Single-aliquot Regenerative-dose Method Research Articles

New chronology of K-feldspar isochron optical dating (iIRSL) in the late Pleistocene coastal aeolian deposits of Southeast China

Old red sand (ORS), which developed during the late Pleistocene, is widely distributed along the coasts of the western Pacific and Indian Ocean.The Optically Stimulated Luminescence (OSL) dating technology have primarily determined its sedimentary age. However, in tropical and subtropical regions, chemical weathering can impact the calculation of environmental dose rates, potentially leading to age biases whose magnitude remains uncertain.Recently, advance in the OSL dating technique, the new K-feldspar isochron dating method (iIRSL), have determined its depositional age. This approach effectively enhances the accuracy of age data by accounting for variations in past dose rates caused by chemical weathering and changes in water content during sample burial. This study used the iIRSL method to conduct infrared stimulated luminescence signal tests on ORS samples from the Haitan Island, south China. Five grain sizes of K-feldspar grains were extracted from each sample during experimentation. The single aliquot regenerative dose method (SAR) was utilized to determine the equivalent dose for each grain size and calculate age using the isochron method (iIRSL). Furthermore, it compared the iIRSL ages with quartz age (SAR). The results indicate that: (1) This study obtained four iIRSL ages, which are consistent with the ages obtained from quartz (SAR) within a reasonable range, ranging from 62.13 ± 4.85 to 39.44 ± 4.85 ka BP. (2) Comparison of the simulation results of different weathering degrees using the iIRSL method and K-feldspar two-step IRIR methods indicates that the iIRSL method can effectively mitigate the impact of chemical weathering on age determination, giving more reliable iIRSL ages. (3) The ORS along the southern coast of China mainly deposited during Marine Isotope Stages 5, 4, and 3, exhibiting relatively higher deposition rates during MIS 5 and MIS 3 at approximately 30 cm/ka and 15 cm/ka respectively. This suggests that the ORS was predominantly deposited during periods of elevated sea levels. However, it is important to note that the data from MIS 5 may have been influenced by the absence of samples from this particular stage and limitations in dating methods, resulting in a lower frequency-density of deposition ages during MIS 5 and creating an “illusion” of sediment interruption.

On the intrinsic accuracy and precision of the standardised growth curve (SGC) and global-SGC (gSGC) methods for equivalent dose determination: A simulation study

In optically stimulated luminescence (OSL) dating, the single aliquot regenerative-dose (SAR) method has been used extensively for determining equivalent doses (De) in quartz. A variation of the SAR method is the “standardised growth curve” (SGC) method, which has been used as an efficient procedure to save measurement time during dating studies. During the application of the SGC method one establishes the SGC and calculation of the De of an aliquot requires only measurement of the standardised natural dose signal. Recently, a “global standardised growth curve” (gSGC) method was developed as an improved version of the SGC procedure. During the application of the gSGC method, the growth curves are re-normalised using sensitivity-corrected signal corresponding to one of the regenerative doses. Subsequently the De of an aliquot is estimated using the sensitivity-corrected natural dose signal and an additional sensitivity-corrected regenerative dose signal as well as the established gSGC. In the present study, simulations are performed to assess the intrinsic accuracy and precision of the SGC and gSGC De estimates. The results of our simulations validate that the gSGC method is intrinsically more precise than the SGC method and is also more accurate for doses greater than 210 Gy. Several factors which affect the reliability of the two methods are investigated.

Optical dating of flowstone and silty carbonate-rich sediments from Panxian Dadong Cave, Guizhou, southwestern China

Panxian Dadong Cave located in the western Guizhou is a very important Paleolithic site in China. At this site bone and stone artifacts, human teeth and mammalian fossils (known as Ailuropoda-Stegodon fauna) were found, and the site was previously dated to 120–300 ka using ESR/uranium-series methods. In this study, we successfully extracted fine quartz grains from flowstone and silty carbonate-rich sediments in the excavated area. The quartz extracts displayed excellent luminescence properties, and satisfied the SAR (single-aliquot regenerative dose method) acceptance criteria. The sensitivity-corrected OSL signals are not saturated at a dose up to about 1400 Gy. The cultural unit was OSL dated to 190–300 ka, corresponding to MISs 7–8. The flowstone deposits overlying the cultural unit were determined to be 13–190 ka and the silty carbonate-rich sediments underlying the cultural unit to be 300–360 ka. The optical ages are in general agreement with the coupled ESR/U-series and U-series ages.

Single aliquot regenerative dose method for ESR dating using X-ray irradiation and preheat

Equivalent dose (De) estimations in electron spin resonance (ESR) dating have mostly been done by the multiple aliquot additive dose (MAAD) method despite disadvantages. In this study, we used X-ray irradiations and applied the single aliquot regenerative dose (SAR) technique to ESR De measurements of a volcanic quartz with independent age control. As the SAR protocol involves multiple steps of irradiations and readouts during a short period of time using a single aliquot, the thermal stabilities of the Al and Ti centres from natural and X-ray irradiated aliquots were compared by a pulse annealing test. The thermal stability of natural and regenerated ESR signals is significantly different for both Al and Ti centres and preheats are therefore considered necessary after artificial irradiations. The X-ray dose rate for quartz was calibrated using the same sample which was heated and irradiated with a known gamma dose. The SAR De values using the natural sample were obtained by means of a preheat plateau test. To check and correct for possible sensitivity change induced by the annealing used to reset the natural ESR signals, the single aliquot regeneration and added dose (SARA) method was applied. The SARA De values for the Al and Ti centres were in agreement, however, this De value overestimated the expected De from the independent age control, possibly because our sample was too old for the SARA method.

Luminescence dating studies of Yeşilova Hoyuk

Abstract Ceramic findings collected from Yeşilova Hoyuk located in Izmir were dated using the thermoluminescence dating technique. The area is of significant archaeological importance since it is the first prehistoric settlement in Izmir. Recent archeological observations suggest that human occupation of the region took place about 8500 years ago comparing to previously determined dates of 5000 years. Three samples collected from the same archaeological layer (Neolithic period) in Yeşilova Hoyuk were dated using the thermoluminescence method. Archaeological doses (AD) were obtained by single aliquot regenerative dose method (SAR) for thermoluminescence (TL) using coarse grain quartz minerals extracted from samples. Thick and thin Al2O3:C thermoluminescence dosimeters (TLD) were used to determine the annual dose rate. The archaeological doses were found to vary from 25.91±0.78 to 26.82±0.68 Gy, and the annual doses were found to be between 3.34±0.24 and 3.47±0.24 mGy/a. The ages obtained for the samples were determined to be 6000±830 BC, 5740±670 BC and 5460±740 years for samples ND1, ND2 and ND3, respectively, which supports the prediction of archeologist that the sampling layer dates from the Neolithic period.

The evolution of a terrace sequence along the Yellow River (HuangHe) in Hequ, Shanxi, China, as inferred from optical dating

Investigations of river terraces are often seriously hindered by difficulties in dating the formation of terraces using conventional and well-established methods such as 14C dating. In this paper, recently developed optical dating techniques were applied to a Yellow River terrace sequence in the Hequ area, Shanxi Province, China. Based on field investigations, four terraces were identified. Systematic sampling for optical dating was carried out on these terrace deposits. The single-aliquot regenerative-dose method was used to determine equivalent dose. By analyzing the degree of bleaching of fluvial samples, maximum and minimum optical ages were obtained for these samples. The minimum optical dates obtained are geomorphologically and stratigraphically consistent with each other, suggesting that the dates are reliable. The formation ages of the four terraces are 3.4 ∼ 10, 20 ∼ 25, ∼ 30 and ∼ 90 ka, respectively. On the basis of these optical dates, the geomorphological evolution of the terrace sequence was established, and the factors affecting the terrace development discussed.

Luminescence dating of Netherlands’ sediments

AbstractOver the last decades luminescence dating techniques have been developed that allow earth scientists to determine the time of deposition of sediments. In this contribution we review: 1) the development of the methodology; 2) tests of the reliability of luminescence dating on Netherlands’ sediments; and 3) geological applications of the method in the Netherlands. Our review shows that optically stimulated luminescence dating of quartz grains using the single aliquot regenerative dose method yields results in agreement with independent age control for deposits ranging in age from a few years up to 125 ka. Optical dating of quartz has successfully been applied to sediments from a wide range of depositional environments such as coastal dunes, cover sands, fluvial channel deposits, colluvial deposits and fimic soils. These results demonstrate that optical dating is a powerful tool to explore the natural archive of the Netherlands’ subsurface.

Implications of broad dose distributions obtained with the single-aliquot regenerative-dose method on quartz fine-grains from loess

Six samples were collected from a section of Peoria Loess in Eustis, North America, for optically stimulated luminescence (OSL) dating of quartz, and all except one (LV90) produced narrow dose distributions. A comparative study was conducted on this sample and on a ‘well-behaved’ sample (LV91), involving other dating methods and examination of the quartz OSL. These investigations revealed differences in the quartz OSL growth with dose, OSL response to thermal treatments and the range of components within the OSL signals. An ultra-fast component was found in LV90 that displayed a higher rate of sensitivity change than the fast component and this had a malign influence on the determination of the equivalent dose. The distinctive luminescence characteristics of LV90 imply either a change in wind dynamics and/or the source area for the silt.

A single-aliquot regenerative-dose method based on IR [formula omitted] bleaching of the fast OSL component in quartz

In the optically stimulated luminescence (OSL) dating of quartz, the presence of significant medium and slow components in the initial-OSL signal (first 0.8 s or so) can give rise to erroneous dose estimates. Thus it is desirable to develop a dose estimation method that is based on the OSL from the fast component alone. In this paper, the reduction of fast component OSL by high temperature infrared (IR) stimulation is investigated. It is shown that, in the temperature range from 120– 190 ∘ C , it is possible to deplete the fast component preferentially using IR stimulation. The thermal assistance energy required for IR stimulation ( 1.49 eV ; 830 nm ) of the fast component is calculated to be 0.41 ± 0.02 eV . However, the elevated temperature IRSL of quartz has a poor signal-to-noise ratio; hence a single-aliquot regenerative-dose (SAR) protocol based on a differential-OSL signal (the difference between the two short OSL signals separated by an elevated temperature IR stimulation) is proposed. The measurement conditions are optimised following examination of both the photoionisation cross-sections of the fast component for different stimulation temperatures, and possible thermally induced sensitivity changes arising from holding the samples at high temperatures for long periods ( ∼ 1500 s ). The resulting equivalent dose values, and those from a conventional SAR protocol based on the initial-OSL signal, are compared with the expected doses for several samples. We observe that for samples with relatively strong medium and slow components, the SAR protocol based on isolation of the fast component (derived by IR depletion of the OSL) gives significantly more accurate estimates than the SAR protocol using net initial OSL signals. On the other hand, accurate dose estimates are obtained from samples dominated by the fast component using both protocols. Finally, the implications are discussed for dosimetry using quartz.

Dating fluvial sediments by optically stimulated luminescence: selection of equivalent doses for age calculation

Fluvial sediments are not an ideal material for optical dating because of insufficient or/and uneven exposure to daylight prior to burial. The equivalent doses for a sample obtained using the single-aliquot regenerative-dose method usually show a large scatter which may be attributed to many factors. Here we developed a technique to evaluate the contributions from each factor. Using this technique, relatively well-bleached aliquots were identified, and the average of their equivalent doses was taken for age calculation.

Photonic dating of Holocene back-barrier coastal dunes, northern North Carolina, USA

We have made the first application of luminescence sediment dating methods to coastal dunes from the barrier-island system in North Carolina. As part of a larger study of the timing of activation and stabilization of coastal dunes of northern North Carolina and southern Virginia that employed ground-penetrating radar, trenching, 14C dating, and analysis of soils, we applied photonic dating to seven samples from four sites: Jockeys Ridge, Nags Head Woods, Penney Hill, and Run Hill. We used fine-sand-sized potassium feldspar from the four samples with sufficient feldspar concentrations, and quartz from all samples. We applied the multi-aliquot infrared-stimulated luminescence thermal-transfer-correction additive-dose (ADD), and the late-light-subtraction ADD methods to the feldspars. We applied the single-aliquot regenerative-dose (SAR) method with 470 nm stimulation to the quartz. Feldspar thermal-transfer age estimates from 5±46 a (year) to 823±56 a ( 1 o ́ ) are typically <50% the value of corresponding quartz SAR ages. On the other hand, feldspar late-subtraction age estimates agree statistically (within ±2 σ) with the quartz ages. The quartz SAR age estimates are more precise and range from 108±11 to 1232±65 a, in general agreement with stratigraphy and available 14C dates from charcoal, wood and soil organic matter. Although the age underestimation of the thermal-transfer results could be ascribed to un-corrected anomalous fading, the occurrence of more acceptable feldspar ages from the late-subtraction method suggests instead that the chosen thermal-transfer method was flawed, perhaps by choice of laboratory bleaching conditions. Quartz SAR is preferred for photonic dating in this region, because of the relative abundance of quartz, the higher precision obtainable with use of the SAR method, and the lack of a general need to correct for anomalous fading in quartz extracts. Quartz SAR dating has great potential to reveal coastal dune chronologies in the eastern USA.

Luminescence dosimetry of archaeological and ceramic samples using a single-aliquot regenerative-dose method

Red thermoluminescence (RTL) using a SAR (single-aliquot regenerative-dose) method has been applied to artificial ceramic samples to determine retrospective doses, and to estimate the naturally accumulated doses for natural quartz grains. In the RTL measurement of quartz grains, several preheating effects on equivalent doses around 200 °C were examined for extracted quartz grains from tephra (Medeshima, Miyagi). Preheating at 200 °C for 10 seconds gave better reproducibility and response than those for preheating at 80 °C for 5 minutes. The RTL/SAR method was used to quartz grain samples extracted from pottery pieces with preheating at 200 °C for 10 seconds.

Dose and dose-rate dependence of optically stimulated signals in quartz: theoretical simulations.

In a recent paper Bailey proposed a general model to describe many optically stimulated luminescence (OSL) and thermoluminescence properties of natural quartz. This model consists of five electron trapping centres and four recombination centres: one of the recombination centres is assumed to be radiative and the remaining non-radiative. This paper investigates some additional aspects of the Bailey model. Firstly, the single-aliquot regenerative-dose (SAR) method has been simulated using the model. It is shown that the simulated natural dose (2 Gy) given to the 'sample' in the simulation can be estimated to within approximately 2% using the SAR method. Furthermore, sensitivity-corrected OSL growth curves have been calculated over a dose range of 0 to 2500 Gy. Using the model, it is also demonstrated that the shape of the sensitivity-corrected OSL growth curve is independent of dose rate, for dose rates of 0.001 Gy x s(-1) and 0.1 Gy x s(-1), over a dose range of 0-500 Gy.