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(U-Th)/He Dating: Techniques, Calibrations, and Applications

Farley, Kenneth A. (2002) (U-Th)/He Dating: Techniques, Calibrations, and Applications. In: Noble Gases in Geochemistry and Cosmochemistry. Reviews in Mineralogy and Geochemistry. No.47. Mineralogical Society of America , Washington, DC, pp. 819-844. ISBN 9780939950591. https://resolver.caltech.edu/CaltechAUTHORS:20121116-080830444

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Abstract

The possibility of dating minerals by the accumulation of ^4He from U and Th decay has been recognized for many years (e.g., Strutt 1905), but in the century since the idea was first conceived, the method has rarely been applied successfully. After several investigations of (U-Th)/He dating of various minerals (e.g., Damon and Kulp 1957; Fanale and Kulp 1962; Damon and Green 1963; Turekian et al. 1970; Bender 1973; Leventhal 1975; Ferreira et al. 1975) the technique was essentially abandoned as yielding unreliable and usually low ages, presumably as a result of diffusive He loss possibly associated with radiation damage. In 1987, Zeitler and coworkers rekindled interest in the method by proposing that in the case of apatite, He ages might be meaningfully interpreted as ages of cooling through very low temperatures. Laboratory diffusion data presented by these authors indicated a closure temperature of about 100ºC, a value supported by more recent studies (Lippolt et al. 1994; Wolf et al. 1996b; Warnock et al. 1997). Consistent with this interpretation Wolf et al. (1996a) found that apatite He ages increase systematically with sample elevation in a mountain range, as expected for exhumation-induced cooling through a low closure temperature. Based on the strength of these results and additional laboratory (Farley 2000) and natural (Warnock et al. 1997; House et al. 1999; Stockli et al. 2000) constraints on He diffusivity, recent attention has focused on applications of apatite He thermochronometry. There is also renewed interest in He dating of other U- and Th-bearing minerals both for dating mineral formation and for thermochronometry. For example, Lippolt and coworkers have undertaken detailed studies of He diffusion and dating of various phases, most notably hematite formed in hydrothermal systems (Lippolt and Weigel 1988; Wernicke and Lippolt 1992; Lippolt et al. 1993; Wernicke and Lippolt 1994a,b). Here I present an overview of recent techniques, calibrations, and applications of the (U-Th)/He dating method; Hurley (1954) provides an excellent summary of earlier work in this field. Much of this paper focuses on apatite, because the He behavior and requisite analytical techniques are better established for this phase than for other target minerals, such as zircon and titanite. Similarly, much of this paper concerns He diffusivity behavior required for thermochronometric applications, yet recent work is also considering applications to direct dating, for example, of young tephras (Farley et al. 2001).


Item Type:Book Section
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URLURL TypeDescription
http://dx.doi.org/10.2138/rmg.2002.47.18 DOIUNSPECIFIED
http://rimg.geoscienceworld.org/content/47/1/819PublisherUNSPECIFIED
ORCID:
AuthorORCID
Farley, Kenneth A.0000-0002-7846-7546
Additional Information:© 2002 Mineralogical Society of America. Many members of my research group, especially M. House, P. Reiners, D. Stockli, and R. Wolf, contributed substantially to the ideas and content of this paper. This work was supported by the National Science Foundation and by a fellowship award from the David and Lucille Packard Foundation. Fin Stuart, Raphael Pik and Tibor Dunai provided helpful reviews.
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David and Lucille Packard FoundationUNSPECIFIED
Series Name:Reviews in Mineralogy and Geochemistry
Issue or Number:47
Record Number:CaltechAUTHORS:20121116-080830444
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121116-080830444
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35500
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Nov 2012 22:26
Last Modified:03 Mar 2020 13:01

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