Abstract
Rapid cooling events deduced from thermochronologic data are often interpreted to be coincident with the age of extensional denudation in metamorphic core complexes. 40 Ar/ 39 Ar data for mylonitic and nonmylonitic footwall rocks from the Bitterroot core complex, Idaho-Montana, US, Challenge this view. Newly obtained hornblende 40 Ar/ 39 Ar cooling ages for samples collected from the mylonite zone suggest a time lag of ~1-3 m.y. between the age of unroofing and the time of thermal reequilibration. These data suggest caution in the use of 40 Ar/ 39 Ar data from the footwalls of metamorphic core complexes to suggest the precise age of tectonic denudation. -from Authors
Original language | English (US) |
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Pages (from-to) | 1007-1010 |
Number of pages | 4 |
Journal | Geology |
Volume | 22 |
Issue number | 11 |
DOIs | |
State | Published - Jan 1 1994 |
Externally published | Yes |
ASJC Scopus subject areas
- Geology