Author: Timothy Warren GroverPublisher:
ISBN:
Category : Geology
Languages : en
Pages : 286
Book Description
Progressive Metamorphism West of the Condrey Mountain Dome, North-central Klamath Mountains, Northern California
Author: Timothy Warren GroverPublisher:
ISBN:
Category : Geology
Languages : en
Pages : 286
Book Description
Structural, metamorphic and geochronologic constraints on the origin of the Condrey Mountain schist, North Central Klamath Mountains, Northern California
Author: Mark Alan HelperPublisher:
ISBN:
Category : Geological time
Languages : en
Pages : 418
Book Description
The Condrey Mountain Schist (CMS) occupies a window through Late Triassic amphibolite facies melange in the north central Klamath Mountains in northern California and southwest Oregon. The schists owe their present level of exposure to a large structural dome centered on the Condrey Mountain Window. Transitional blueschist-greenschist facies assemblages are widespread in mafic schists in the structurally lowest levels of the window; structurally higher CMS near the window margins contains medium- to high-pressure greenschist facies parageneses. An 40Ar/39Ar crossite age indicates a late Middle Jurassic age of metamorphism. All subunits of the CMS contain evidence of progressive, polyphase deformational and metamorphic histories. The styles and geometries of minor structures in the central part of the window suggest that early folding and transposition was the result of noncoaxial deformation, and that rotational strains were replaced by irrotational flattening strains with time. Rotational strains were accompanied by the development of epidote-crossite assemblages and the growth of deerite in meta-ironstones; irrotational flattening strains were accompanied and followed by the growth of albite, actinolite, spessartine, and the Ba-silicate, cymrite. Pressure-temperature estimates, the relative ages of mineral growth and deformation, and strain geometries are consistent with, but not restricted to, a subduction zone environment. High shear strains may reflect descent and burial, whereas flattening and late, static mineral growth occur during uplift. Pressure-temperature estimates for the overlying CMS greenschists suggest temperatures similar to those in the central part of the window, but at slightly lower pressures. Thrusting of the overlying amphibolites at 150-156 Ma occurred while the amphibolites were above about 500°C. Stretching lineations indicate a movement vector of about N45W. Comparisons of the sequence and timing of metamorphic and structural events, radiometric ages, and movement directions during thrusting indicate the CMS does not represent an inlier of Klamath Western Jurassic Belt flysch but is instead an older, isolated thrust plate. Similarities with the age of metamorphism and plutonism in the overlying amphibolites suggest the two plates may be remnants of the same Middle Jurassic paired metamorphic belt.
Regional Metamorphism in the Condrey Mountain Quadrangle, North-central Klamath Mountains, California
Author: Preston Enslow HotzPublisher:
ISBN:
Category : Geology
Languages : en
Pages : 25
Book Description
Regional Metamorphism in the Condrey Mountain Quadrangle, North-central Klamath Mountains, California
Author: Preston Enslow HotzPublisher:
ISBN:
Category : Geology
Languages : en
Pages : 25
Book Description
Crustal Cross Sections from the Western North American Cordillera and Elsewhere
Author: Robert Bruce MillerPublisher: Geological Society of America
ISBN: 0813724562
Category : Science
Languages : en
Pages : 324
Book Description
"Exposed crustal cross sections provide a unique direct view of continental crust, and are a major source of insights into variations in lithologic and geochemical composition, structural style, metamorphism, plutonism, and rheology with progressive depth through the crust. This volume provides a synthesis of crustal cross sections with a special emphasis on Phanerozoic sections from the western North American Cordillera, supplemented by articles on lower- and mid-crustal sections through Proterozoic crust in North America and Australia, and the classic crustal section of Fiordland, New Zealand. Many of the papers describe multidisciplinary research on crustal sections and include data from various combinations of structural analysis, geochemistry, geothermobarometry, geochronology, geophysics, and other disciplines. The volume also discusses common problems for the interpretation of crustal cross sections, including how sections that expose deep-crustal rocks are eventually exhumed, and leading to the conclusion that there is no simple 'standard model' for continental crust. This volume will be useful to those interested in structural geology, tectonics, geodynamics, regional geology, petrology, geochemistry/isotope geology, and geophysics."--Pub. desc.
Geological Studies in the Klamath Mountains Province, California and Oregon
Author: Arthur W. SnokePublisher: Geological Society of America
ISBN: 0813724104
Category : Science
Languages : en
Pages : 524
Book Description
Accompanying CD-ROM includes additional images and maps.
Metamorphism and Crustal Evolution of the Western United States
Author: Wallace Gary ErnstPublisher:
ISBN:
Category : Science
Languages : en
Pages : 1176
Book Description
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