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.
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.
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 techniquemeaning that the amount of energy emitted is a direct result of the event being measured. Better still, unlike radiocarbon datingthe effect luminescence dating measures increases with time.
Luminescence dating: A family of chronologic methods typically applied to the commonly occurring minerals quartz and feldspar, which exploits a time-dependent signal that builds up in mineral grains by exposure to naturally occurring ionizing radiation principally from uranium, thorium, and potassium. The methods assess the time elapsed since these mineral grains were last exposed to sunlight or to heating. In the case of marine and lacustrine sediments, the event being dated is the last exposure to sunlight, i. Deep-sea, marine: Of or pertaining to the deeper parts of the sea or ocean as opposed to shallow waters and coasts.
Luminescence dating typically refers to a suite of radiometric geologic dating techniques whereby the time elapsed since the last exposure of some silicate minerals to light or heat can be measured. When dosed minerals are then re-exposed to light or heat, they release the stored electrons, emitting a photon of light that is referred to as luminescence. This 'bleaching' process empties the electrons stored in the traps and resets or 'zeroes' the signal.
Jain Mayank, Murray A. Optically stimulated luminescence dating: how significant is incomplete light exposure in fluvial environments? In: Quaternairevol.
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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.
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.
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.