Radiokoolstofdatering, of koolstof 14-datering, word algemeen deur veral argeoloë gebruik om die ouderdom van voorwerpe te bepaal wat jonger as 50 000 jaar is (laat-Kwartêr en Holoseen), en koolstof in hulle samestelling bevat.
Hierdie voorwerpe sluit houtskool, hout, been, stuifmeel, skulpe, grondwater en kalkreet in.
Daar bestaan ’n algemene wanopvatting dat koolstof 14-datering gebruik kan word om die ouderdom van die aarde te bepaal. Dit is egter onmoontlik aangesien die halfleeftyd van die koolstof-14 (14C)-isotoop net sowat 5 715 jaar is, en dus slegs geskik is om ouderdomme van sowat 50 000 jaar of minder te bepaal. Radiodateringsmetodes waarmee geologiese tyd gemeet kan word, sluit uraan-lood (U/Pb)-, kalium-argon (K/Ar)- en rubidium-stronsium ( Rb/Sr)-radiodatering in. Hierdie tegnieke is geskik vanweë die baie lang halfleeftyd van die moederelemente.
Metode
Koolstof het twee stabiele isotope wat natuurlik voorkom: koolstof 12 (12C; 98,89%) en koolstof 13 (13C; 1,11%), asook ’n onstabiele isotoop, koolstof 14 (14C). Laasgenoemde is van groot belang, aangesien die onstabiele aard daarvan radiokoolstofdatering moontlik maak.
Koolstof 14 het ’n halfleeftyd () van 5 715 jaar en word gevorm deur kosmiese strale wat stikstof 14-isotope in die boonste atmosfeer verander in 14C-isotope. Hierdie nuut gevormde isotope word gaandeweg in die atmosferiese CO2 opgeneem. Die vergelykings is:
Vanweë die voortdurende vorming van die 14C-isotoop bly die verhouding tussen 14C en 12C redelik konstant. Hierdie verhouding bestaan ook in die CO2 wat deur plante, skulpe, diere en gesteentes opgeneem word. Wanneer die organisme doodgaan, hou dit op om koolstofdioksied CO2 (en dus 14C) op te neem. Die koolstof 14 wat voor die organisme se dood opgeneem is, verminder gaandeweg namate dit weer as gevolg van radioaktiewe verval in stikstof 14 verander met die vergelyking:
Na jaar is die aantal atome in 'n spesifieke monster wat oorspronklik monsters gehad het, deur die vergelyking
gegee waar
Wanneer ’n monster van die material (hout, been, skulpe ens.) in ’n laboratorium ontleed word, word die 14C /12C-verhouding bepaal en met die atmosferiese verhouding vergelyk. Aangesien die tempo van radioaktiewe verval bekend is en die atmosferiese verhouding redelik konstant bly, is die hoeveelheid 14C wat verdwyn het relatief tot die oorblywende 12C ’n aanduiding van die ouderdom van die monster. Dus is hierdie verhouding is ongeveeer . Deur die bogenoemde vergelykings te gebruik, kan 'n mens skat.
Bronne
Aitken, M.J. (1990). Science-based Dating in Archaeology. London: Longman. ISBN0-582-49309-9.
Aitken, Martin J. (2003). "Radiocarbon Dating". In Ellis, Linda (red.). Archaeological Method and Theory. New York: Garland Publishing. pp. 505–508.
Bianchi, Thomas S.; Canuel, Elizabeth A. (2011). Chemical Markers in Aquatic Ecosystems. Princeton: Princeton University Press. ISBN978-0-691-13414-7.
Bousman, C. Britt; Vierra, Bradley J. (2012). "Chronology, Environmental Setting, and Views of the Terminal Pleistocene and Early Holocene Cultural Transitions in North America". In Bousman, C. Britt; Vierra, Bradley J. (reds.). From the Pleistocene to the Holocene: Human Organization and Cultural Transformations in Prehistoric North America. College Station, Texas: Texas A&M University Press. pp. 1–15. ISBN978-1-60344-760-7.
Bowman, Sheridan (1995) [1990]. Radiocarbon Dating. London: British Museum Press. ISBN0-7141-2047-2.
Cronin, Thomas M. (2010). Paleoclimates: Understanding Climate Change Past and Present. New York: Columbia University Press. ISBN978-0-231-14494-0.
Dass, Chhabil (2007). Fundamentals of Contemporary Mass Spectrometry. Hoboken, New Jersey: John Wiley & Sons. ISBN978-0-471-68229-5.
Ferronsky, V.I.; Polyakov, V.A. (2012). Isotopes of the Earth's Hydrosphere. New York: Springer. ISBN978-94-007-2855-4.
Killick, David (2014). "Using evidence from natural sciences in archaeology". In Chapman, Robert; Alison, Wylie (reds.). Material Evidence: Learning From Archaeological Practice. Abingdon, UK: Routledge. pp. 159–172. ISBN978-0-415-83745-3.
L'Annunziata, Michael F. (2007). Radioactivity: Introduction and History. Amsterdam: Elsevier. ISBN978-0-444-52715-8.
L'Annunziata, Michael F.; Kessler, Michael J. (2012). "Liquid scintillation analysis: principles and practice". In L'Annunziata, Michael F. (red.). Handbook of Radioactivity Analysis (3rd uitg.). Oxford: Academic Press. pp. 423–573. ISBN978-0-12-384873-4.
Libby, Willard F. (1965) [1952]. Radiocarbon Dating (2nd (1955) uitg.). Chicago: Phoenix.
Macdougall, Doug (2008). Nature's Clocks: How Scientists Measure the Age of Almost Everything. Berkeley, California: University of California Press. ISBN978-0-520-24975-2.
Malainey, Mary E. (2010). A Consumer's Guide to Archaeological Science. New York: Springer. ISBN978-1-4419-5704-7.
Maslin, Mark A.; Swann, George E.A. (2006). "Isotopes in marine sediments". In Leng, Melanie J. (red.). Isotopes in Palaeoenvironmental Research. Dordrecht: Springer. pp. 227–290. ISBN978-1-4020-2503-7.
Mook, W.G.; Waterbolk, H.T. (1985). Handbooks for Archaeologists: No. 3: Radiocarbon Dating. Strasbourg: European Science Foundation. ISBN2-903148-44-9.
Post, Wilfred M. (2001). "Carbon cycle". In Goudie, Andrew; Cuff, David J. (reds.). Encyclopedia of Global Change: Environmental Change and Human Society, Volume 1. Oxford: Oxford University Press. pp. 127–130. ISBN0-19-514518-6.
Renfrew, Colin (2014). "Foreword". In Taylor, R.E.; Bar-Yosef, Ofer (reds.). Radiocarbon Dating. Walnut Creek, California: Left Coast Press. pp. 12–14. ISBN978-1-59874-590-0.
Schoeninger, Margaret J. (2010). "Diet reconstruction and ecology using stable isotope ratios". In Larsen, Clark Spencer (red.). A Companion to Biological Anthropology. Oxford: Blackwell. pp. 445–464. ISBN978-1-4051-8900-2.
Šilar, Jan (2004). "Application of environmental radionuclides in radiochronology: Radiocarbon". In Tykva, Richard; Berg, Dieter (reds.). Man-made and Natural Radioactivity in Environmental Pollution and Radiochronology. Dordrecht: Kluwer Academic Publishers. pp. 150–179. ISBN1-4020-1860-6.
Suess, H.E. (1970). "Bristlecone-pine calibration of the radiocarbon time-scale 5200 B.C. to the present". In Olsson, Ingrid U. (red.). Radiocarbon Variations and Absolute Chronology. New York: John Wiley & Sons. pp. 303–311.
Taylor, R.E. (1997). "Radiocarbon dating". In Taylor, R.E.; Aitken, Martin J. (reds.). Chronometric Dating in Archaeology. New York: Plenum Press. pp. 65–97. ISBN0-306-45715-6.
Taylor, R.E.; Bar-Yosef, Ofer (2014). Radiocarbon Dating (2nd uitg.). Walnut Creek, California: Left Coast Press. ISBN978-1-59874-590-0.
Terasmae, J. (1984). "Radiocarbon dating: some problems and potential developments". In Mahaney, W.C. (red.). Quaternary Dating Methods. Amsterdam: Elsevier. pp. 1–15. ISBN0-444-42392-3.
Theodórsson, Páll (1996). Measurement of Weak Radioactivity. Singapore: World Scientific Publishing. ISBN9810223153.
Trumbore, Susan E. (1996). "Applications of accelerator mass spectrometry to soil science". In Boutton, Thomas W.; Yamasaki, Shin-ichi (reds.). Mass Spectrometry of Soils. New York: Marcel Dekker. pp. 311–340. ISBN0-8247-9699-3.
Tuniz, C.; Zoppi, U.; Barbetti, M. (2004). "Radionuclide dating in archaeology by accelerator mass spectrometry". In Martini, M.; Milazzo, M.; Piacentini, M. (reds.). Physics Methods in Archaeometry. Amsterdam: IOS Press. pp. 385–405. ISBN978-1-58603-424-5.
This article uses material from the Wikipedia Afrikaans article Radiokoolstofdatering, which is released under the Creative Commons Attribution-ShareAlike 3.0 license ("CC BY-SA 3.0"); additional terms may apply (view authors). Inhoud is onderhewig aan CC BY-SA 4.0, tensy anders vermeld. Images, videos and audio are available under their respective licenses. ®Wikipedia is a registered trademark of the Wiki Foundation, Inc. Wiki Afrikaans (DUHOCTRUNGQUOC.VN) is an independent company and has no affiliation with Wiki Foundation.