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Cross-References TERRESTRIAL COSMOGENIC NUCLIDE DATING TERRESTRIAL COSMOGENIC NUCLIDE DATING 799 in central and northern Europe. Bulletin of the Geological Soci- Changbaishan, northeastern China. Quaternary Science ety of America, 96, 1554–1571. Reviews, 47, 150–159. Vandergoes, M. J., Hogg, A. G., Lowe, D. J., Newnham, R. M., Zalasiewicz, J., Cita, M. B., Hilgen, F., Pratt, B. R., Strasser, A., Denton, G. H., Southon, J., Barrell, D. J. A., Blaauw, M., Wilson, Thierry, J., and Weissert, H., 2013. Chronostratigraphy and geo- C. J. N., McGlone, M. S., Allan, A. S. R., Almond, P. C., chronology: a proposed realignment. GSA Today, 23,4–8. Petchey, F., Dalbell, K., and Dieffenbacher-Krall, A. C., 2013. Zdanowicz, C. M., Zielinski, G. A., and Germani, M. S., 1999. A revised age for the Kawakawa/Oruanui tephra, a key marker Mount Mazama eruption: calendrical age verified and atmo- for the Last Glacial Maximum in New Zealand. Quaternary Sci- spheric impact assessed. Geology, 27, 621–624. ence Reviews, 74, 195–200. Westgate, J. A., 1989. Isothermal plateau fission track ages of hydrated glass shards from silicic tephra beds. Earth and Plane- Cross-references – tary Science Letters, 95, 226 234. Accelerator Mass Spectrometry Westgate, J. A., Smith, D. G. W., and Nichols, H., 1969. Late Qua- Ar–Ar and K–Ar Dating ternary pyroclastic layers in the Edmonton area, Alberta. In Biostratigraphy Pawluk, S. (ed.), Pedology and Quaternary Research. Edmon- 14 – C in Plant Macrofossils ton: University of Alberta, pp. 179 186. Dendrochronology, Volcanic Eruptions Westgate, J. A., Stemper, B. A., and Péwé, T. L., 1990. A 3 m.y. Fission Track Dating and Thermochronology record of Pliocene-Pleistocene loess in interior Alaska. Geology, – Ice Cores 18, 858 861. Laser Ablation Inductively Coupled Mass Spectrometer (LA ICP- Westgate, J., Shane, P., Pearce, N., Perkins, W., Korisettar, R., MS) Chesner, C. A., Williams, M., and Acharyya, S. K., 1998. All Lacustrine Environments (14C) Toba tephra occurrences across Peninsular India belong to the – Luminescence Dating 75,000 yr B.P. eruption. Quaternary Research, 50, 107 112. Magnetostratigraphic Dating Westgate, J. A., Preece, S. J., Froese, D. G., Pearce, N. J. G., Marine Isotope Stratigraphy Roberts, R. G., Demuro, M., Hart, W. K., and Perkins, W., Paleosol 2008. Changing ideas on the identity and stratigraphic signifi- 210Pb Dating cance of the Sheep Creek tephra beds in Alaska and the Yukon Peat (14C) Territory, northwestern North America. Quaternary Interna- – Radiocarbon Dating tional, 178, 183 209. Sedimentary Rocks (Rb-Sr Geochronology) Westgate, J. A., Pearce, N. J. G., Perkins, W. T., Shane, P. A. R., and Single-Crystal Laser Fusion Preece, S. J., 2011. Lead isotope ratios of volcanic glass by laser Uranium–Lead, Zircon ablation inductively-coupled plasma mass spectrometry: appli- U–Th/He Dating cation to Miocene tephra beds in Montana, USA and adjacent – Volcanic Glass (Fission Track) areas. Quaternary International, 246,89 96. Zircon Westgate, J. A., Pearce, G. W., Preece, S. J., Schweger, C. E., Morlan, R. E., Pearce, N. J. G., and Perkins, W. T., 2013a. Tephrochronology, magnetostratigraphy and mammalian faunas of Middle and Early Pleistocene sediments at two sites on the Old Crow River, northern Yukon Territory, Canada. Quaternary TERRESTRIAL COSMOGENIC NUCLIDE DATING Research, 79,75–85. Westgate, J. A., Naeser, N. D., and Alloway, B. V., 2013b. Fission- 1 2 track dating. In Elias, S. A., and Mock, C. J. (eds.), The Encyclo- John Gosse and Jeff Klein paedia of Quaternary Science, 2nd edn. Amsterdam: Elsevier, 1Department of Earth Sciences, Dalhousie University, Vol. 1, pp. 643–662. Halifax, NS, Canada Westgate, J. A., Pearce, N. J. G., Perkins, W. T., Preece, S. J., 2Department of Physics and Astronomy, University of Chesner, C. A., and Muhammad, R. F., 2013c. Tephrochronology of the Toba tuffs: four primary glass Pennsylvania, Philadelphia, PA, USA populations define the 75 ka Youngest Toba Tuff, northern Sumatra, Indonesia. Journal of Quaternary Science, 28, Synonyms – 772 776. Burial dating; Cosmic ray exposure (CRE) dating; White, J. F. L., and Houghton, B. F., 2006. Primary volcaniclastic rocks. Geology, 34, 677–680. Cosmogenic nuclide isochron dating; Cosmogenic radio- Wilson, C. J. N., Gravley, D. M., Leonard, G. S., and Rowland, J. V., nuclide (CRN) dating; Depth profile dating; Surface expo- 2009. Volcanism in the central Taupo Volcanic Zone, New sure dating (SED); Terrestrial in situ cosmogenic nuclide Zealand: tempo, styles and controls. In Thordarson, T., Self, S., (TCN) exposure histories Larsen, G., Rowland, S. K., and Hoskuldsson, A. (eds.), Studies in Volcanology: The Legacy of George Walker. London: Geolog- ical Society. Special publications of IAVCEI, Vol. Definitions 2, pp. 225–247. Cosmic rays are high-energy (104 to 1020 eV) particles Wilson, C. J. N., Charlier, B. L. A., Rowland, J. V., and Browne, composed mostly (90 %) of atomic nuclei but with some P. R. L., 2010. U-Pb dating of zircon in subsurface, hydrother- photons (gamma rays), electrons, and positrons. The mally altered pyroclastic deposits and implications for subsi- majority (90 %) of the atomic nuclei are protons dence in a magmatically active rift: Taupo Volcanic Zone, New Zealand. Journal of Volcanology and Geothermal Research, (H nuclei), the rest are alpha particles (He nuclei, 9 %) 191,69–78. and nuclei heavier atoms (1 %). Two major sources of this Yin, J., Jull, A. J. T., Burr, G. S., and Zheng, Y., 2012. A wiggle- primary cosmic radiation are the Sun whose flux peaks match age for the Millennium eruption of Tianchi Volcano at at ~100 MeV (solar cosmic rays, SCR) and our galaxy, 800 TERRESTRIAL COSMOGENIC NUCLIDE DATING the Milky Way, with the flux peak between 300 MeV and of burial. Examples of applications of cosmogenic 1 Gev (galactic cosmic rays, GCR). We believe GCR is nuclides that are produced in situ, but not in Earth’s litho- produced primarily in supernova events (an inference sphere, include surface exposure dating on Martian suggested by the excess over cosmic abundance of heavy (Farley et al., 2014) and lunar surfaces (Drozd nuclei). et al., 1974) and the size and exposure history of meteor- Secondary cosmic radiation (or “secondaries”) refers to ites (Eugster et al., 2006). Cosmogenic nuclides produced the cascade of particles produced by the interaction of pri- in the atmosphere include 14C (thermal-neutron capture by mary cosmic rays with the atmosphere and the surface of N). Radiocarbon dating has been widely applied for dating the Earth. Because of the high energies of the incoming objects of importance in defining geologic and particles, a wide spectrum of hadrons, mesons, and leptons archaeologic chronologies; in testing the authenticity of are produced. The lifetimes of many of these secondary objects of art, or worship, or historic significance; and, particles are so short that they decay in a shower of lighter on even shorter time scales, in studying the inception particles before they can interact with another atom of the and progress of disease in a living organism. 14C has been material through which they are passing, but others do used to study atmospheric mixing, verify the global circu- interact, producing yet another cascade. Ultimately, the lation model of the oceans, and follow the fate of anthro- flux is dominated by the longer-lived particles and by pogenic carbon in the biosphere and oceans. 36Cl the particles with small interaction cross sections. By the produced in the atmosphere by cosmic ray-induced spall- time the primaries have passed through 10 % of the atmo- ation of argon has been used primarily by hydrologists sphere, the secondary flux is predominately pions, kaons, to study the recharge histories of hydrologic systems. protons, neutrons, muons, electrons, positrons, and 10Be and 7Be produced in the atmosphere have been used gamma rays (photons). These secondaries will produce to estimate ages of soils and ground ice (e.g., Gilichinsky larger nuclei (cosmogenic nuclides) in the atmosphere et al., 2007) or rates of erosion of catchments (Brown and minerals. et al., 1988) and study the behavior of aerosol deposition Cosmogenic nuclides are produced through any inter- and air mass mixing. action of primary or secondary cosmic radiation with mat- Broadly, there are three types of systems that are dated ter. While some notable cosmogenic nuclides (isotopes) using cosmogenic nuclides: (1) those in which the cosmo- are produced from SCR (e.g., atmospheric radiocarbon is genic nuclide is produced in situ in a solid, e.g., 10Be in produced from low-energy (thermal) neutron capture by rock; (2) closed systems in which the in situ production nitrogen: 14N(n, p)14C), the majority of TCN production has stopped because of the complete shielding of a sample is through spallation of a target nucleus which requires from cosmic rays, e.g., 26Al/10Be in deeply buried quartz; GCR primaries or secondaries with sufficient energy to and (3) a now-closed system that formerly was in equilib- exceed the binding energy of the target nucleus rium with a reservoir that had a constant or known concen- (a minimum of >3 MeV per target nucleon). Cosmogenic tration of a cosmogenic nuclide, e.g., 14Cinany biogenic nuclides need to be distinguished from radiogenic and material; the reservoir is either the atmosphere or ocean. nucleogenic nuclides. A radiogenic nuclide is a daughter This entry treats the open system and closed system product of a radioactive decay (fission, beta, alpha). (1 and 2) applications of nuclides specifically produced For U-dating methods or (U–Th)/He thermochronology, in exposed minerals near Earth’s surface, to determine 234Th + 4He are radiogenic products of the a-decay of an exposure age of a surface, burial duration of minerals, 238U. A nucleogenic nuclide is produced when an ener- or erosion rate of surfaces and catchments (Lal, 1991). getic radiogenic particle interacts with another nucleus The term terrestrial in situ cosmogenic nuclide (TCN ) just after decay of its parent.
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