Thermochronologic constraints on mylonite and detachment fault development, Kettle Highlands, northeastern Washington and southern British Columbia
- Geological Survey, Denver, CO (United States)
The Kettle dome, northeastern Washington and southern British Columbia, is one of several large metamorphic core complexes in the region. New Ar-40/Ar-39 cooling dates from the mylonite immediately beneath the Kettle River detachment fault at Barney's Junction, a cross-cutting mafic dike, and the youngest Eocene lavas in the Republic graben set constraints on kinematic models of the tectonic evolution of the dome and related grabens: Amphibolite--hornblende (59.0 [+-] 0.2); Pegmatite--muscovite (49.3 [+-] 0.2); Pegmatite--K-feldspar (49.2 [+-] 1); Augen gneiss--K-feldspar (48.0 [+-] 1); Mafic dike--hornblende (54.5 [+-] 0.1) and biotite (49.6 [+-] 0.1); Klondike Mt. Formation lava--feeder dike (48.8 [+-] 1). The authors interpret the dates to indicate that the tectonized amphibolite, part of a Cretaceous and older metamorphosed terrane, had formed and cooled to [approx] 500 C by Late Paleocene, the mylonite zone was being domed above the ductile zone by Early Eocene at the time of emplacement of the dike--temporally equivalent to the Keller Butte suite, Eocene Colville batholith--which crosscuts the mylonite, and incipient rifting was occurring in the Republic graben as evidenced by dike swarms. The mylonite complex reached 300 C by 49Ma coincident with the termination of Sanpoil volcanism, and then cooled rapidly to near or below 150 C by 48 Ma. At about this time, mafic Klondike Mt. lavas mark the termination of Republic graben rifting and possibly detachment faulting along the Kettle River fault.
- OSTI ID:
- 6136097
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
Geology and geochronology of the southeast border of the Bitterroot dome: implications for the structural evolution of the mylonitic carapace
Geologic study of Kettle dome, northeast Washington. Final report
Related Subjects
580000* -- Geosciences
AGE ESTIMATION
ARGON 39
ARGON 40
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BRITISH COLUMBIA
CANADA
DEVELOPED COUNTRIES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
METAMORPHIC ROCKS
MINERALOGY
NORTH AMERICA
NUCLEI
RADIOISOTOPES
ROCKS
STABLE ISOTOPES
TECTONICS
USA
WASHINGTON
YEARS LIVING RADIOISOTOPES