable. However, if the Hengelo interstadial is correlated with the Dansgaard/Oeschger (D/O) event 12, statistical agreement within 2-σ is achieved. The OSL result for the archaeological layer is in accordance with a weighted average TL date on heated flint artifacts of 48.2 ± 1.9 ka from this layer as well as calibrated radiocarbon data (CalPal Hulu 2007) from nearby locations. However, radiocarbon data on charcoal samples obtained during excavation at Brno-Bohunice 2002 provide age estimates between 30 and 40 ka ¹⁴C-years, which translate to approximately (33) 35–44 ka on the calendric time scale according to the Hulu 2007 model. For the underlying loess a depositional age of 104.3 ± 10.6 ka was obtained by OSL. The presented OSL ages indicate that a simple correlation of soil sequences between sites within a region has to be verified by chronometric dating.     

Adaptation and foraging from the Terminal Pleistocene to the Early Holocene: Excavation at Bubog on Ilin Island,Philippines

Abstract

The recently discovered human remains from Callao Cave, northern Luzon, Philippines securely date the migration of hominins into the Philippines to ca. 70 kya (thousands of years ago). The direct route to reach Luzon from the Asian mainland is via Borneo, Palawan, through Mindoro and into Luzon. Our research focuses on Mindoro Island as a potential stepping stone to the main Philippine Archipelago. While Palawan and Luzon have produced evidence for early human occupation, no systematic research on the prehistory of Mindoro has been conducted until now. We report on recent archaeological investigations at the Bubog rockshelter sites on the small island of Ilin just off the coast of Mindoro. The excavations produced evidence of stratified sequences of human habitation at the two rockshelter sites in the form of dense shell middens that date to ca. 11 kya onwards. They provide direct evidence on how variability in landscape formation, sea levels, and landmass during the terminal Pleistocene and early Holocene influenced the behavior of early human populations. Numerous species of molluscs were recorded and provisional results indicate variations in the invertebrate faunas throughout the stratigraphic sequences, resulting from sea level rise and the establishment of coral reefs between Ilin and Mindoro at the end of the Pleistocene. Our results contribute substantially to our understanding of the processes of human island adaptation, complement ongoing research into Island Southeast Asia’s paleogeography, and enhance current knowledge of prehistoric subsistence strategies across the region.     

Testing the standardized growth curve (SGC) to OSL dating coastal sediments from the south Bohai Sea, China

It has been suggested that the standardized growth curve (SGC) method can be used to accurately determinate equivalent dose (D_e) and reduce measurement time. However, different opinions regarding the applicability of the SGC method exist. In this paper, we evaluated quartz OSL SGCs of marine and coastal sediments of different grain sizes and different cores in the south Bohai Sea in China, and tested their applicability to the determination of D_e values. Our results suggested as follows: (1) The SGC method is applicable to both multiple- and single-aliquot regenerative-dose (MAR and SAR) protocols of OSL dating and efficiently provides reliable estimates of D_e. (2) Finesand quartz of different palaeodoses showed highly similar dose-response curves and an SGC was developed, but old samples using the SGC method have large uncertainties. (3) For coarse-silt quartz, two different types of dose-response curves were recorded: low-dose (≤60Gy) and high-dose (≥100Gy). The growth curves of low-dose quartz were similar to each other, facilitating the use of SGC in D_e estimations, but errors tended to be larger than those obtained in the SAR method. For high-dose (100–300Gy) quartz, the SGC was also found to be reliable, but there was large uncertainty in D_e (>300Gy) estimation. We suggest that SGC could be employed for the dating of marine and coastal sediments dating using either MAR or SAR OSL protocol and either fine-silt, coarse-silt or fine-sand quartz.     

Residual doses and sensitivity change of post IR IRSL signals from potassium feldspar under different bleaching conditions

The residual doses and sensitivity change for potassium-rich feldspar (K-feldspar) have been studied using the post-infrared infrared stimulated luminescence (pIRIR) and multi-elevated-temperature post-IR IRSL (MET-pIRIR) protocols. Laboratory simulated poorly-bleached and well-bleached samples were those K-feldspar grains bleached using a solar simulator for 10 minutes and 8 hours, respectively. The residual doses rise with stimulation temperature and time. The poorly-bleached sample has larger residual doses than the well-bleached sample, especially at high stimulation temperatures. The high-temperature pIRIR signals contain a large amount of hard-to-bleach signals. A decrease of luminescence sensitivity was observed after conducting a high-temperature-treatment in the measurement cycles. The sensitivity decreases significantly between the first and the second cycle. The extent of decrease in sensitivity shows a clear temperature trend. The higher the stimulation temperature of pIRIR signals is, the larger the sensitivity decreases. This decrease is more severe for the poorly-bleached sample than for the well-bleached sample, and could possibly lead to problems in sensitivity correction.     

Holocene sediments of the Ustka Cliff (Northern Poland) in view of radiometric dating

The cliff in Ustka is an active one. The area is one of the most eroded sea shores of the Polish coast. The Ustka Cliff mainly consists of Holocene sandy deposits, but its basis is built of glacial till and clay. Field search allowed to recognize the structure and sedimentary conditions of Holocene deposits exposed in the cliff. A comparison of dating results obtained for fossil soils and peat as well as aeolian deposits, using ¹⁴C and TL methods, respectively, with available literature records is presented. The evaluation of results obtained allowed to define three main dune-forming phases for the first time for this part of the Polish coast. During the research studies new data on the processes and environmental conditions was gained and the development of structure of the area during the last 10 thousand years was reconstructed. The analysis of available data from other sections of the southern Baltic coast shows that results obtained are age similar to those determined for the ?eba Spit. The research is part of a project concerning the geomorphology of the Ustka Bay.     

Red abalone collecting and marine water temperature during the Middle Holocene occupation of Santa Cruz Island,California

Oxygen isotope values derived from prehistoric mussel (Mytilus californianus) shell calcite are used to determine whether sea-surface temperatures in the vicinity of the Punta Arena site (CA-SCRI-109) on Santa Cruz Island, California, were cooler than present between 6300 and 5300 cal BP. This site and others in the western sector of the island dating to this period are distinctive because of the presence of large red abalone (Haliotis rufescens) shells, a species that historically has been subtidal around Santa Cruz and the other northern Channel Islands. Comparison of temperature values derived from archaeological shells with those from modern mussel shells, along with water temperatures derived from satellites, indicates that waters were cooler during the 6300 to 5300 cal BP period. These results are consistent with a previous study and support the interpretation that collection of red abalone during the 6300–5300 cal BP period was partly the result of cooler water temperatures that made this large mollusk more available to foragers in the intertidal or shallow subtidal zone.     

Thermoluminescence (TL) dating of ancient Syrian pottery from six different archaeological sites

Syrian archaeological pottery sherds were collected for TL dating from six different archaeological sites named Al-Shermanieh, Tell Serah, Der Al-Hajar (south of Damascus), Tell Al-Shekdakah, Tell Al-Souwirieh (east of Damascus) and Khurbet Al-Kulieh (south west of Damascus). The samples were prepared by fine grain technique and the annual dose for each sample (pottery sherds and soil sample) was measured using an alpha spectrometer system for uranium and thorium contribution as well as with atomic absorption spectrometry for the potassium contents. The mean ages were found to be 5500 ± 150 years, 2950 ± 50 years, 1200 ± 50 years, 1300 ± 150 years, 3300 ± 100 years and 3400 ± 200 years for the examined pottery from the sites Al-Shermanieh, Tell Serah, Der Al-Hajar, Tell Al-Shekdakah, Tell Al-Souwirieh and Khurbet Al-Kulieh, respectively. The results were in good agreement with the ages estimated by archaeologists except for one sample which belongs to Der Al-Hjar site.     

Late Holocene Historical Ecology: The Timing of Vertebrate Extirpation on Crooked Island,Commonwealth of The Bahamas

We report eight new accelerator-mass spectrometer (AMS) radiocarbon (¹⁴C) dates performed directly on individual bones of extirpated species from Crooked Island, The Bahamas. Three dates from the hutia (Geocapromys ingrahami), recovered from a culturally derived bone assemblage in McKay's Bluff Cave (site CR-5), all broadly overlap from AD 1450 to 1620, which encompasses the time of first European contact with the Lucayan on Crooked Island (AD 1492). Marine fish and hutia dominate the bone assemblage at McKay's Bluff Cave, shedding light on vertebrate consumption by the Lucayans just before their demise. A fourth AMS ¹⁴C date on a hutia bone, from a non-cultural surface context in Crossbed Cave (site CR-25), is similar (AD 1465 to 1645) to those from McKay's Bluff Cave. From Pittstown Landing (site CR-14), an open coastal archaeological site, a femur of the Cuban crocodile (Crocodylus rhombifer) yielded an AMS ¹⁴C date of AD ～1050–1250, which is early in the Lucayan cultural sequence. From a humerus in a non-cultural surface context in 1702 Cave (site CR-26), we document survival of the Cuban crocodile on Crooked Island until AD ～1300–1400, which is several hundred years later than the well-documented extinction of Cuban crocodiles on Abaco in the northern Bahamas. We lack a clear explanation of why Cuban crocodiles likely survived longer on Crooked Island than on a larger Bahamian island such as Abaco. One AMS ¹⁴C date on Crooked Island's extinct, undescribed species of tortoise (Chelonoidis sp.) from 1702 Cave is BC 790 to 540 (2740 to 2490 cal BP), which is ～1500–1700 years prior to human arrival. A second AMS ¹⁴C date, on a fibula of this tortoise from McKay's Bluff Cave, is AD 1025 to 1165, thereby demonstrating survival of this extinct species into the period of human occupation.     

Late Holocene Neotropical agricultural landscapes: phytolith and stable carbon isotope analysis of raised fields from French Guianan coastal savannahs

This paper summarizes phytolith analyses from four pre-Columbian agricultural raised-field sites of the coastal savannahs of French Guiana—Savane Grand Macoua, Piliwa, Bois Diable and K-VIII—and carbon isotope analyses from the first-named site. The combined phytolith and ¹³C isotope analyses evidence the transformation of the landscape from a relatively homogeneous wetland vegetation comprised of a mixture of C4 and C3 plants (the latter including Cyperaceae and other herbaceous monocots such as Marantaceae and Heliconia, Oryzoideae grasses, and other plants typical of frequently flooded areas) to the construction of raised fields that were dominated by C4 plants (maize and other Panicoideae grasses). Our analysis proves the utility of phytoliths for tracing the agricultural history of landscapes, showing that, as in other parts of the Central and South American lowlands, maize (Zea mays) was one important crop cultivated in raised fields. We also estimated the productivity of raised-field agriculture, showing that in combination with other subsistence activities, it certainly had the capacity to sustain sizeable populations.