Luminescence and ESR Dating
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. Here the application of quartz OSL to the dating of rock surfaces is successfully tested by application to two different quartz-rich rock types sandstone and quartzite. Together with the measurement of infrared stimulated luminescence IRSL signals as a function of depth into the surface of different granites it is clear that both OSL and IRSL can be fully reset in the two mm closest to the rock surface. However, it appears that the sensitivity of quartz from the granitic rocks the most common surficial rock type cannot be relied on.
The OSL Lab
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.
We provide here a non-specialist review highlighting some key aspects of recent development in the OSL dating technique relevant to the Quaternary fluvial.
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. The use of fine-grain dating for samples such as pottery, loess, burnt flint and lacustrine sediments, and coarse-grain dating of aeolian, fluvial and glacial sediments is regularly undertaken.
While thermoluminescence TL, the generation of a luminescence signal generated by thermal stimulation is still conducted on pottery and burnt flint samples, the bulk of luminescence dating now uses optical stimulation as this releases a signal that is far more readily zeroed than that re-set by heat. Analysis of fully bleached samples is preferred as this ensures that associated errors are kept to a minimum.
School of Geography and the Environment, University of Oxford
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.
This paper discusses the details of recent advances in the method and several examples of its application to material from archaeological excavations of Medieval to Palaeolithic sites. Skip to main content Skip to sections.
Abstract: Luminescence dating is a tool frequently used for age determination of Quaternary materials such as archaeological artefacts, volcanic deposits and a.
In physics , optically stimulated luminescence OSL is a method for measuring doses from ionizing radiation. It is used in at least two applications:. The method makes use of electrons trapped between the valence and conduction bands in the crystalline structure of certain minerals most commonly quartz and feldspar. The ionizing radiation produces electron-hole pairs: Electrons are in the conduction band and holes in the valence band. The electrons that have been excited to the conduction band may become entrapped in the electron or hole traps.
Under the stimulation of light, the electrons may free themselves from the trap and get into the conduction band. From the conduction band, they may recombine with holes trapped in hole traps. If the centre with the hole is a luminescence center radiative recombination centre , emission of light will occur. The photons are detected using a photomultiplier tube.
Optically Stimulated Luminescence (OSL) Dating in the Amazonian Wetlands
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.
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. When a laser light source is used to stimulate the release of electrons, the process is called optically stimulated luminescence.
Optically stimulated luminescence OSL dating has proven to be extremely useful for establishing the Late Quaternary chronological framework in many areas of the Brazilian territory. In this region dominated by tropical climate, OSL dating can be more extensively applied than radiocarbon dating due to the generally low potential for the preservation of organic matter in sedimentary samples. This problem is especially critical in areas of the Amazonian lowlands, because of the hot climate and high precipitation rates.
With the assistance of Fugro LABORATORY we have developed a method for Luminescence dating is a technique used to date Quaternary sediments and for.
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. The availability of chronologies for aeolian horizons obtained using OSL provides a valuable tool in the study of the evolution of coastal landscape and how past coastal communities responded to climate change.
The OSL dating of sands and palaeosol horizons, supported by geomorphological analysis, has identified critical stages in the development of the landscape on Herm on which megalithic monuments were constructed during the Neolithic period. The OSL dates identified three phases of significant aeolian activity during the prehistoric period, the onset dated to ca , and years ago and evidence of ploughing activity was placed in the late 2nd millennium BC and in the 4th and 13th centuries AD.
The testing of sediments directly associated with structures and monuments on Herm continues.
This work is licensed under a Creative Commons Attribution 4. Dating agricultural terraces is a notoriously difficult problem for archaeologists. The frequent occurrence of residual material in terrace soils and the potential for post-depositional disturbance mean that conventional artefactual and lab-based dating methods often provide unreliable dates.
Luminescence dating is a chronological method that has been used extensively in archaeology and the earth sciences. It is based on the emission of light.
Chronology is a crucial scientific question for both archaeologic and paleoenvironmental studies on the Qinghai-Tibetan Plateau QTP. In the QB, very few early archaeological sites were found, because of the erosional environment, which is not suitable for the preservation of human activity remains HARs. As a result, artifacts were usually found on the ground surface, e. Methodologically, both OSL dating and 14 C dating should be suitable for archaeological sites in aeolian sediments.
Hou et al. Sun et al. These studies showed agreement between OSL and 14 C dating and offered reliable chronologies for these sites; however, more disagreements were found with the increasing amount of ages. Download Figure Download figure as PowerPoint slide Geomorphology of the study region and location of the sections.
The yellow dots with red centers show the archaeological sites mentioned in this studies, e. The red dots with white centers display the towns and sections in this region, respectively. Citation: Geochronometria 43, 1; In the Yutian site Fig. Finally the age of this site were proposed to be ca. In the eastern QB, Niu et al.