Western Old Woman Mountains shear zone: Evidence for late ductile extension in the Cordilleran orogenic belt
Journal Article
·
· Geology; (United States)
- Vanderbilt Univ., Nashville, TN (United States)
- State Univ. of New York, Albany (United States)
Rocks within the 1-km-thick Western Old Woman Mountains shear zone (WSZ) contain ductilely deformed quartz and ductilely and brittlely deformed feldspars, indicating greenschist to lower amphibolite facies mylonitization. Foliation measured in 73 Ma mid-crustal granitoids within the zone generally dips west-southwest, and sense-of-shear indicators demonstrate top-to-the-west sense of movement parallel to gently southwest plunging lineation. The tip of the shear zone is not exposed, but 10 km to the west unmetamorphosed Late Cretaceous-age upper crust is present. The WSZ is thus most simply interpreted as a normal-sense low-angle shear zone. Timing of deformation is constrained to the interval 73 to ca. 65 Ma by the age of deformed granitoids and {sup 40}Ar/{sup 39}Ar chronology. This interval coincides with a period of rapid cooling of rocks now exposed in the Old Woman Mountains that probably resulted from 4 to 8 km of unroofing. The authors suggest that movement along the WSZ is responsible for at least some of this unroofing. The proposed history involves tectonic denudation along a low-angle ductile shear zone and is similar to that demonstrated for Tertiary Cordilleran metamorphic core complexes.
- OSTI ID:
- 5942150
- Journal Information:
- Geology; (United States), Journal Name: Geology; (United States) Vol. 19:9; ISSN GLGYB; ISSN 0091-7613
- Country of Publication:
- United States
- Language:
- English
Similar Records
{sup 40}Ar/{sup 39}Ar thermochronology and thermobarometry of metamorphism, plutonism, and tectonic denudation in the Old Woman Mountains area, California
Mesozoic and Cenozoic thermal history of the eastern Mojave Desert, California and western Arizona, with emphasis on the Old Woman Mountains area and the Chemehuevi metamorphic core complex
The sup 40 Ar/ sup 39 Ar thermochronology of the eastern Mojave Desert, California, and adjacent western Arizona with implications for the evolution of metamorphic core complexes
Journal Article
·
Fri Jan 31 23:00:00 EST 1992
· Geological Society of America, Bulletin
·
OSTI ID:543081
Mesozoic and Cenozoic thermal history of the eastern Mojave Desert, California and western Arizona, with emphasis on the Old Woman Mountains area and the Chemehuevi metamorphic core complex
Thesis/Dissertation
·
Sat Dec 31 23:00:00 EST 1988
·
OSTI ID:5263558
The sup 40 Ar/ sup 39 Ar thermochronology of the eastern Mojave Desert, California, and adjacent western Arizona with implications for the evolution of metamorphic core complexes
Journal Article
·
Fri Nov 09 23:00:00 EST 1990
· Journal of Geophysical Research; (United States)
·
OSTI ID:5262925
Related Subjects
58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ARGON 39
ARGON 40
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALIFORNIA
COMPACTING
CONTINENTAL CRUST
CRETACEOUS PERIOD
DEFORMATION
DEVELOPED COUNTRIES
EARTH CRUST
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGY
ISOTOPE DATING
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MESOZOIC ERA
METAMORPHIC ROCKS
MOUNTAINS
NORTH AMERICA
NUCLEI
RADIOISOTOPES
RESERVOIR ROCK
ROCKS
SHEAR
STABLE ISOTOPES
TECTONICS
USA
YEARS LIVING RADIOISOTOPES
580000* -- Geosciences
AGE ESTIMATION
ARGON 39
ARGON 40
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALIFORNIA
COMPACTING
CONTINENTAL CRUST
CRETACEOUS PERIOD
DEFORMATION
DEVELOPED COUNTRIES
EARTH CRUST
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGY
ISOTOPE DATING
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MESOZOIC ERA
METAMORPHIC ROCKS
MOUNTAINS
NORTH AMERICA
NUCLEI
RADIOISOTOPES
RESERVOIR ROCK
ROCKS
SHEAR
STABLE ISOTOPES
TECTONICS
USA
YEARS LIVING RADIOISOTOPES