James K. Feathers, Vance T. Holliday , David J. The Southern High Plains of North America is rich in archaeological sites, but many are not well constrained chronologically, owing to a lack of material for radiocarbon dating. A program of optically stimulated luminescence OSL dating, applying mainly single-grain analyses, was therefore initiated. Many samples have independent age estimates from radiocarbon to check the OSL results, but OSL age estimates are also provided for those sites that otherwise lack secure chronological control.
Luminescence Dating: Applications in Earth Sciences and Archaeology
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.
A program of optically stimulated luminescence (OSL) dating, applying mainly single-grain analyses, was therefore initiated. Many samples have independent.
Optically stimulated luminescence dating at Rose Cottage Cave. A single-grain analysis demonstrates that the testing procedure for feldspar fails to reject single aliquots containing feldspar and the overestimate of age is attributed to this. Seven additional luminescence dates for the Middle Stone Age layers combined with the 14 C chronology establish the terminal Middle Stone Age deposits at 27 years ago, while stone tool assemblages that are transitional between the Middle Stone Age and the Late Stone Age are dated to between 27 years and 20 years ago.
Although there are inconsistencies in the Middle Stone Age dates, the results suggest that the Howiesons Poort at Rose Cottage Cave dates to between 70 years and 60 years ago. Much of the rich archaeological heritage in southern Africa is older than 50 years, which is the limit of the ubiquitous 14 C dating technique. In order to make appropriate inter-site comparisons of artefactual evidence, and further to compare the trajectory of human adaptation with external factors such as changing climates, it is necessary to establish a reliable chronological framework.
Optically stimulated luminescence OSL dating has become one of the foremost techniques in establishing this framework. OSL is based on the build-up and release of radiation energy in crystalline minerals, typically quartz. The charge build-up manifests as electrons, mobilized in the quartz matrix by environmental radiation, which populate pre-existing energy minima that are called ‘traps’. OSL dates represent the time since electron traps within the quartz grains were previously emptied or bleached by heating or exposure to sunlight.
The equivalent dose D e of the sample is divided by the dose rate to calculate the age. Luminescence techniques applied to quartz can be used to obtain depositional ages up to years in certain environments. Several criteria need to be met in order to achieve accurate OSL results.
Optically Stimulated Luminescence (OSL) Dating
Resources home v2. Introduction Services Prices. Application Central for samples up to about Lund containing quartz. Technical Geography Laboratory All sediments contain trace minerals including uranium, thorium and potassium.
This paper aims to provide an overview concerning the optically stimulated luminescence (OSL) dating method and its applications for geomorphological.
Please reference: Mallinson, D. Optically stimulated luminescence is a method of determining the age of burial of quartz or feldspar bearing sediments based upon principles of radiation and excitation within crystal lattices, and stems from the fact that imperfections in a crystal lattice have the ability to store ionizing energy Aitken , ; Botter -Jensen et al. Radiation within sediments comes from alpha, beta, and gamma radiation emitted during the decay of U, U, Th, 40 K, and 87 Rb, and their daughter products, both within the mineral grains and in their surroundings Lian , , and from cosmic rays Figure 1.
Under controlled laboratory conditions, assuming the sample was collected under light-restricted conditions, controlled exposure of the sample to photons yields a luminescence response the equivalent dose, D e , the intensity of which is a function of the dose rate within the sediment, and the length of time the sample was exposed to the background radiation.
In order to measure the age, two factors must be known; 1 the environmental dose rate, and 2 the laboratory dose of radiation that produces the same intensity of luminescence as did the environmental radiation dose the equivalent dose. Dividing the equivalent dose by the dose rate yields time. Samples for OSL analysis are typically collected from opaque core tubes aluminum or black pvc tubes that are pushed into the sediment using coring equipment vibracore , geoprobe , etc.
Samples are then extracted for processing under dark-room conditions. This is followed by sieving, heavy liquid Li- or Na- polytungstate separation, and sometimes magnetic separation to concentrate quartz sands of the appropriate size.
Optically stimulated luminescence
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. Luminescence properties of minerals used in dating are then examined after which procedures used in age calculation are looked at.
The first successful application of Optically Stimulated Luminescence While exploration of Australian post-colonial (≤ ka) OSL dating is.
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. The development of optically stimulated luminescence OSL dating of sediments has led to considerable advance in the geochronology of the Quaternary.
OSL dating is a well established technique to determine sediment burial ages from tens of years to few hundred thousand years. Recent studies have shown that Quaternary sediments of Brazil are dominated by quartz grains with high luminescence sensitivity, allowing the determination of precise and reliable OSL burial ages. We discuss the OSL data and ages of sediments from carbonate and terrigenous distributary and tributary systems fluvial depositional contexts in Brazil.
Optically Stimulated Luminescence dating
Portable Spectrofluorimeter for non-invasive analysis of cultural heritage artworks using LED sources. Luminescence spectroscopy – Spatially resolved luminescence – Time resolved luminescence – Electron spin resonance ESR. Flint and heated rocks – Ceramics and pottery – Unheated rock surfaces – Tooth enamel and quartz grains – Sediment dating. LexEva is a newly released evaluation software developed for analysis in luminescence research and dating.
Few years depending on signal intensity and sensitivity of equipment for which the lexsyg systems are especially developed.
OSL is an acronym for Optically-Stimulated Luminescence. Optically-Stimulated Luminescence is a late Quaternary dating technique used to date the last time.
Luminescence dating including thermoluminescence and optically stimulated luminescence is a type of dating methodology that measures the amount of light emitted from energy stored in certain rock types and derived soils to obtain an absolute date for a specific event that occurred in the past. The method is a direct dating technique , meaning that the amount of energy emitted is a direct result of the event being measured. Better still, unlike radiocarbon dating , the effect luminescence dating measures increases with time.
As a result, there is no upper date limit set by the sensitivity of the method itself, although other factors may limit the method’s feasibility. To put it simply, certain minerals quartz, feldspar, and calcite , store energy from the sun at a known rate. This energy is lodged in the imperfect lattices of the mineral’s crystals.
OSL Dating in Archaeology
Joel Q. Optically stimulated luminescence dating of young sediments and dusts. N2 – In many geological and archaeological studies investigated within a Late Quaternary timeframe, one or more of a suite of different optically stimulated luminescence OSL approaches may now be applied to provide critical chronological constraint. Such luminescence applications might be in instances where age exceeds radiocarbon limits or there is a paucity of organic material. Accurate luminescence geochronology of very young 10s to s yr timeframe deposits is also achievable, provided that certain luminescence characteristics and depositional environment factors hold true.
Important considerations are: sufficiently high specific luminescence sensitivity to enable measurement of very small doses; whether thermal transfer signals lead to dose overestimation; a more familiar problem of extent of optical resetting; and, whether the dose-rate is accurately reconstructed for shallow-depth surficial deposits with changing depositional environment.
The basic premise of mortar dating by optically stimulated luminescence (OSL) is that quartz in the sand used for making mortar has been.
The OSL optically stimulated luminescence dating method exploits dosimetric properties of grains of minerals naturally occurring in sediments and man-made materials. In archaeology the OSL method is used to date pottery and other heated materials e. When compared with the radiocarbon method it makes possible dating objects containing no organic matter or originating in periods for which the radiocarbon method is less accurate due to the shape or lack of the calibration curve.
Luminescence Dating Laboratory
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.
Other terms used to describe OSL include optical dating  and photon-stimulated luminescence dating or photoluminescence dating .
Put simply, OSL dating techniques gives us an estimate of the time since mineral grains were last exposed to sunlight. Professor Jacobs used her OSL dating technique to analyse 28, individual grains of quartz from Madjebebe , which revealed groundbreaking information about the arrival of the first modern humans in Australia.
Little grains moving around in the landscape are like little batteries. Sand gets buried in the archeological site and builds up energy. Scientists go into the site and take the sample in the dark, because of course if the samples are exposed to light, the signal is reset. Samples are taken back to the lab and carefully handled in darkroom conditions.
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.
Up to now not a single dating technique has been developed for in-situ planetary exploration. The only information on the age of extraterrestrial planetary surfaces comes from the “crater-counting” method. This method has an inherent large error and low resolution and is completely inadequate for local geology. Luminescence dating has possibly the potential to open up a completely new discipline in planetary in-situ exploration.
This assessment has a strategic value for the development of a new generation of in-situ instrumentation. Sedimentation processes on Mars are completely unexplored. In addition, fluid phases may have contributed significantly to erosion and transport processes to form the Martian landscape. Dating of buried grains in sedimentary layers would give a crucial contribution to the understanding of surface forming processes and is essential for any further exploration of planet Mars.
It is therefore essential to develop a method, which can determine the chronology of sedimentary deposits. Such a technique must be incorporated into an instrument requiring low resources mass, power, volume and placed onto the surface of Mars. Since various sites on the Martian surface need to be visited, the instrument must be incorporated into a mobile surface rover having a soil penetration capability or a sample retrieval system.
The OSL method has been demonstrated its suitability in portable instruments during the fieldwork in sedimentary deposits on Earth. The Martian environment however differs considerably concerning environmental conditions and mineralogical composition of sedimentary deposits from Earth. A careful assessment of these aspects and the best suitable OSL technique itself is required prior a breadboard design.
Optically stimulated Luminescence dating of quartz
Optically stimulated luminescence dating of rock surfaces. N2 – There are many examples of rock surfaces, rock art and stone structures whose ages are of great importance to the understanding of various phenomena in geology, climatology and archaeology. Optically stimulated luminescence OSL dating is a well-established chronological tool that has successfully determined the depositional age of a wide variety of fine-grained sediments, from several years to several hundred thousands of years.
However, there is no routine OSL dating method applicable to larger clasts such as cobbles, boulders and other rock surfaces.
Principles of Luminescence Dating. Optically stimulated luminescence was developed.
Scientists in North America first developed thermoluminescence dating of rock minerals in the s and s, and the University of Oxford, England first developed the thermoluminescence dating of fired ceramics in the s and s. During the s and s scientists at Simon Frasier University, Canada, developed standard thermoluminescence dating procedures used to date sediments.
In , they also developed optically stimulated luminescence dating techniques, which use laser light, to date sediments. The microscopic structure of some minerals and ceramics trap nuclear radioactive energy. This energy is in constant motion within the minerals or sherds. Most of the energy escapes as heat, but sometimes this energy separates electrons from the molecules that make up the minerals or ceramics. Usually the electrons will reconnect with the molecules, but some will not. The electrons that dont reconnect eventually encounter imperfections in the microscopic structure of the ceramics or minerals, and they become trapped by these imperfections.
Over time energy in the form of more and more trapped electrons is stored in these structural imperfections. By heating the ceramic or mineral to above degrees Celcius, these trapped electrons are released, creating a flash of light called thermoluminescence.