OSL specialists overcome these challenges through only sampling certain glacial landforms, where greater sunlight exposure is likely to have occurred prior to deposition e. A second challenge for OSL dating in glacial environments is that the luminescence sensitivity brightness of the quartz is often very low. Recent advances in OSL dating techniques for feldspar 2 , 3 may result in this becoming the preferred mineral for OSL dating of glacial sediments, although feldspars are often more severely affected by partial bleaching than quartz.
OSL has been widely used to date glacial sediments, because organic material required for radiocarbon dating is often absent. In Prep have sampled a suite of modern glaciofluvial sediments from Jostedalen, Southern Norway, to quantify the unbleached residuals of different glacial sediments and also to explore whether the luminescence signature of quartz and feldspars provides information about the different depositional pathways that sediments are transported along.
OSL dating can also be used effectively with other dating techniques such as cosmogenic nuclide dating. Quaternary Geochronology 5 , — Laboratory fading rates of various luminescence signals from feldspar-rich sediment extracts. Radiation Measurements 43 , A robust feldspar luminescence dating method for Middle and Late Pleistocene sediments.
Boreas 41 , Depositional pathway tracing in glacial catchments using the OSL of coarse-grained quartz and K-feldspar. Quaternary Science Reviews In Prep. Optically stimulated luminescence dating of glaciofluvial sediments on the Canterbury Plains, South Island, New Zealand.
Quaternary Geochronology 8 , Journal of Quaternary Science 24 , Quaternary Research, 65 1: Quaternary glaciation of Mount Everest. Quaternary Science Reviews, 28 This site uses Akismet to reduce spam. Learn how your comment data is processed. Photographs taken by Geoff Duller Aberystwyth University. 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.
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.
The concept of using luminescence dating in archaeological contexts was first suggested in by Farrington Daniels, Charles A. Boyd, and Donald F. Saunders, who thought the thermoluminescence response of pottery shards could date the last incidence of heating.
In , Aitken et al. In , the principles behind optical and thermoluminescence dating were extended to include surfaces made of granite, basalt and sandstone, such as carved rock from ancient monuments and artifacts. Ioannis Liritzis , the initiator of ancient buildings luminescence dating, has shown this in several cases of various monuments. The radiation dose rate is calculated from measurements of the radioactive elements K, U, Th and Rb within the sample and its surroundings and the radiation dose rate from cosmic rays.
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. Luminescence dating is a scientific method which dates certain artifacts by measuring the amount of light energy they have trapped.
The dose rate is usually in the range 0. The total absorbed radiation dose is determined by exciting, with light, specific minerals usually quartz or potassium feldspar extracted from the sample, and measuring the amount of light emitted as a result. The photons of the emitted light must have higher energies than the excitation photons in order to avoid measurement of ordinary photoluminescence.
A sample in which the mineral grains have all been exposed to sufficient daylight seconds for quartz; hundreds of seconds for potassium feldspar can be said to be of zero age; when excited it will not emit any such photons. The older the sample is, the more light it emits, up to a saturation limit.
This method is applicable to samples that range in age from a few hundred years to several hundred thousand years. The Limitations of Luminescence Dating Using this technique, almost any rock mineral or ceramic sample can be directly dated. However, it works best when dating heated grains in ceramics, obsidian, burned flint, and burned sediments.
Aberystwyth Luminescence Dating Laboratory. Center for Applied Dosimetry. Archaeometry Research Group Heidelberg, Germany.
A Review for Non-Specialists. Huntley, and Glenn W.
Canadian Journal of Earth Sciences Potassium Argon Dating Obsidian Hydration Dating