Luminescence age modeling of variably-bleached sediment : Model selection and input
Chamberlain, Elizabeth L. ; Wallinga, Jakob ; Shen, Zhixiong - \ 2018
Radiation Measurements 120 (2018). - ISSN 1350-4487 - p. 221 - 227.
Bleaching - Luminescence dating - Overdispersion - Quartz sand - Residual dose
Optically stimulated luminescence (OSL) dating of heterogeneously-bleached sediment by means of a minimum age model requires the input of a ‘sigma_b’ (σb) value describing the overdispersion of the single-aliquot De distribution expected for a well-bleached sample. We propose that σb and associated uncertainty can be accurately determined if a large dataset of De distributions is available and includes well-bleached samples. Our approach applies the bootstrapped Minimum Age Model (bootMAM) to a dataset of overdispersions in De distributions, to obtain quantitative estimates of σb. Corrections are made for constant-diameter aliquots of different grain sizes, based on the published dependency of overdispersion on the number of grains per aliquot. These adapted σb values are then input to bootMAM to obtain robust paleodoses for the samples. We test the sensitivity of paleodose to σb and we demonstrate that with correct σb, identical paleodoses are obtained using bootMAM and the Central Age Model on samples judged to be well-bleached. We conclude that for large datasets consisting of well- and heterogeneously-bleached samples, appropriate σb values can be obtained from the data, and that bootMAM can be applied to all samples within this dataset.
Violet stimulated luminescence dating of quartz from Luochuan (Chinese loess plateau) : Agreement with independent chronology up to ∼600 ka
Ankjærgaard, C. ; Guralnik, B. ; Buylaert, J.P. ; Reimann, T. ; Yi, S.W. ; Wallinga, J. - \ 2016
Quaternary Geochronology 34 (2016). - ISSN 1871-1014 - p. 33 - 46.
Chinese loess plateau - Luminescence dating - Luochuan - Natural dose response curve - Quaternary - Violet stimulated luminescence (VSL)
Luminescence dating at the Luochuan loess type (China) section is at present limited to ∼0.1 Ma using quartz blue light stimulated luminescence (BLSL), but can be extended back in time to ∼0.5 Ma by resorting to the more developmental post-infrared infrared stimulated luminescence (post-IR IRSL) and thermally transferred OSL (TT-OSL) signals. Since both the latter are associated with systematic uncertainties due to the potential (a)-thermal instability of these signals, a search continues for alternative, and demonstrably stable luminescence signals that can cover the entire Quaternary timescale. Here we explore the violet stimulated luminescence (VSL) signal at the Luochuan section, which provides a continuous archive of homogenous sediment with favourable luminescence characteristics and a solid independent age framework. By testing several VSL protocols and their associated performance, we demonstrate that the Multi-Aliquot Additive-Dose (MAAD) protocol produces a VSL chronology at Luochuan which is in agreement with independent ages up to ∼0.6 Ma. For a more representative environmental dose rate of ∼2 Gy/ka (∼35% lower than at Luochuan), the documented range of MAAD-VSL sensitivity (200-1800 Gy) would correspond to the ability to date sediment up to ∼1 Ma back in time, offering a remarkable advance over existing methods.
Sedimentary architecture and chronostratigraphy of a late Quaternary incised-valley fill : A case study of the late Middle and Late Pleistocene Rhine system in the Netherlands
Peeters, J. ; Busschers, F.S. ; Stouthamer, E. ; Bosch, J.H.A. ; Berg, M.W. Van den; Wallinga, J. ; Versendaal, A.J. ; Bunnik, F.P.M. ; Middelkoop, H. - \ 2016
Quaternary Science Reviews 131 (2016). - ISSN 0277-3791 - p. 211 - 236.
Delta - Eemian interglacial - Estuary - Glacio-isostasy - Incised-valley - Luminescence dating - Palaeogeography - Preservation - Sea level
This paper describes the sedimentary architecture, chronostratigraphy and palaeogeography of the late Middle and Late Pleistocene (Marine Isotope Stage/MIS 6-2) incised Rhine-valley fill in the central Netherlands based on six geological transects, luminescence dating, biostratigraphical data and a 3D geological model. The incised-valley fill consists of a ca. 50 m thick and 10-20 km wide sand-dominated succession and includes a well-developed sequence dating from the Last Interglacial: known as the Eemian in northwest Europe. The lower part of the valley fill contains coarse-grained fluvio-glacial and fluvial Rhine sediments that were deposited under Late Saalian (MIS 6) cold-climatic periglacial conditions and during the transition into the warm Eemian interglacial (MIS 5e-d). This unit is overlain by fine-grained fresh-water flood-basin deposits, which are transgressed by a fine-grained estuarine unit that formed during marine high-stand. This ca. 10 m thick sequence reflects gradual drowning of the Eemian interglacial fluvial Rhine system and transformation into an estuary due to relative sea-level rise. The chronological data suggests a delay in timing of regional Eemian interglacial transgression and sea-level high-stand of several thousand years, when compared to eustatic sea-level. As a result of this glacio-isostatic controlled delay, formation of the interglacial lower deltaic system took only place for a relative short period of time: progradation was therefore limited. During the cooler Weichselian Early Glacial period (MIS 5d-a) deposition of deltaic sediments continued and extensive westward progradation of the Rhine system occurred. Major parts of the Eemian and Weichselian Early Glacial deposits were eroded and buried as a result of sea-level lowering and climate cooling during the early Middle Weichselian (MIS 4-3). Near complete sedimentary preservation occurred along the margins of the incised valley allowing the detailed reconstruction presented here.
Late Pleistocene to Holocene alluvial tableland formation in an intra-mountainous basin in a tectonically active mountain belt - A case study in the Puli Basin, central Taiwan
Tseng, Chia Han ; Lüthgens, Christopher ; Tsukamoto, Sumiko ; Reimann, Tony ; Frechen, Manfred ; Böse, Margot - \ 2016
Quaternary Science Reviews 132 (2016). - ISSN 0277-3791 - p. 26 - 39.
Intra-mountainous Puli Basin - Luminescence dating - River and valley development - Tableland - Tectonic vs. climatic forcing
The morphology in Taiwan is a product of high tectonic activity at the convergent margin and East Asian monsoon climate. Tablelands are prominent geomorphic features in the Puli Basin in central Taiwan. These tablelands provide an archive to understand links between past climatic evolution and tectonic events resulting in the formation of the present-day landforms. To establish a geochronological framework for the alluvium underlying the tablelands in the Puli Basin, optically stimulated luminescence dating was applied to obtain burial ages. The numerical data indicate an accumulation phase of alluvial fans in the Late Pleistocene to Early Holocene transition. The study area in the Taomi River catchment, an obvious longer precursor of the Taomi River, originating from west of the Yuchih Basin, transported the sediments forming the present-day southern tablelands. During the Pleistocene-Holocene transition, the climate changed to wetter and warmer conditions, so that slope processes might have changed and an increasing transport in the fluvial system was stimulated. Fluvial and fan terraces in other river catchments in Taiwan also indicate a period of increased fluvial transport and deposition. A geomorphic evolution model in the Puli Basin is reconstructed on the basis of the chronological framework and of sedimentological features. Fluvial processes controlled by climatic change and accompanied by tectonic activities have created the diverse topography in the Puli Basin.
Validating post IR-IRSL dating on K-feldspars through comparison with quartz OSL ages
Kars, R.H. ; Busschers, F.S. ; Wallinga, J. - \ 2012
Quaternary Geochronology 12 (2012). - ISSN 1871-1014 - p. 74 - 86.
Feldspar - Luminescence dating - OSL - Post IR-IRSL - Quaternary - Sediments
Recent developments have opened up the possibilities of using potassium feldspar for dating Pleistocene sediments; a stable (less-fading) part of the infrared stimulated luminescence (IRSL) signal can be selected by largely depleting the unstable part of the IR signal, using a combination of thermal and IR stimulation: post IR-IRSL dating (pIR-IRSL).This study aims to test the validity of pIR-IRSL dating on feldspars. We obtained pIR-IRSL ages on a large suite of samples from several locations in the Netherlands area, covering a wide range of depositional environments and ages. Age control was provided by quartz optically stimulated luminescence (OSL) ages on the same samples; these ages were shown to accord with geological age constraints. Comparison with IRSL ages enabled us to evaluate the improvement that pIR-IRSL dating provides over conventional IRSL methods.The majority of feldspar ages obtained with pIR-IRSL showed good agreement with both the quartz OSL ages and the geological age constraints. Our study demonstrates that pIR-IRSL dating is more robust than conventional IRSL and should be the method of choice in feldspar luminescence dating of Pleistocene sediments.
Expectations of scatter in equivalent-dose distributions when using multi-grain aliquots for osl dating
Cunningham, Alastair C. ; Wallinga, Jakob ; Minderhoud, Philip S.J. - \ 2011
Geochronometria 38 (2011)4. - ISSN 1733-8387 - p. 424 - 431.
Ali-quot size - Luminescence dating - MAM - Minimum-age model - OSL - Overdispersion - Partial bleaching
In the OSL dating of sediment, the scatter in equivalent dose (D e) between grains is almost always larger than would be expected due to counting statistics alone. Some scatter may be caused by insufficient (partial) bleaching of some of the grains prior to deposition. In order to date partially bleached sediment, it is essential to estimate the amount of scatter caused by other processes (e.g. grain-to-grain variability in the natural dose rate). Measurements of such scatter are performed at the single-grain level; by contrast, most OSL dating is performed on multi-grain subsamples, for which grain-to-grain scatter is reduced through averaging. Here we provide a model for estimating the expected scatter (i.e. excluding that caused by partial bleaching) for multi-grain aliquots. The model requires as input the single-grain sensitivity distribu-tion, the number of grains in the sub-samples, and the expected scatter at the single-grain level, all of which can be estimated to an adequate degree. The model compares well with measured values of scatter in De, determined using aliquots of various sizes, and can be used to help produce a minimum-age De from multi-grain subsamples that is consistent with single-grain data.
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.
Optically stimulated luminescence dating of young quartz using the fast component
Cunningham, Alastair C. ; Wallinga, Jakob - \ 2009
Radiation Measurements 44 (2009)5-6. - ISSN 1350-4487 - p. 423 - 428.
Curve fitting - Deconvolution - Fast component - Luminescence dating - OSL dating
We have attempted to isolate the fast component of the quartz optically stimulated luminescence (OSL) signal using a curve-fitting procedure. By pre-determining the decay constants, the procedure is simple enough to be scripted, allowing a large number of aliquots to be processed. A Monte Carlo error routine is used, in which simulated decay curves are fitted with several exponentials, which vary in their decay rates according to the measured distributions of fast and medium component decay rates. The derived error term is closely related to the intensity of the fast component signal, but is also influenced by the degree of similarity between the equivalent doses of the fast and medium OSL components. There are potential advantages in using this procedure to date both well-bleached and partially bleached quartz, of any depositional age.
A new approach towards anomalous fading correction for feldspar IRSL dating - tests on samples in field saturation
Kars, R.H. ; Wallinga, J. ; Cohen, K.M. - \ 2008
Radiation Measurements 43 (2008)2-6. - ISSN 1350-4487 - p. 786 - 790.
Fading correction - Luminescence dating - Quantum mechanical tunnelling
Anomalous fading of the feldspar infrared stimulated luminescence (IRSL) signal hampers possibilities of using feldspar IRSL to obtain burial ages for sediments beyond the dating range of quartz optically stimulated luminescence. Here, we propose a new approach to quantify anomalous fading of the feldspar IRSL signal over geological burial times based on laboratory fading experiments. The approach builds on the description of the quantum mechanical tunnelling process recently proposed by Huntley [2006. An explanation of the power-law decay of luminescence. J. Phys. Condensed Matter 18, 1359-1365]. We show that our methods allow the construction of un-faded and natural IRSL dose-response curves as well as anomalous fading rates in field saturation. The predicted level of field saturation closely approximates the measured saturation level for five samples from fluvial deposits (Lower Rhine) known to be older than 1 Ma. The modelled anomalous fading rate in field saturation (13.4% per decade) is close to the measured value of 11.2% per decade. These results indicate that the proposed method may allow anomalous fading corrected IRSL dating beyond the linear part of the IRSL dose-response curve.
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.