Eocene calibration of geomagnetic polarity time scale reevaluated: Evidence from the Green River Formation of Wyoming

Publication Status is "Submitted" Or "In Press: 
Yes
LDEO Publication: 
Yes
Publication Type: 
Journal Article
Year of Publication: 
2004
Authors: 
Machlus, M.; Hemming, S. R.; Olsen, P. E.; Christie-Blick, N.
Editor: 
Journal Title: 
Geology
Journal Date: 
Feb
Place Published: 
Tertiary Title: 
Volume: 
32
Issue: 
2
Pages: 
137-140
Section / Start page: 
Publisher: 
ISBN Number: 
0091-7613
ISSN Number: 
Edition: 
Short Title: 
Accession Number: 
ISI:000188842500011
LDEO Publication Number: 
6531
Call Number: 
Key Words: 
green river formation; eocene; ar/ar; lacustrine; wasatchian-bridgerian; early eocene climatic optimum; middle eocene; bighorn basin; north-america; boundary; magnetostratigraphy; geochronology; age;
Abstract: 

We reevaluate the Eocene geomagnetic polarity time scale on the basis of single-crystal Ar-40/Ar-39 ages for air-fall tuffs from the Wilkins Peak Member of the Green River Formation of Wyoming. Tuff 6 is dated as 49.1 +/- 0.2 Ma, and tuff 3 is dated as 50.4 +/- 0.3 Ma (maximum estimate). When combined with published magnetostratigraphic constraints, these age determinations suggest that the currently accepted age of chron C22r is 1.5-2.5 m.y. too old, which supports a significantly longer duration for the early Eocene, for the early Eocene climatic optimum, and the Wasatchian North American Land Mammal Age.

Notes: 

772LCTimes Cited:10Cited References Count:24

URL: 
<Go to ISI>://000188842500011
DOI: 
Doi 10.1130/G20091.1