Abstract
One of the largest and most important extensional structures in the Bitterroot complex is the Bitterroot mylonite zone. An undeformed rhyolitic dike that transects mylonitic fabrics in the southern part of the zone yields a 40Ar/39Ar K-feldspar age of 46.4±0.8 Ma, establishing a minimum age for the structure. Previously published U-Pb data for deformed granitoids from other parts of the shear zone suggest that the maximum age of mylonitization is 48±1 Ma. Documentation of 46-48 extension in the Bitterroot complex suggests simultaneous deformation in the Rocky Mountains Basin and Range and Omineca extensional provinces and reinforces the idea that the Lewis and Clark fault system may have acted as an extensional transfer zone in middle Eocene time. -from Authors
| Original language | English (US) |
|---|---|
| Pages (from-to) | 161-164 |
| Number of pages | 4 |
| Journal | Geology |
| Volume | 21 |
| Issue number | 2 |
| DOIs | |
| State | Published - 1993 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Geology
Cite this
Age of Tertiary extension in the Bitterroot metamorphic core complex, Montana and Idaho. / Hodges, Kip; Applegate, J. D.
In: Geology, Vol. 21, No. 2, 1993, p. 161-164.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Age of Tertiary extension in the Bitterroot metamorphic core complex, Montana and Idaho
AU - Hodges, Kip
AU - Applegate, J. D.
PY - 1993
Y1 - 1993
N2 - One of the largest and most important extensional structures in the Bitterroot complex is the Bitterroot mylonite zone. An undeformed rhyolitic dike that transects mylonitic fabrics in the southern part of the zone yields a 40Ar/39Ar K-feldspar age of 46.4±0.8 Ma, establishing a minimum age for the structure. Previously published U-Pb data for deformed granitoids from other parts of the shear zone suggest that the maximum age of mylonitization is 48±1 Ma. Documentation of 46-48 extension in the Bitterroot complex suggests simultaneous deformation in the Rocky Mountains Basin and Range and Omineca extensional provinces and reinforces the idea that the Lewis and Clark fault system may have acted as an extensional transfer zone in middle Eocene time. -from Authors
AB - One of the largest and most important extensional structures in the Bitterroot complex is the Bitterroot mylonite zone. An undeformed rhyolitic dike that transects mylonitic fabrics in the southern part of the zone yields a 40Ar/39Ar K-feldspar age of 46.4±0.8 Ma, establishing a minimum age for the structure. Previously published U-Pb data for deformed granitoids from other parts of the shear zone suggest that the maximum age of mylonitization is 48±1 Ma. Documentation of 46-48 extension in the Bitterroot complex suggests simultaneous deformation in the Rocky Mountains Basin and Range and Omineca extensional provinces and reinforces the idea that the Lewis and Clark fault system may have acted as an extensional transfer zone in middle Eocene time. -from Authors
UR - http://www.scopus.com/inward/record.url?scp=84879879985&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84879879985&partnerID=8YFLogxK
U2 - 10.1130/0091-7613(1993)021<0161:AOTEIT>2.3.CO;2
DO - 10.1130/0091-7613(1993)021<0161:AOTEIT>2.3.CO;2
M3 - Article
VL - 21
SP - 161
EP - 164
JO - Geology
JF - Geology
SN - 0091-7613
IS - 2
ER -