Dose recovery and residual dose of quartz ESR signals using modern sediments : Implications for single aliquot ESR dating
Tsukamoto, Sumiko ; Porat, Naomi ; Ankjærgaard, Christina - \ 2017
Radiation Measurements 106 (2017). - ISSN 1350-4487 - p. 472 - 476.
Bleachability - Dose recovery - ESR - Quartz - Residual
Electron spin resonance (ESR) dating is a promising method for dating sedimentary quartz beyond a million years. Here we investigate the use of modern quartz samples with well bleached optically stimulated luminescence (OSL) signals to study the bleachability of the ESR signals, and to further check the applicability of the ESR single aliquot regenerative dose (SAR) protocol. The residual doses from five samples using both the Al- and Ti-centres were in general found to be large and, especially for the Al-centre, with a large variability. Although it is known that the Ti-centre is fully bleachable in nature, a subtraction of the residual dose using a modern analogue should be considered. Dose recovery tests were performed by using the single aliquot regenerative and added dose (SARA) method, and the dose recovery ratio (measured-to-added dose ratio) was obtained from the slope of the added vs. measured dose plot. The dose recovery ratio from the Ti-centre was satisfactory for all five samples indicating the validity of the proposed ESR SAR protocol. However, only one sample yielded a SARA plot for the Al-centre. This could be explained by the decrease in sensitivity caused by the annealing step in the SAR protocol and/or to the erroneous subtraction of the intensity of the peroxy centre, which overlaps with the Al-centre.
Time-resolved luminescence from quartz : An overview of contemporary developments and applications
Chithambo, M.L. ; Ankjærgaard, C. ; Pagonis, V. - \ 2016
Physica B: Condensed Matter 481 (2016). - ISSN 0921-4526 - p. 8 - 18.
Feldspar - Luminescence lifetimes - Quartz - Time-resolved optical stimulation
Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz-feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.
How to visualize quartz OSL signal components
Bos, Adrie J.J. ; Wallinga, Jakob - \ 2012
Radiation Measurements 47 (2012)9. - ISSN 1350-4487 - p. 752 - 758.
First-order kinetics - HM-OSL - LM-OSL - PM-OSL - Pseudo OSL signal - Quartz - Stimulation mode - Visualization
The optically stimulated luminescence (OSL) signal of natural quartz measured under constant stimulation power (CW-OSL) is a featureless decay curve where underlying components cannot be identified easily. Visual interpretation of quartz OSL signals is easier if signals are shown in spectrum-like form. This can be achieved either through ramped stimulation, or by transforming a measured CW-OSL curve into a pseudo OSL curve. We show that both give similar results, but that transformation should be preferred as CW-OSL provides best signal-to-noise ratios. We present different transformation methods to obtain pseudo OSL curves and discuss the advantages and disadvantages of each method. In addition, we show that different pseudo OSL transformations can be used to emphasize specific aspects of the OSL signal. We conclude that transformation of CW-OSL to pseudo hyperbolically modulated OSL provides the most useful visualization of the quartz fast OSL component. Pseudo parabolic modulated OSL is the transformation of choice for showing the slow component(s). The pseudo OSL curves can be used for rapid visual inspection of the relative contribution of the OSL components prior to further analysis.
Optical dating of fluvio-deltaic clastic lake-fill sediments - A feasibility study in the Holocene Rhine delta (western Netherlands)
Wallinga, Jakob ; Bos, Ingwer J. - \ 2010
Quaternary Geochronology 5 (2010)5. - ISSN 1871-1014 - p. 602 - 610.
Delta - Fluvial - Heterogeneous deposits - Holocene - Lacustrine - OSL dating - Quartz - Rhine
We test the applicability of quartz optically stimulated luminescence (OSL) dating on clastic lake sediments to investigate whether this dating method can be applied to study the timing and rate of deposition in Holocene fluvio-deltaic lakes. Our study concerns the filling of a lake by the Angstel-Vecht system, part of the Rhine delta in the western Netherlands. Age constraints are provided by radiocarbon dates on the development and abandonment of the fluvial channels debouching into the lake. Results indicate that light exposure prior to deposition and burial was sufficient to reset the OSL signal of the vast majority of the quartz grains. Special attention was given to accurate estimation of the dose rate in the laminated and bedded deposits. The OSL ages obtained are in good agreement with the age constraints, especially for the relatively coarse sediments. OSL results indicate that the filling of the lake took about 700 years, with a sedimentation rate of ~3. mm per year. This study is a demonstration of the use of OSL dating of sand-sized quartz to determine the timing and rate of sedimentation in a Holocene fluvio-deltaic environment.
Selection of integration time intervals for quartz OSL decay curves
Cunningham, Alastair C. ; Wallinga, Jakob - \ 2010
Quaternary Geochronology 5 (2010)6. - ISSN 1871-1014 - p. 657 - 666.
Channels - Early background - Integration time intervals - Luminescence dating - OSL - Partial bleaching - Quartz
In quartz optically stimulated luminescence (OSL) dating protocols, an initial integral of the OSL decay curve is used in the calculation of equivalent dose, once a background integral has been subtracted. Because the OSL signal commonly contains a number of exponentially decaying components, the exact choice of time intervals used for the initial-signal and background integrals determines the composition of the net signal. Here we investigate which combination of time intervals will produce the net signal most dominated by the fast OSL component, while keeping an acceptable level of precision. Using a three-component model of OSL decay, we show that for a specified level of precision, the net signal most dominated by the fast component can be obtained when the background integral immediately follows the initial signal and is approximately 2.5 times its length. With this 'early-background' approach, the contribution of slow components to the net signal is virtually zero. We apply our methods to four samples from relatively young deposits. Compared to the widely used 'late-background' approach, in which the background integral is taken from the last few seconds of OSL, we find less thermal transfer, less recuperation and a higher proportion of aliquots yielding an equivalent dose in agreement with expectations. We find the use of an early background to be a simple and effective way of improving the accuracy of OSL dating, and suggest is should be used in standard protocols.
Analysis of the quartz OSL decay curve by differentiation
Bos, Adrie J.J. ; Wallinga, Jakob - \ 2009
Radiation Measurements 44 (2009)5-6. - ISSN 1350-4487 - p. 588 - 593.
Exponential analysis - Numerical differentiation - OSL components - Quartz
A mathematical transformation based on differentiation is introduced that converts a Continuous Wave Optically Stimulated Luminescence (CW-OSL) decay curve composed of a number of exponentials into a spectrum like curve with different peaks. Peak areas of the transformed curve are equal to the time integrated OSL of the exponentials. It is shown that the peaks of the transformed curve are more separated then the original decay curve components. The transformation is applied to computer generated OSL curves and to measured CW-OSL decay curves of three different quartz samples. Advantages and limitations of this differentiation analysis method are discussed.
On the separation of quartz OSL signal components using different stimulation modes
Wallinga, Jakob ; Bos, Adrie J.J. ; Duller, Geoff A.T. - \ 2008
Radiation Measurements 43 (2008)2-6. - ISSN 1350-4487 - p. 742 - 747.
First-order kinetics - OSL components - Quartz - Stimulation mode
We investigate both theoretically and experimentally the effect of stimulation mode on the separation of quartz optically stimulated luminescence (OSL) components. We find that, when assuming first-order kinetics with the detrapping probability proportional to stimulation intensity, the OSL signal is a function of the cumulative stimulation energy and not affected by the stimulation mode. This is confirmed by close correspondence between continuous wave (CW), linearly modulated (LM) and hyperbolically modulated (HM) OSL data for some of the samples studied. For other samples the data obtained using LM stimulation differ from that obtained using the other stimulation modes. This may be due to a contribution to the OSL signal from feldspars, or it may indicate that the behaviour of these samples is not adequately described by first-order kinetics. We suggest that CW stimulation is the method of choice for dating purposes as it allows the fastest readout with the greatest signal-to-noise ratio, and because it has a constant background. HM stimulation provides a good alternative when higher resolution is needed for the initial part of the shine-down curve.
A modified SAR protocol for optical dating of individual grains from young quartz samples
Ballarini, M. ; Wallinga, J. ; Wintle, A.G. ; Bos, A.J.J. - \ 2007
Radiation Measurements 42 (2007)3. - ISSN 1350-4487 - p. 360 - 369.
OSL - Quartz - SAR - Single grain - Young deposits
We investigate the feasibility of a modified single-aliquot regenerative-dose (SAR) protocol for OSL dating of individual grains from young samples (< 300 years) using dose-recovery tests. Parameters such as pre-heat temperature, test- and regenerative-dose size, an additional bleaching step at high-temperature and optical stimulation time are optimised to give the highest percentage of accepted grains. The optimised protocol makes use of a 50 Gy test dose, a single regeneration dose of 5 Gy, an additional bleaching step and an optical stimulation of 10 s. This protocol is applied to two coastal-dune samples. Equivalent doses close to those obtained for multiple-grain single-aliquot measurements can be retrieved if: (1) short integration intervals (0.034 s) are used for the natural and regenerated OSL signals as well as the test-dose responses and (2) the background is estimated from the subsequent 0.034 s, and the net signals are used to determine the equivalent dose. Standard background subtraction methods lead to overestimation of the equivalent dose for these samples due to incorporation of a slow OSL component that was not completely reset at the time of burial.
A test case for anomalous fading correction in IRSL dating
Wallinga, Jakob ; Bos, Adrie J.J. ; Dorenbos, Pieter ; Murray, Andrew S. ; Schokker, Jeroen - \ 2007
Quaternary Geochronology 2 (2007)1-4. - ISSN 1871-1014 - p. 216 - 221.
Anomalous fading - Feldspar - IRSL - Luminesence dating - Quartz
Infrared-stimulated luminescence (IRSL) dating of feldspars has the potential to date deposits beyond the age range of quartz optical (OSL) dating. Successful application of feldspar IRSL dating is, however, often precluded due to anomalous-fading, the tunnelling of electrons from one defect site to another. In this paper we test procedures proposed for anomalous-fading correction by comparing feldspar IRSL and quartz OSL dating results on a suite of samples from continental deposits from the southeastern Netherlands. We find that even after anomalous-fading correction IRSL ages underestimate the burial age of the deposits and argue that this may be a consequence of a dependency of anomalous fading rate on the dose rate and on the absorbed dose.
Luminescence dating of Netherland's sediments
Wallinga, J. ; Davids, F. ; Dijkmans, J.W.A. - \ 2007
Netherlands journal of geosciences 86 (2007)3. - ISSN 0016-7746 - p. 179 - 196.
Feldspar - Luminescence dating - OSL - Quartz - Quaternary
Over 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 revity: 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.
Zeroing of the OSL signal as a function of grain size : Investigating bleaching and thermal transfer for a young fluvial sample
Truelsen, Jimi L. ; Wallinga, Jakob - \ 2003
Geochronometria 22 (2003). - ISSN 1733-8387 - p. 1 - 8.
Fluvial - Grain Size - Optical Dating - Poor Bleaching - Quartz
Previous studies have indicated that the OSL signal from coarser grain-size fractions might be more completely reset during fluvial transport. In this study we investigate whether this feature is real, or rather an artefact of thermal transfer effects that might affect finer grains more due to smaller thermal lag during heat treatment. Our experimental results obtained on three grain-size fractions (90-125, 180-212 and 425-500 µm) clearly show that better bleaching of coarser grains is not caused by differences in thermal transfer. On the basis of our results we advise selecting a coarse grain size for analysis when dating young fluvial deposits.
An automated system for the analysis of variable temperature radioluminescence
Poolton, N.R.J. ; Bulur, E. ; Wallinga, J. ; Botter-Jensen, L. ; Murray, A.S. ; Willumsen, F. - \ 2001
Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms 179 (2001)4. - ISSN 0168-583X - p. 575 - 584.
AlO:C - Luminescence dosimetry - Quartz - Radioluminescence - Thermoluminescence
Radioluminescence (RL, i.e. prompt luminescence emitted during exposure to ionizing radiation) is used for analysing luminescence emission processes and has been proposed as a method for determining received radiation doses in both natural and synthetic radiation dosimeters. We describe here an automated system capable of both multi-sample RL analysis and comparative studies using traditional thermoluminescence (TL) and optically stimulated luminescence (OSL) methods. The radioluminescence unit is intended as an attachment for the existing automated Risø TL-OSL systems; it delivers a dose rate of 4.5 Gy/min to materials such as quartz, using an 80 mCi90Sr/90Y β-source. The unit enables the measurement of RL in the temperature range 25-500°C using both continuous and pulsed radiation exposures. Measurements are fully automated, allowing up to 48 samples to be measured in any one experimental run. Results from several experiments are presented for two representative do simeters; natural quartz and artificial Al2O3:C. These experiments include investigation of the dose and temperature dependence of RL, pulsed RL, and spectrally resolved RL; comparisons with TL are also made.
Testing optically stimulated luminescence dating of sand-sized quartz and feldspar from fluvial deposits
Wallinga, J. ; Murray, A.S. ; Duller, G.A.T. ; Törnqvist, T.E. - \ 2001
Earth and Planetary Science Letters 193 (2001)3-4. - ISSN 0012-821X - p. 617 - 630.
Age - Feldspar group - Optically stimulated luminescence dating - Quartz - Stream sediments
We apply single-aliquot optically stimulated luminescence (OSL) dating to quartz- and feldspar-rich extracts from fluvial channel deposits of the Rhine-Meuse system in The Netherlands. The time of deposition of these deposits is tightly constrained by radiocarbon dating or historical sources. This allows us to compare OSL ages obtained on quartz and infrared OSL (IR-OSL) ages obtained on potassium-rich feldspar with independent ages over the range of 0.3-13 ka. We show that the quartz OSL ages are in good agreement with the expected age. Using IR-OSL dating of feldspar, we find a slight age overestimate for the youngest sample, whereas for older samples the age is significantly underestimated. We also apply OSL dating to older fluvial and estuarine channel deposits with limited independent chronological constraints. Comparison of feldspar IR-OSL ages with the quartz OSL ages up to ~200 ka shows a clear trend, where the former severely underestimates the latter. This trend is similar to that found for the samples with independent age control, indicating that the feldspar IR-OSL ages are erroneously young for the entire age range. In the youngest samples, incomplete resetting of the IR-OSL signal prior to deposition probably masks the age underestimation. We show that the IR-OSL age underestimation is partly caused by changes in trapping probability due to preheating. Correction for this phenomenon improves the IR-OSL ages slightly, but does not provide a complete solution to the discrepancy. We suggest that, in the light of the problems encountered in the IR-OSL dating of feldspar, quartz is the mineral of choice for OSL dating of these deposits. However, feldspar dating should continue to be investigated, because it has potential application to longer time scales.