Use of 39Ar and 14C for groundwater dating
Cosmic-ray produced atmospheric 39Ar activity (T1/2 = 269 yr) has been determined at 0.11 ±0.012 dpm/lt argon. Ice samples from two profiles in Greenland bore holes showed conclusively that 39Ar dating leads to correct ages. Corrections can be made for possible contamination of the samples with ambi...
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Arizona Board of Regents, University of Arizona
1980
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ftdatacite:10.48350/158693 2023-05-15T16:30:01+02:00 Use of 39Ar and 14C for groundwater dating Loosli, Heinz Hugo Oeschger, Hans 1980 https://dx.doi.org/10.48350/158693 https://boris.unibe.ch/158693/ unknown Arizona Board of Regents, University of Arizona restricted access publisher holds copyright http://purl.org/coar/access_right/c_16ec 570 Life sciences; biology 610 Medicine & health Text article-journal journal article ScholarlyArticle 1980 ftdatacite https://doi.org/10.48350/158693 2021-11-05T12:55:41Z Cosmic-ray produced atmospheric 39Ar activity (T1/2 = 269 yr) has been determined at 0.11 ±0.012 dpm/lt argon. Ice samples from two profiles in Greenland bore holes showed conclusively that 39Ar dating leads to correct ages. Corrections can be made for possible contamination of the samples with ambient air during field extraction and during laboratory processing by measuring 85Kr in the same samples. The following isotopes: 14C, 39Ar, 85Kr, 3H, partly 32Si, 13C, and 18O were investigated in 20 groundwater samples. Unexpectedly large discrepancies between “14C ages” and “39Ar ages” were observed for many of these samples. For example, a horizontal profile of a confined sandstone aquifer in the Franconian Albvorland showed decreasing 39Ar and 14C activities from respectively, 100 percent to 17 percent and 80 percent to 0.3 percent of modern activity, corresponding to elapsed time periods of 700 and >20,000 years, respectively. It seems unlikely that gas exchange through the aquiclude is the cause of this discrepancy. It can neither be explained by only assuming that the water represents a mixing of components with different ages. We detected the possibility of underground production of 39Ar in thermal spring water from Zurzach, Switzerland. Its argon showed higher specific activity than atmospheric argon. Elsewhere, however, samples were found containing no detectable 39Ar activity: two wells of a confined carstic aquifer in Ingolstadt, Germany, show less than 7 percent atmospheric activity. In our opinion, the assumptions on which the 14C method in hydrology are based need to be critically re-examined. It is possible that for some aquifers carbonate exchange between solid and liquid phases in the aquifer changes 14C results to a larger degree than generally assumed. Text Greenland DataCite Metadata Store (German National Library of Science and Technology) Greenland |
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570 Life sciences; biology 610 Medicine & health |
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570 Life sciences; biology 610 Medicine & health Loosli, Heinz Hugo Oeschger, Hans Use of 39Ar and 14C for groundwater dating |
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570 Life sciences; biology 610 Medicine & health |
description |
Cosmic-ray produced atmospheric 39Ar activity (T1/2 = 269 yr) has been determined at 0.11 ±0.012 dpm/lt argon. Ice samples from two profiles in Greenland bore holes showed conclusively that 39Ar dating leads to correct ages. Corrections can be made for possible contamination of the samples with ambient air during field extraction and during laboratory processing by measuring 85Kr in the same samples. The following isotopes: 14C, 39Ar, 85Kr, 3H, partly 32Si, 13C, and 18O were investigated in 20 groundwater samples. Unexpectedly large discrepancies between “14C ages” and “39Ar ages” were observed for many of these samples. For example, a horizontal profile of a confined sandstone aquifer in the Franconian Albvorland showed decreasing 39Ar and 14C activities from respectively, 100 percent to 17 percent and 80 percent to 0.3 percent of modern activity, corresponding to elapsed time periods of 700 and >20,000 years, respectively. It seems unlikely that gas exchange through the aquiclude is the cause of this discrepancy. It can neither be explained by only assuming that the water represents a mixing of components with different ages. We detected the possibility of underground production of 39Ar in thermal spring water from Zurzach, Switzerland. Its argon showed higher specific activity than atmospheric argon. Elsewhere, however, samples were found containing no detectable 39Ar activity: two wells of a confined carstic aquifer in Ingolstadt, Germany, show less than 7 percent atmospheric activity. In our opinion, the assumptions on which the 14C method in hydrology are based need to be critically re-examined. It is possible that for some aquifers carbonate exchange between solid and liquid phases in the aquifer changes 14C results to a larger degree than generally assumed. |
format |
Text |
author |
Loosli, Heinz Hugo Oeschger, Hans |
author_facet |
Loosli, Heinz Hugo Oeschger, Hans |
author_sort |
Loosli, Heinz Hugo |
title |
Use of 39Ar and 14C for groundwater dating |
title_short |
Use of 39Ar and 14C for groundwater dating |
title_full |
Use of 39Ar and 14C for groundwater dating |
title_fullStr |
Use of 39Ar and 14C for groundwater dating |
title_full_unstemmed |
Use of 39Ar and 14C for groundwater dating |
title_sort |
use of 39ar and 14c for groundwater dating |
publisher |
Arizona Board of Regents, University of Arizona |
publishDate |
1980 |
url |
https://dx.doi.org/10.48350/158693 https://boris.unibe.ch/158693/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_rights |
restricted access publisher holds copyright http://purl.org/coar/access_right/c_16ec |
op_doi |
https://doi.org/10.48350/158693 |
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1766019727380971520 |