Title: Limits on the tectonic significance of rapid cooling events in extensional settings: Insights from the Bitterroot metamorphic core complex, Idaho-Montana
Abstract: Research Article| November 01, 1994 Limits on the tectonic significance of rapid cooling events in extensional settings: Insights from the Bitterroot metamorphic core complex, Idaho-Montana M. A. House; M. A. House 1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Search for other works by this author on: GSW Google Scholar K. V. Hodges K. V. Hodges 1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Search for other works by this author on: GSW Google Scholar Author and Article Information M. A. House 1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 K. V. Hodges 1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1994) 22 (11): 1007–1010. https://doi.org/10.1130/0091-7613(1994)022<1007:LOTTSO>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation M. A. House, K. V. Hodges; Limits on the tectonic significance of rapid cooling events in extensional settings: Insights from the Bitterroot metamorphic core complex, Idaho-Montana. Geology 1994;; 22 (11): 1007–1010. doi: https://doi.org/10.1130/0091-7613(1994)022<1007:LOTTSO>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Rapid cooling events deduced from thermochronologic data are often interpreted to be coincident with the age of extensional denudation in metamorphic core complexes. 40Ar/39Ar data for mylonitic and nonmylonitic footwall rocks from the Bitterroot core complex, Idaho-Montana, United States, challenge this view. Previous work brackets the age of the principal detachment in this area, the Bitterroot mylonite zone, between 48 ± 1 and 46.4 ± 0.8 Ma. Newly obtained hornblende 40Ar/39Ar cooling ages for samples collected from the mylonite zone are within this age range, consistent with mylonitization at amphibolite facies conditions. However, muscovite, biotite, and potassium feldspar 40Ar/39Ar ages of ∼45-40 Ma for rocks from the same area define a rapid cooling event that is significantly younger than the Bitterroot mylonite zone. If the 45-40 Ma event is related to tectonic denudation by movement on the detachment, then we can infer 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 40Ar/39Ar data from the footwalls of metamorphic core complexes to suggest the precise age of tectonic denudation. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Publication Year: 1994
Publication Date: 1994-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 30
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