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GEOREF RECORD

First successful (super 40) Ar- (super 39) Ar dating of glauconies; argon recoil in single grains of cryptocrystalline material

P. E. Smith, N. M. Evensen and D. York
First successful (super 40) Ar- (super 39) Ar dating of glauconies; argon recoil in single grains of cryptocrystalline material
Geology (Boulder) (January 1993) 21 (1): 41-44

Abstract

Potassium-argon dating of glaucony, one of the few widely occurring authigenic materials in the sedimentary record, has provided a large percentage of the dates used for the calibration of the geologic time scale. This material has been considered unsuitable for (super 40) Ar- (super 39) Ar dating because of the large losses of neutron-induced (super 39) Ar during or subsequent to irradiation of samples. We have measured recoiled (super 39) Ar and (super 37) Ar from single grains of glaucony (100-350 mu m in diameter). Irradiations were done both in air and in vacuo by using a microampoule technique of encapsulation. The observed in vacuo behavior of recoiled atoms can be readily understood by a simple model of their interaction with the network of very fine laminae composing the grains. When the microampoule technique is used, the integrated (super 40) Ar- (super 39) Ar ages and their associated precision compare very favorably with conventional K-Ar results. Because glauconies are inherently heterogeneous populations, owing to their complex evolution, it is anticipated that single-grain (super 40) Ar- (super 39) Ar dating may lead to significant refinements in the geologic time scale, especially for the Cenozoic.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 21
Serial Issue: 1
Title: First successful (super 40) Ar- (super 39) Ar dating of glauconies; argon recoil in single grains of cryptocrystalline material
Affiliation: University of Toronto, Department of Physics, Toronto, ON, Canada
Pages: 41-44
Published: 199301
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 14
Accession Number: 1993-001187
Categories: Geochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1993
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