Universität zu Köln

Phillips, Fred M., Argento, David C., Balco, Greg, Caffee, Marc W., Clem, John, Dunai, Tibor J., Finkel, Robert, Goehring, Brent, Gosse, John C., Hudson, Adam M., Jull, A. J. Timothy, Kelly, Meredith A., Kurz, Mark, Lal, Devendra, Lifton, Nathaniel ORCID: 0000-0002-6976-3298, Marrero, Shasta M., Nishiizumi, Kunihiko, Reedy, Robert C., Schaefer, Joerg, Stone, John O. H., Swanson, Terry and Zreda, Marek G. (2016). The CRONUS-Earth Project: A synthesis. Quat. Geochronol., 31. S. 119 - 155. OXFORD: ELSEVIER SCI LTD. ISSN 1878-0350

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Abstract

Geological surface-exposure dating using cosmogenic-nuclide accumulation became a practical geochronological endeavor in 1986, when the utility of Be-10, Al-26, Cl-36, and He-3 were all demonstrated. In response to the lack of a common basis for quantifying analytical consistency and calibrating cosmogenic-nuclide production, the CRONUS-Earth Project in the U.S. was started in 2005, along with a European partner project, CRONUS-EU. The goal of the CRONUS-Earth Project was to improve the accuracy and precision of terrestrial cosmogenic nuclide dating in general, focusing especially on nuclide production rates and their variation with altitude, latitude, and time, and to attempt to move from empirically based methods to ones with a stronger basis in physics. The CRONUS-Earth Project conducted extensive intercomparisons of reference materials to attempt to quantify analytical reproducibility at the community level. We found that stated analytical uncertainties nearly always underestimate the actual degree of variability, as quantified by the over-all coefficient of variation of the intercalibration data. The average amount by which the actual coefficient of variation exceeded the analytical uncertainty was a factor of two (100%), but ranged from 15% to 300% depending on the nuclide and material. Coefficients of variation ranged from 3-4% for Be-10 to 6-8% for Cl-36, C-14, and Ne-21, to 5-11% for Al-26. Both interlaboratory bias and within-laboratory excess spread of the data played a role in increasing variability above the stated analytical uncertainties. The physical basis for cosmogenic nuclide production was investigated through numerical modeling and the measurement of energy-dependent neutron cross sections for nuclide interactions. We formulated new, physically based, scaling models, denoted LSD and LSDn, by generalizing global numerical simulations of cosmic-ray processes. The CRONUS-Earth Project identified new geological calibration sites, including one at low latitude and high elevation (Huancane, Peru), and replicated nuclide measurement at numerous laboratories. At many sites multiple nuclides were measured, providing much more confidence in the equivalence of surface-exposure ages calculated from differing nuclides. The data were interpreted using an original cosmogenic-nuclide calculator, CRONUScalc, that incorporates the new physically based scaling. The new data and model produced significantly better fits than previous efforts, but do not fully resolve apparent spatial variations in production rates. The CRONUS-Earth and CRONUS-EU Projects have provided a firm foundation for assessing the strengths and weaknesses of cosmogenic-nuclide analytical methods, adjusted the AMS standards for Be-10 and consequently revised the half-life, and have provided improved calibration data sets and interpretative tools. (C) 2015 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Phillips, Fred M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Argento, David C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Balco, Greg UNSPECIFIED UNSPECIFIED UNSPECIFIED Caffee, Marc W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Clem, John UNSPECIFIED UNSPECIFIED UNSPECIFIED Dunai, Tibor J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Finkel, Robert UNSPECIFIED UNSPECIFIED UNSPECIFIED Goehring, Brent UNSPECIFIED UNSPECIFIED UNSPECIFIED Gosse, John C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hudson, Adam M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Jull, A. J. Timothy UNSPECIFIED UNSPECIFIED UNSPECIFIED Kelly, Meredith A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kurz, Mark UNSPECIFIED UNSPECIFIED UNSPECIFIED Lal, Devendra UNSPECIFIED UNSPECIFIED UNSPECIFIED Lifton, Nathaniel UNSPECIFIED orcid.org/0000-0002-6976-3298 UNSPECIFIED Marrero, Shasta M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Nishiizumi, Kunihiko UNSPECIFIED UNSPECIFIED UNSPECIFIED Reedy, Robert C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schaefer, Joerg UNSPECIFIED UNSPECIFIED UNSPECIFIED Stone, John O. H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Swanson, Terry UNSPECIFIED UNSPECIFIED UNSPECIFIED Zreda, Marek G. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-286838
DOI:	10.1016/j.quageo.2015.09.006
Journal or Publication Title:	Quat. Geochronol.
Volume:	31
Page Range:	S. 119 - 155
Date:	2016
Publisher:	ELSEVIER SCI LTD
Place of Publication:	OXFORD
ISSN:	1878-0350
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PRODUCTION-RATE CALIBRATION; HE-3 PRODUCTION-RATES; BE-10 PRODUCTION-RATE; NUCLIDE PRODUCTION-RATES; COSMOGENIC CL-36 PRODUCTION; RAY INDUCED NEUTRONS; HOLOCENE LAVA FLOWS; MASS-SPECTROMETRY; ENERGY-SPECTRUM; SCALING FACTORS Multiple languages Geography, Physical; Geosciences, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/28683