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Gravitational Enrichment of ^(84)Kr/^(36)Ar Ratios in Polar Ice Caps: A Measure of Firn Thickness and Accumulation Temperature

Craig, H. and Wiens, R. C. (1996) Gravitational Enrichment of ^(84)Kr/^(36)Ar Ratios in Polar Ice Caps: A Measure of Firn Thickness and Accumulation Temperature. Science, 271 (5256). pp. 1708-1710. ISSN 0036-8075. http://resolver.caltech.edu/CaltechAUTHORS:20141216-082509059

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Abstract

Measurements of ^(84)Kr/^(36)Ar ratios in Greenland ice show that gravitational separation in the firn layer is responsible for the enrichments relative to atmospheric ratios. The ^(84)Kr/^(36)Ar ratio is enriched by 12.8 per mil and is 24 times the ^(18)O/^(16)O enrichment in trapped O_2, as predicted for gravitational fractionation. Because gravitational enrichment depends on firn thickness, which in turn depends on annual mean temperature, noble gas ratios provide a method for determining paleotemperatures and ancient firn thicknesses in polar ice caps. The gravitational effects are modulated by about 10 to 15 percent by atmospheric concentration changes caused by temperature effects on oceanic gas solubilities. The availability of five noble gases should make it possible to deconvolute the solubility and gravitational enrichments for calibration of ^(18)O paleotemperatures throughout the polar ice sheets.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1126/science.271.5256.1708DOIArticle
http://www.sciencemag.org/content/271/5256/1708PublisherArticle
http://www.jstor.org/stable/2890831JSTORArticle
ORCID:
AuthorORCID
Wiens, R. C.0000-0002-3409-7344
Alternate Title:Gravitational Enrichment of 84Kr/36Ar Ratios in Polar Ice Caps: A Measure of Firn Thickness and Accumulation Temperature
Additional Information:© 1996 American Association for the Advancement of Science Received 13 July 1995; accepted 17 January 1996. We thank J. Welhan and the members of the PICO group for drilling the Dye 3 ice core, D. Burtner for laboratory assistance, K. Turekian for discussion, and C. C. Langway Jr. for his interest in and enthusiasm for our ice-core work. R. Keeling pointed out to us that atmospheric concentrations will be affected by global temperature changes. Supported by the Polar Programs Office of NSF.
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Record Number:CaltechAUTHORS:20141216-082509059
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141216-082509059
Official Citation:Gravitational Enrichment of 84Kr/36Ar Ratios in Polar Ice Caps: A Measure of Firn Thickness and Accumulation Temperature H. Craig and R. C. Wiens Science 22 March 1996: 271 (5256), 1708-1710. [DOI:10.1126/science.271.5256.1708]
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52842
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Dec 2014 17:18
Last Modified:29 Apr 2019 20:23

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