Constraints on the precision of SAR in equivalent dose estimations close to saturation in quartz

Difficulties in evaluating accurate equivalent doses for Late Quaternary sediments from the south coasts of Greece arose in the course of SAR measurements. Large scatter among apparent equivalent doses perplexed the evaluation of accurate mean estimates in circumstances where very large doses were involved. Besides, dose recovery experiments revealed that when intersection of the natural signal occurs onto the saturating segment of the growth curve, a distinct relationship between D_e and growth curve shape occurs. At very low slope angles, SAR tends to overestimate the recovered dose. The mechanism which controls the spread in equivalent dose estimation is investigated.     

Construction of a quartz OSL standardised growth curve (SGC) for aeolian samples from the Horqin dunefield in northeastern China

It has been suggested that the standardised growth curve (SGC) method can be used to de-terminate D_e accurately and reduce the measurement time. However, different opinions regarding the applicability of the SGC method exist. In this paper, we report the construction of quartz OSL SGC for 35 aeolian samples from different parts of the Horqin dunefield in northeastern China, and then test their applicability for D_e determination. Our results suggest that: 1) up to a regeneration dose of 80 Gy, the SGC of the Horqin dunefield can be fitted using the exponential plus linear equation, with the r² value of 0.97, and all the regeneration dose points closely stick to the fitting line, implying that all samples share a very similar dose-response curve; 2) for samples with Des ranging from 1 to 50 Gy, the ratios of SAR D_e to SGC D_e fall within the range of 0.9–1.1, and the average ratio of SAR D_e to SGC D_e is 1.01±0.01, close to unity. Therefore, the construction of SGC is correct, and the SGC is an effective procedure for accurate D_e determination for samples from the study area.     

Geoarchaeological studies on Roman time harbour sediments in Cologne — comparison of different OSL dating techniques

Due to the construction of a new North-South subway in Cologne, Roman time harbour sediments were exposed and were sampled for luminescence dating. A very good independent age control was given by the precise knowledge of the chronology of Roman activity and by radiocarbon ages of charcoal samples. Hence, different methodological approaches within luminescence dating were applied for Holocene heterogeneously bleached fluvial samples and were compared to the known ages. For one sample, optically stimulated luminescence (OSL) dating was applied to coarse-grained quartz using a single aliquot regenerative-dose (SAR) protocol. After D_e-measurements, different statistical approaches were tested (i.e. arithmetic mean, median, minimum age model, finite mixture model, leading edge method and the Fuchs and Lang approach). It is demonstrated that the Fuchs and Lang approach along with the leading edge method yielded the best matching OSL ages with respect to the known ages.     

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.     

The North Dvina river delta development over the Holocene: Geochronology and palaeoenvironment

In this paper, a detailed overview of the Holocene evolution of the North Dvina river (ND) delta (southern White Sea) is presented; it is based on radiocarbon dating, geomorphological and other field surveys, and plant macrofossil and palynological data. We have identified three main stages of the delta evolution: estuary erosional (Allerød — 5700 cal BC), lagoon or tidal-marsh (5700 cal BC — 3700 cal BC) and fan-delta accumulative (3700 cal BC — present). These stages are correlated with local climatic curves, sea level changes, glacioisostatic raise curve and Baltic Sea stages. A variety of landforms has been identified and dated within the delta. These results help to explain the spatial and temporal patterns in the prehistoric human occupation of this area.     

Mesopleistocene loess deposits in the Mamalyha 2 profile of Ukraine — interlaboratory comparison of the thermoluminescence dating results

The history of the interlaboratory comparison of TL dating results in Poland started in the 1980s. At that time the Lublin, Warsaw and Silesian laboratories made the first attempts at TL dating of the same loess samples from the Odonów profile. However, the cooperation ceased for many years due to great differences in the obtained TL age estimates. The next interlaboratory comparisons were made in the years 2000–2009 for the loess samples from several Polish (Dybawka, Tarnawce, Dankowice, Biały Kościół) and Ukrainian (Boyanychi, Halych, Velykyj Hlybochok, Yezupil) profiles. Most of the compared dates, obtained for the loess deposits from the Upper Pleistocene and younger part of the Middle Pleistocene, were consistent. This encouraged us to undertake the Gdańsk-Lublin interlaboratory cooperation in dating of 200-700 ka old loess deposits. Nine samples were taken from the Ukrainian profile Mamalyha 2 in 2009 for this purpose. The TL dating results indicate that comparable dates are obtained in two laboratories for loess deposits younger than 300 ka BP. The TL signal obtained in the Gdańsk laboratory for the samples older than 300 ka BP was saturated so such samples should not be dated by the multi-aliquot regeneration method. The results obtained in the Lublin laboratory for these deposits (489–682 ka) confirm that it is possible to date loess deposits older than 500 ka. It probably results from the use of total-bleach method with preheating at 160°C for the equivalent dose determination.     

Thermoluminescence as a technique for determining the nature and history of small solar system particles

The thermoluminescence phenomenon has been used for pottery dating and radiation dosimetry for sixty years and for forty years has been applied to the study of meteorites, being successful in quantifying metamorphic histories and providing new insights into terrestrial age and orbits. Here we review some of the fundamental properties of thermoluminescence with particular focus on the study of small extraterrestrial particles. We suggest that natural TL data can be used to identify the burial and release history of cometary particles and that induced TL measurements can provide in-sights into the mineralogy of particles (even when largely amorphous) and the metamorphic history of those particles. We illustrate the use of TL to study small particles by describing recent studies on micrometeorites and 10–100 μm fragments taken from the matrix of a meteorite Semarkona which is type 3.0 ordinary chondrite.     

Potential geoarchaeological sites for luminescence dating in the Ganga Bhagirathi-Hugli delta,west Bengal,India

Archaeological studies in the upper and lower part of the Ganga-Bhaghrathi-Hugli delta were taken up to understand the nature of site formation and human adaptation in a dynamic fluvial zone. This aspect has been neglected in Indian archaeology. However archaeological dating using typological information, has an error margin of a couple of centuries and hence, is of limited use. We suggest that high resolution chronology using Optically Stimulated Luminescence (OSL) and radiocarbon dating can be quite effective in the study of archaeology and human environment relationship in the Ganga-Brahmaputra Delta (GBD).     

Dendrochronological and radiocarbon dating of subfossil wood from the Morava River basin

The paper deals with dendrochronological and radiocarbon dating of subfossil trunks found in the basin of the Morava River. The research into subfossil trunks had been conducted in the Czech Republic in the past but the research stopped in 2001. 160 records of measurements of subfossil, predominantly oak trunk samples, are preserved from that time. Three years ago the research was reopened and again the most trunks were found in the basin of the Morava River. 92 samples of oak trunks and 7 samples of other tree species (poplar, elm, maple, beech) were taken from selected sites. The samples were processed in compliance with the standard dendrochronological methodology. To date the samples, Czech, Austrian, Polish and German standard chronologies were used. In cases when the dendrochronological dating was unsuccessful, the samples were sent for radiocarbon dating. In total, 35 samples were dated, mainly by the radiocarbon method. Subfossil trunks from gravel pit Tovačov were dated and classified into 4 different periods, the oldest being from 2780–2190 BC. In Osek nad Bečvou, the samples were taken from two sites. Whereas from the 4 trunks taken in the river channel each was from a different period, the trunks from the gravel pit come from 981–1015 AD. The trunks found in the Morava River basin near Strážnice were dated to the 10^th–15^th century. In the future, we expect to extend the amount of the acquired samples with the aim to create a link to the existing standard chronology or to create a long floating average treering curve.