Optically-Stimulated Luminescence is a late Quaternary dating technique used to date the last time quartz sediment was exposed to light. As sediment is transported by wind, water, or ice, it is exposed to sunlight and zeroed of any previous luminescence signal. Once this sediment is deposited and subsequently buried, it is removed from light and is exposed to low levels of natural radiation in the surrounding sediment. Through geologic time, quartz minerals accumulate a luminescence signal as ionizing radiation excites electrons within parent nuclei in the crystal lattice. A certain percent of the freed electrons become trapped in defects or holes in the crystal lattice of the quartz sand grain referred to as luminescent centers and accumulate over time Aitken, In our laboratory, these sediments are exposed to an external stimulus blue-green light and the trapped electrons are released. The released electrons emit a photon of light upon recombination at a similar site. In order to relate the luminescence given off by the sample to an age, we first need to obtain the dose equivalent to the burial dose.
The principles of Luminescence Dating
In luminescence dating, the signal accumulates within minerals over time as a function of low level, natural radiation exposure. The datable event is that point in time when the signal was reset to zero and started to grow again. The signal is essentially a dosimeter, converting to a chronometer by estimating the rate of dose absorption.
Optically stimulated luminescence (OSL) dating of fluvial sediments is widely younger than years, partial bleaching affects the accuracy of the results and.
With support from the National Science Foundation, the University of Washington luminescence dating laboratory headed by Dr. Because of its increased efficiency over the instrument the laboratory currently employs, the Riso machine will both increase throughput and decrease cost per sample. The Washington laboratory is the sole facility in the United States which routinely provides several types of luminescence analysis TL, OSL, IRSL for archaeological samples and the resultant dates have come to play an increasingly important function for archaeologists.
Because organic materials are present in only a limited number of sites many such occurrences are not amenable to radiocarbon dating and often luminescence provides the only alternative. Using a range of approaches it often possible to obtain dates from either ceramics or soil and in the former case luminescence has an advantage over radiocarbon since it can directly date the object of interest rather than associated material. Feathers has shown that luminescence may be as accurate as radiocarbon.
Traditional luminescence techniques analyze bulk samples comprised of many individual grains and the results can be problematic since particles of multiple ages and exposure histories may be present. Machines such as the Riso automated reader avoid this problem since they can date individual grains.
Optically Stimulated Luminescence
In most cases, the uncertainty will be higher, due to random errors e. Dating is possible for a wide age range of a few decades to about half a million years, although uncertainties are usually relatively large toward the extremes of this range. As with any method, results of luminescence dating contain errors or uncertainties. Adequate assessment of errors is important, for instance, to correctly assess rates of processes or leads and lags in natural or anthropogenic systems, or contemporaneity of different sites e.
The implication is that, for accurate dating of terrace formation, terrace sections straths using optically stimulated luminescence (OSL) dating techniques.
During the penultimate glaciation vast areas of the Alps were glaciated, with piedmont glaciers protruding into the foreland. In the easternmost part of the northward draining valleys of the Alps, the glaciers did not reach the foreland, but formed valley glaciers confined by the mountainous terrain. This also applies to the Ybbs valley, where samples for luminescence dating out of glaciofluvial gravel accumulations were taken at three locations along the present day river course.
In a highly dynamic depositional environment, such as a glacier-fed river system, incomplete resetting of the luminescence signal is possible, in particular when transport distances are short. Because previous research has shown, and as corroborated within this study, quartz from the research area exhibits analytical problems in the high age range. In combination with results from previous studies, we could reconstruct the valley evolution during the Riss glaciation.
Newly gained luminescence ages of the deglaciation in the easternmost Alps coincide with OSL dated deglaciation events in the Western Alps, indicating that climatic change along the north side of the Alps happened simultaneously. The Alpine region and its foreland played a major role in the investigation of Quaternary glacial and paleo-climatic processes since the beginning of the 19th century Agassiz, Based on three elevated, morphologically distinguishable gravel levels in the German NAF, the quadriglacial system was amended by three additional glacials Biber, Donau, Haslach by Eberl , Schaefer , and Schreiner and Haag This morphostratigraphic model is still used in some alpine areas, but has been fine-tuned and amended since then, especially in terms of the chronostratigraphic position of the deposits.
However, clear genetic relations in terms of the glacial series often can be ambiguous due to the complete lack of sedimentary remains and the often only poor preservation, especially those of the oldest glacials which underwent several cycles of severe geomorphological changes during subsequent glaciations and interglacials.
In this study we investigated the optically stimulated luminescence OSL and infrared stimulated luminescence IRSL properties of glaciofluvial quartz Q and potassium rich feldspar KFs deposited during the penultimate alpine glaciation along the eastern alpine Ybbs River Fig. For the first time luminescence ages from glaciofluvial sediments attributed to the penultimate glaciation from the eastern part of the alpine realm are presented.
1.4 Luminescence dating in archaeology
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The accuracy and precision of luminescence dating results are directly related to the type and quality of the material sampled and sample collection methods in.
The Luminescence Dating and Dosimetry Laboratory is developing new techniques for application to the dating of artefacts and deposits from sites that range widely in terms of chronological period, geographic location and material type. Recent work as focused on optically stimulated luminescence OSL techniques, in particular a novel experimental approach to the measurement of single grain OSL. A study produced, for the first time, absolute dates for a range of brick stupas located within the hinterland of Anuradhapura , contributing to the further development of a brick monument chronology for the region.
Ongoing work is examining whether unfired clay bricks from various sites can be dated accurately. OSL techniques are being applied to date sediment sequences in stratigraphic contexts associated with irrigation systems. In the absence of suitable organic samples for C dating, these systems are very difficult to date. New approaches are being applied to the dating of post-Roman irrigation systems in Spain to establish when they were created and used.
Also, as part of a major investigation supported by the European Research Centre and led by Prof. Sauer at the University of Edinburgh, a PhD project has started to investigate the application of OSL and geomorphological techniques to establish the chronology of irrigation systems and settlement sites associated with the demographic growth at the frontiers of the Sasanian Empire.
Optically stimulated luminescence and isothermal thermoluminescence dating of high sensitivity and well bleached quartz from Brazilian sediments: from Late Holocene to beyond the Quaternary? E-mail: andreos usp. E-mail: ligia. E-mail: ccfguedes gmail. E-mail: wsallu gmail. E-mail: assine rc.
This also applies to the Ybbs valley, where samples for luminescence dating out OSL, fading corrected K feldspar IR50 and pIRIR to identify reliable ages.
Luminescence Dating, Uncertainties, and Age Range
Over the last 60 years, luminescence dating has developed into a robust chronometer for applications in earth sciences and archaeology. The technique is particularly useful for dating materials ranging in age from a few decades to around ,—, years. In this chapter, following a brief outline of the historical development of the dating method, basic principles behind the technique are discussed. This is followed by a look at measurement equipment that is employed in determining age and its operation.
Optically stimulated luminescence (OSL) dating of quartz has been used accuracy of OSL technology, we think that the OSL data are reliable.
Introduction How do we measure the OSL signal? How do we measure the radiation dose rate? Another way of dating glacial landforms is optically stimulated luminescence dating OSL. OSL is used on glacial landforms that contain sand, such as sandur or sediments in glacial streams. The OSL signal is reset by exposure to sunlight, so the signal is reset to zero while the sand is being transported such as in a glacial meltwater stream. Once the sand grain has been buried and it is no longer exposed to sunlight, the OSL signal starts to accumulate.
OSL works because all sediments have some natural radioactivity, caused by the presence of uranium, thorium and potassium isotopes in heavy minerals such as zircons.
Luminescence dating laboratory
The possible role of environmental change, especially sea level change, as a stimulus for the development of human residence and migration is poorly understood. We investigate this problem by showing a record of sea-level change and coastal transformation based on a sediment core FN1 core and a Neolithic site Pingfengshan site obtained from the Funing bay on the northeast coast of Fujian, China.
Samples from FN1 core and Pingfengshan site were taken for grain size ananlyses and for optically stimulated luminescence OSL dating. The blue-light stimulated OSL signals were measured by the single aliquot regenerative dose SAR protocol to determine the ages of of the samples. The comparison of sea level change and Neolithic cultural periods presents a good relationship in coastal area of Fujian, China since about 7 ka before present.
In detail, the cultural types of Keqiutou culture and Huangguashan culture all belong to coastal mountainous culture, of which flourishing periods corresponds to the higher sea level periods of mid-late Holocene.
Abstract: Luminescence dating is a tool frequently used for age determination of Quaternary materials such as reliable and precise methods for determining.
Luminescence dating refers to a group of methods of determining how long ago mineral grains were last exposed to sunlight or sufficient heating. It is useful to geologists and archaeologists who want to know when such an event occurred. It uses various methods to stimulate and measure luminescence. All sediments and soils contain trace amounts of radioactive isotopes of elements such as potassium , uranium , thorium , and rubidium.
These slowly decay over time and the ionizing radiation they produce is absorbed by mineral grains in the sediments such as quartz and potassium feldspar. The radiation causes charge to remain within the grains in structurally unstable “electron traps”. The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried.
Stimulating these mineral grains using either light blue or green for OSL; infrared for IRSL or heat for TL causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral. Most luminescence dating methods rely on the assumption that the mineral grains were sufficiently “bleached” at the time of the event being dated.
Single Quartz OSL ages can be determined typically from to , years BP, and can be reliable when suitable methods are used and proper checks are done.
Luminescence Dating: Applications in Earth Sciences and Archaeology
Luminescence dating utilises energy deposited in mineral lattices by naturally occurring ionising radiation to record information encoding chronology, depositional process information, and thermal history records in ceramics, lithics, and sedimentary materials. Precision of dating varies from sample to sample, and from context to context, depending on individual sample characteristics mineralogy, luminescence sensitivity, stability and homogeneity of the radiation environment, and the quality of initial zeroing.
A well calibrated laboratory can produce accuracy at the lower end of the precision scale. For high quality work it is important that the environmental gamma dose rates are recorded in-situ at time of excavation, which is most readily facilitated by involving the dating laboratory in fieldwork. The key importance of luminescence dating within Scottish Archaeology lies in the nature of the events represented by the various dating materials.
In this respect, and in extending the range of dating materials and questions available, there have significant developments in recent years, and more can be anticipated.
Luminescence dating is a rapidly expanding field. Recent advances in methodology and instrumentation have improved both its accuracy and precision, such.
This paper aims to provide an overview concerning the optically stimulated luminescence OSL dating method and its applications for geomorphological research in France. An outline of the general physical principles of luminescence dating is given. A case study of fluvial sands from the lower terrace of the Moselle valley is then presented to describe the range of field and laboratory procedures required for successful luminescence dating.
The paper also reviews the place of OSL dating in geomorphological research in France and assesses its potential for further research, by focusing on the diversity of sedimentary environments and topics to which it can be usefully applied. Hence it underlines the increasing importance of the method to geomorphological research, especially by contributing to the development of quantitative geomorphology.
They are now largely used to date not only palaeontological or organic remains, but also minerals that characterise detrital clastic sedimentary material. The most common methods applied to minerals are cosmogenic radionuclides, electron spin resonance ESR and luminescence techniques. The latter were first applied to burned minerals from archaeological artefacts [thermoluminescence TL method].
Improvements of this technique led to the development, for more than twenty years, of the optical dating method [commonly referred to as Optically Stimuled Luminescence OSL ] which is now applied to sediments from various origins Wintle, The aim of this paper is to provide people involved in geomorphological research a global overview about the principles and procedures of optical dating, from the field sampling to the age interpretation. Most of the publications actually focus on one part of either the method e.
The general principles of the method are described first. The paper then explains how OSL dating is applied to obtain a depositional age, through the field and laboratory procedures employed. These procedures are described as clearly as possible in order to provide useful information for geomorphologists interested in the method, and illustrated by a case study that has involved luminescence dating of fluvial sands samples LUM and LUM from the lower alluvial terrace of the Moselle River M1 terrace as defined by S.
Luminescence dating is used to identify when a sample was last exposed to daylight or extreme heat by estimating the amount of ionising radiation absorbed since burial or firing. This equation very simply expresses the calculations necessary, but it is important to be aware of the factors influencing the two values used. Heterogeneous sediments and radioactive disequilibria will increase errors on Dr, while incomplete bleaching of the sample prior to burial, anomalous fading in feldspars, and the estimation of past sediment moisture content may all also add to increased errors.
The dating of sediments using the luminescence signal generated by optical stimulation OSL offers an independent dating tool, and is used most often on the commonly occurring minerals of quartz and feldspar and, as such, has proved particularly useful in situations devoid of the organic component used in radiocarbon dating. Quartz has been used for dating to at least ka, while the deeper traps of feldspar have produced dates as old as 1 ma.
Accuracy, precision & range. There is now a substantial body of independent evidence that has verified the accuracy of luminescence dating, and there exist a.
Jain Mayank, Murray A. Optically stimulated luminescence dating: how significant is incomplete light exposure in fluvial environments? In: Quaternaire , vol. Fluvial Archives Group. Clermond-Ferrant Optically stimulated luminescence OSL dating of fluvial sediments is widely used in the interpretation of fluvial response to various allogenic forcing mechanisms during the last glacial-mterglacial cycle.
We provide here a non-specialist review highlighting some key aspects of recent development in the OSL dating technique relevant to the Quaternary fluvial community, and describe studies on dating of fluvial sediments with independent chronological control, and on recent fluvial sediment. Quaternaire, 15, , , p Obtaining chronologies for fluvial deposits is an important component in understanding the fluvial response to changes in climate, sea-level, tectonic and anthropogenic factors.
Optically stimulated luminescence OSL dating is now widely used by Quaternary scientists; it can provide ages in a range well beyond that of radiocarbon and on deposits from environments not conducive to the preservation of organic matter.