Measuring the age of the Lathrop Wells volcanic center at Yucca Mountain
- Univ. of California, Riverside (United States)
- Los Alamos National Lab., Las Vegas, NV (United States)
- Univ. of New Mexico, Albuquerque (United States)
Turrin et al. argue that conventional K-Ar and {sup 40}Ar/{sup 39}Ar age determinations and paleomagnetic data provide a definitive age assignment of approximatley 136 ka (thousand years ago) to 141 ka for the Lathrop Wells volcanic center with an error of less than 10,000 years. The use of a weighted mean gives age assignments with unrealistically small errors, in that the group age dates range from 20 ka to 947 ka. Yet Turrin et al. do not explain why the weighted mean might be more reliable than the conventional mean, nor do they test the validity of the weighted mean method. Specific concerns are as follows. (1) The age determinations are positively skewed with a mean larger than the median. (2) Turrin et al. did not examine the data set with conventional tests for outliers. Evaluation of their data shows that outliers are present where outliers are defined to be more than 1.5 times the interquantile range. (3) Four age determinations were discarded by Turrin et al. in the weighted mean data reduction because of contamination. No systematic criteria were presented for doing so, and recalculation of the data set with these four age determinations yields significantly older values of the weighted mean with larger uncertainty. (4) The regression plots show the presence of influential cases which should have been identified to check for errors and suitability to the data set. (5) There was no discussion of data errors other than analytical. (6) Conventional, whole rock K-Ar data are averaged with the {sup 40}Ar/{sup 39}Ar to establish final values for the weighted means. However, the whole rock data are not listed. Thus it is not clear whether the data set belongs to the same population as the {sup 40}Ar/{sup 39}Ar data.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 138467
- Journal Information:
- Science, Journal Name: Science Journal Issue: 5069 Vol. 257; ISSN SCIEAS; ISSN 0036-8075
- Country of Publication:
- United States
- Language:
- English
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{sup 40}Ar/{sup 39}Ar laser fusion and K-Ar ages from Lathrop Wells, Nevada, and Cima, California: The age of the latest volcanic activity in the Yucca Mountain area
{sup 40}Ar/{sup 39}Ar laser fusion and K-Ar ages from Lathrop Wells, Nevada, and Cima, California: The age of the latest volcanic activity in the Yucca Mountain area
The age of Lathrop Wells volcanic center: An {sup 40}Ar/{sup 39}Ar dating investigation
Conference
·
Mon Dec 30 23:00:00 EST 1991
·
OSTI ID:145420
{sup 40}Ar/{sup 39}Ar laser fusion and K-Ar ages from Lathrop Wells, Nevada, and Cima, California: The age of the latest volcanic activity in the Yucca Mountain area
Conference
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Wed May 01 00:00:00 EDT 1991
·
OSTI ID:138103
The age of Lathrop Wells volcanic center: An {sup 40}Ar/{sup 39}Ar dating investigation
Journal Article
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Thu Dec 31 23:00:00 EST 1998
· Journal of Geophysical Research
·
OSTI ID:328584