View source for Physics:Luminescence dating

{{short description|Form of dating how long ago mineral grains had been last exposed to sunlight or heating}}
'''Luminescence dating''' refers to a group of [[Physics:Chronological dating|chronological dating]] methods of determining how long ago [[Earth:Mineral|mineral]] grains were last exposed to sunlight or sufficient heating. It is useful to [[Geologist|geologist]]s and archaeologists who want to know when such an event occurred. It uses various methods to stimulate and measure [[Physics:Luminescence|luminescence]].

It includes techniques such as [[Physics:Optically stimulated luminescence|optically stimulated luminescence]] (OSL), infrared stimulated luminescence (IRSL), and [[Physics:Thermoluminescence dating|thermoluminescence dating]] (TL). "Optical dating" typically refers to OSL and IRSL, but not TL. The age range of luminescence dating methods extends from a few years<ref>Montret et al., 1992</ref> to over one million years.<ref>Fattahi M., Stokes S., 2001</ref>

==Conditions and accuracy==
All [[Earth:Sediment|sediment]]s and [[Chemistry:Soil|soil]]s contain trace amounts of [[Physics:Radioactive|radioactive]] [[Physics:Isotope|isotope]]s of elements such as [[Chemistry:Potassium|potassium]], [[Chemistry:Uranium|uranium]], [[Chemistry:Thorium|thorium]], and [[Chemistry:Rubidium|rubidium]]. These slowly [[Physics:Radioactive decay|decay]] over time and the [[Physics:Ionizing radiation|ionizing radiation]] they produce is absorbed by mineral grains in the sediments such as [[Chemistry:Quartz|quartz]] and [[Chemistry:Potassium feldspar|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; [[Physics:Infrared|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. For example,  in quartz a short daylight exposure in the range of 1–100 seconds before burial is sufficient to effectively “reset” the OSL dating clock.<ref name = "Rhodes 2011" /> This is usually, but not always, the case with [[Earth:Aeolian processes|aeolian]] deposits, such as sand dunes and [[Earth:Loess|loess]], and some water-laid deposits.
Single 
Quartz OSL ages can be determined typically from 100 to 350,000 years BP, and can be reliable when suitable methods are used and proper checks are done.<ref>{{Cite journal|author1=Murray, A. S.  |author2=Olley, J. M.  |name-list-style=amp |title=Precision and accuracy in the optically stimulated luminescence dating of sedimentary quartz: a status review |journal=Geochronometria|volume=21|year=2002|pages=1–16|url=http://www.geochronometria.pl/pdf/geo_21/geo21_01.pdf |access-date=February 8, 2016 }}</ref> Feldspar IRSL techniques have the potential to extend the datable range out to a million years as feldspars typically have significantly higher dose saturation levels than quartz, though issues regarding anomalous fading will need to be dealt with first.<ref name = "Rhodes 2011">{{Cite journal|author= Rhodes, E. J. |title=Optically stimulated luminescence dating of sediments over the past 250,000 years |journal=Annual Review of Earth and Planetary Sciences|volume=39|year=2011|pages=461–488| doi=10.1146/annurev-earth-040610-133425|bibcode=2011AREPS..39..461R }}</ref> Ages can be obtained outside these ranges, but they should be regarded with caution. The uncertainty of an OSL date is typically 5-10% of the age of the sample.<ref name = "Roberts 2015">{{Cite journal|author= Roberts, R.G., Jacobs, Z., Li, B., Jankowski, N.R., Cunningham, A.C., & Rosenfeld, A.B. |title=Optical dating in archaeology: thirty years in retrospect and grand challenges for the future |journal=Journal of Archaeological Science|volume=56|year=2015|pages=41–60 | doi=10.1016/j.jas.2015.02.028|url=https://ro.uow.edu.au/cgi/viewcontent.cgi?article=3831&context=smhpapers }}</ref>

There are two different methods of OSL dating: multiple-aliquot-dose and single-aliquot-regenerative-dose (SAR). In multiple-aliquot testing, a number of grains of sand are stimulated at the same time and the resulting luminescence signature is averaged.<ref name=":0">{{Cite journal|last=Jacobs, Z and Roberts, R|date=2007|title=Advances in Optically Stimulated Luminescence Dating of Individual Grains of Quartz from Archaeological Deposits|journal=Evolutionary Anthropology|volume=16|issue=6|pages=218|doi=10.1002/evan.20150|s2cid=84231863}}</ref> The problem with this technique is that the operator does not know the individual figures that are being averaged, and so if there are partially prebleached grains in the sample it can give an exaggerated age.<ref name=":0" /> In contrast to the multiple-aliquot method, the SAR method tests the burial ages of individual grains of sand which are then plotted. Mixed deposits can be identified and taken into consideration when determining the age.<ref name=":0" />

==History==
The concept of using luminescence dating in archaeological contexts was first suggested in 1953 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.<ref>{{Cite journal|author= Daniels, F., Boyd, C.A., & Saunders, D.F. |title=Thermoluminescence as a research tool |journal=Science|volume=117|issue = 3040|year=1953|pages=343–349|doi=10.1126/science.117.3040.343|pmid=17756578 |bibcode=1953Sci...117..343D }}</ref> Experimental tests on archaeological ceramics followed a few years later in 1960 by Grögler et al.<ref>{{Cite journal|author= Grögler, N., Houtermans, F.G., & Stauffer, H. |title= Über die datierung von keramik und ziegel durch thermolumineszenz. |journal= Helvetica Physica Acta|volume=33|year=1960|pages=595–596 |url= http://retro.seals.ch/digbib/view2?pid=hpa-001:1960:33::601 | access-date=February 16, 2016 }}</ref> Over the next few decades, thermoluminescence research was focused on heated pottery and ceramics, burnt flints, baked hearth sediments, oven stones from burnt mounds and other heated objects.<ref name = "Roberts 2015" />

In 1963, Aitken et al. noted that TL traps in calcite could be bleached by sunlight as well as heat,<ref name = "Aitken 1963">{{Cite journal|author= Aitken, M.J., Tite, M.S. & Reid, J. |title=Thermoluminescent dating: progress report |journal=Archaeometry|volume=6|year=1963|pages=65–75 | doi=10.1111/j.1475-4754.1963.tb00581.x}}</ref> and in 1965 Shelkoplyas and Morozov were the first to use TL to date unheated sediments.<ref>{{Cite journal|author1=Shelkoplyas, V.N.  |author2=Morozov, G.V.  |name-list-style=amp |title=Some results of an investigation of Quaternary deposits by the thermoluminescence method |journal=Materials on the Quaternary Period of the Ukraine|volume=7th International Quaternary Association Congress, Kiev|year=1965|pages=83–90 }}</ref> Throughout the 70s and early 80s TL dating of light-sensitive traps in geological sediments of both terrestrial and marine origin became more widespread.<ref>{{Cite journal|author1=Wintle, A.G.  |author2=Huntley, D.J.  |name-list-style=amp |title=Thermoluminescence dating of sediments |journal=Quaternary Science Reviews|volume=1|year=1982|issue=1 |pages=31–53| doi= 10.1016/0277-3791(82)90018-X |bibcode=1982QSRv....1...31W }}</ref>

Optical dating using optically stimulated luminescence (OSL) was developed in 1984 by David J. Huntley and colleagues.<ref>{{Cite journal|author=Huntley, D. J., Godfrey-Smith, D. I., & Thewalt, M. L. W. |title=Optical dating of sediments |journal=Nature|volume=313|issue=5998 |year=1985| pages=105–107 |doi=10.1038/313105a0|bibcode=1985Natur.313..105H |s2cid=4258671 }}</ref> Hütt et al. laid the groundwork for the infrared stimulated luminescence (IRSL) dating of potassium feldspars in 1988.<ref>{{Cite journal|author= Hütt, G., Jaek, I. & Tchonka, J. |title= Optical dating: K-feldspars optical response stimulation spectra |journal=Quaternary Science Reviews|volume=7|issue= 3–4 |year=1988| pages=381–385 |doi=10.1016/0277-3791(88)90033-9 |bibcode= 1988QSRv....7..381H }}</ref> The traditional OSL method relies on optical stimulation and transfer of electrons from one trap, to holes located elsewhere in the lattice – necessarily requiring two defects to be in nearby proximity, and hence it is a destructive technique. The problem is that nearby electron/hole trapping centres suffer from localized tunneling, eradicating their signal over time; it is this issue that currently defines the upper age-limit for OSL dating

In 1994, the principles behind optical and [[Physics:Thermoluminescence dating|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.<ref name=":1">{{Cite journal|author=Liritzis, I.|title=Surface Dating by Luminescence: An Overview|journal=Geochronometria|volume=38 | issue = 3|year=2011|pages=292–302|doi=10.2478/s13386-011-0032-7|doi-access=free}}</ref><ref>{{Cite journal|author=Liritzis, I., Polymeris, S.G., and Zacharias, N.|title=Surface Luminescence Dating of 'Dragon Houses' and Armena Gate at Styra (Euboea, Greece)|journal=Mediterranean Archaeology and Archaeometry|volume=10 | issue = 3|year=2010|pages=65–81|bibcode=2010MAA....10...65L}}</ref><ref>{{Cite journal|author=Liritzis, I.|title=Strofilas (Andros Island, Greece): new evidence for the cycladic final neolithic period through novel dating methods using luminescence and obsidian hydration|journal=Journal of Archaeological Science|volume=37|issue=6|year=2010|pages=1367–1377|doi=10.1016/j.jas.2009.12.041}}</ref>

==Physics==
Luminescence dating is one of several techniques in which an age is calculated as follows:
<blockquote>age = (total absorbed radiation dose) / (radiation dose rate) <ref name=":1" /></blockquote>
The radiation dose rate is calculated from measurements of the [[Physics:Radioactive|radioactive]] elements (K, U, Th and Rb) within the sample and its surroundings and the radiation dose rate from [[Astronomy:Cosmic ray|cosmic ray]]s. The dose rate is usually in the range 0.5 - 5 [[Physics:Gray (unit)|grays]]/1000 years. The total absorbed radiation dose is determined by exciting, with light, specific minerals (usually [[Chemistry:Quartz|quartz]] or [[Chemistry:Potassium feldspar|potassium feldspar]]) extracted from the sample, and measuring the amount of light emitted as a result. The [[Physics:Photon|photon]]s of the emitted light must have higher energies than the excitation photons in order to avoid measurement of ordinary [[Physics:Photoluminescence|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.

==Minerals==
The minerals that are measured are usually either quartz or potassium feldspar sand-sized grains, or unseparated silt-sized grains. There are advantages and disadvantages to using each. For quartz, blue or green excitation frequencies are normally used and the near ultra-violet emission is measured. For potassium feldspar or silt-sized grains, near infrared excitation (IRSL) is normally used and violet emissions are measured.

==Comparison to radiocarbon dating==
Unlike [[Physics:Radiocarbon dating|carbon-14 dating]], luminescence dating methods do not require a contemporary organic component of the sediment to be dated; just quartz, potassium feldspar, or certain other mineral grains that have been fully bleached during the event being dated. These methods also do not suffer from overestimation of dates when the sediment in question has been mixed with “old carbon”, or {{chem|14|C}}-deficient carbon that is not the same isotopic ratio as the atmosphere. In a study of the chronology of arid-zone [[Earth:Lake|lacustrine]] sediments from Lake Ulaan in southern Mongolia, Lee et al. discovered that OSL and radiocarbon dates agreed in some samples, but the radiocarbon dates were up to 5800 years older in others.<ref name = "Lee 2011">{{Cite journal|author= Lee, M.K., Lee, Y.I., Lim, H.S., Lee, J.I., Choi, J.H., & Yoon, H.I. |title=Comparison of radiocarbon and OSL dating methods for a Late Quaternary sediment core from Lake Ulaan, Mongolia|journal=Journal of Paleolimnology |volume=45|issue=2|year=2011|pages=127–135| doi=10.1007/s10933-010-9484-7 |bibcode=2011JPall..45..127L|s2cid=128511753}}</ref>

The sediments with disagreeing ages were determined to be deposited by aeolian processes.  Westerly winds delivered an influx of {{chem|14|C}}-deficient carbon from adjacent soils and [[Earth:Paleozoic|Paleozoic]] carbonate rocks, a process that is also active today. This reworked carbon changed the measured isotopic ratios, giving a false older age. However, the wind-blown origin of these sediments were ideal for OSL dating, as most of the grains would have been completely bleached by sunlight exposure during transport and burial. Lee et al. concluded that when aeolian sediment transport is suspected, especially in lakes of arid environments, the OSL dating method is superior to the radiocarbon dating method, as it eliminates a common ‘old-carbon’ error problem.<ref name = "Lee 2011" />

== Other uses ==
One of the benefits of luminescence dating is that it can be used to confirm the authenticity of an artifact. Under proper low light conditions a sample in the tens of milligrams can be used.<ref>{{Citation|last1=Liritzis|first1=Ioannis|title=Luminescence-Based Authenticity Testing|date=2013|work=Luminescence Dating in Archaeology, Anthropology, and Geoarchaeology: An Overview|pages=41–43|editor-last=Liritzis|editor-first=Ioannis|series=SpringerBriefs in Earth System Sciences|place=Heidelberg|publisher=Springer International Publishing|language=en|doi=10.1007/978-3-319-00170-8_5|isbn=978-3-319-00170-8|last2=Singhvi|first2=Ashok Kumar|last3=Feathers|first3=James K.|last4=Wagner|first4=Gunther A.|last5=Kadereit|first5=Annette|last6=Zacharias|first6=Nikolaos|last7=Li|first7=Sheng-Hua|editor2-last=Singhvi|editor2-first=Ashok Kumar|editor3-last=Feathers|editor3-first=James K.|editor4-last=Wagner|editor4-first=Gunther A.}}</ref>

== See also ==
* [[Physics:Radiometric dating|Radiometric dating]]

==Notes==
<references/>

==References==
* Aitken, M. J. (1998). ''An introduction to optical dating: the dating of Quaternary sediments by the use of photon-stimulated luminescence''. Oxford University Press. {{ISBN|0-19-854092-2}}
* {{cite journal | author = Greilich S., Glasmacher U. A., Wagner G. A. | year = 2005 | title = Optical dating of granitic stone surfaces | journal = Archaeometry | volume = 47 | issue = 3| pages = 645–665 | doi = 10.1111/j.1475-4754.2005.00224.x }}
* {{cite journal | author = Habermann J., Schilles T., Kalchgruber R., Wagner G. A. | year = 2000 | title = Steps towards surface dating using luminescence | journal = Radiation Measurements | volume = 32 | issue = 5| pages = 847–851 | doi = 10.1016/s1350-4487(00)00066-4 | bibcode = 2000RadM...32..847H }}
* {{cite journal | author = Liritzis I | year = 1994 | title = A new dating method by thermoluminescence of carved megalithic stone building | journal = Comptes Rendus de l'Académie des Sciences, Série II | volume = 319 | issue = 5| pages = 603–610 }}
* {{cite journal | author = Liritzis I., Guibert P., Foti F., Schvoerer M. | year = 1997 | title = The temple of Apollo (Delphi) strengthens novel thermoluminescence dating method | journal = Geoarchaeology | volume = 12 | issue = 5| pages = 479–496 | doi = 10.1002/(sici)1520-6548(199708)12:5<479::aid-gea3>3.0.co;2-x }}
* {{cite journal | author = Liritzis I | year = 2010 | title = Strofilas (Andros Island, Greece): New evidence of Cycladic Final Neolithic dated by novel luminescence and Obsidian Hydration methods | journal = Journal of Archaeological Science | volume = 37 | pages = 1367–1377 | doi = 10.1016/j.jas.2009.12.041 }}
* {{cite journal | author = Liritzis I., Sideris C., Vafiadou A., Mitsis J. | year = 2008 | title = Mineralogical, petrological and radioactivity aspects of some building material from Egyptian Old Kingdom monuments | journal = Journal of Cultural Heritage | volume = 9 | issue = 1| pages = 1–13 | doi = 10.1016/j.culher.2007.03.009 }}
* {{cite journal | author = Morgenstein M. E., Luo S., Ku T. L., Feathers J. | year = 2003 | title = Uranium-series and luminescence dating of volcanic lithic artefacts | journal = Archaeometry | volume = 45 | issue = 3| pages = 503–518 | doi = 10.1111/1475-4754.00124 }}
* {{cite journal | author = Rhodes E. J. | year = 2011 | title = Optically stimulated luminescence dating of sediments over the past 200,000 years | journal = Annual Review of Earth and Planetary Sciences | volume = 39 | pages = 461–488 | doi = 10.1146/annurev-earth-040610-133425 | bibcode = 2011AREPS..39..461R }}
* {{cite journal | author = Roberts R. G., Jacobs Z., Li B., Jankowski N. R., Cunningham A. C., Rosenfeld A. B. | year = 2015 | title = Optical dating in archaeology: thirty years in retrospect and grand challenges for the future | url = https://ro.uow.edu.au/cgi/viewcontent.cgi?article=3831&context=smhpapers| journal = Journal of Archaeological Science | volume = 56 | pages = 41–60 | doi = 10.1016/j.jas.2015.02.028 }}
* {{cite journal | author = Theocaris P. S., Liritzis I., Galloway R. B. | year = 1997 | title = Dating of two Hellenic pyramids by a novel application of thermoluminescence | journal = Journal of Archaeological Science | volume = 24 | issue = 5| pages = 399–405 | doi = 10.1006/jasc.1996.0124 }}
* {{cite journal | author = Wintle A. G., Murray A. S. | year = 2006 | title = A review of quartz optically stimulated luminescence characteristics and their relevance in single-aliquot regeneration dating protocols | journal =  Radiation Measurements | volume = 41 | issue = 4 |pages=369–391 | doi = 10.1016/j.radmeas.2005.11.001 | bibcode = 2006RadM...41..369W }}
* {{cite journal | author = Montret, M., Fain, J., Miallier, D. | title = TL dating in the Holocene using red TL from quartz| year = 1992 | journal = Ancient TL 10| volume = 10 | issue = | pages = 33–36 |url=http://ancienttl.org/ATL_10-3_1992/ATL_10-3_Montret_p33-36.pdf }}
* {{cite journal | author =Fattahi M., Stokes S.| year = 2001 | title = Extending the time range of luminescence dating using red TL (RTL) from volcanic quartz.  | journal = Radiation Measurements | volume = 32 | issue = 5–6| pages = 479–485 | doi = 10.1016/S1350-4487(00)00105-0 }}
{{Chronology}}

{{DEFAULTSORT:Luminescence Dating}}
[[Category:Geochronological dating methods]]
[[Category:Light]]

{{Sourceattribution|Luminescence dating}}