Native terranes: examples from the Cordillera

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6863499

Gray, G G

The suspect terrane concept has provided a new working hypothesis which has been invaluable for interpreting complex continental margin areas. This concept is restrictive, however, because it allows for only exotic or suspect terrane origins, while there is a growing body of evidence that many terranes have developed in situ. The authors propose that such in situ units be called native terranes. Stratigraphic, metamorphic, and disrupted terranes in the Klamath Mountains of northern California and southern Oregon are examples of native terranes. A variety of oceanic crust and Tethyan seamount-derived units were accreted in a Late Triassic subduction zone in this area. Each of these terranes is highly disrupted, and contains blocks derived from North American units to the east. The incorporation of North American blocks into these terranes, coupled with paleomagnetic data and intrusive relationships, indicates that these exotic block-bearing disrupted terranes developed in their present position adjacent to North America and are therefore native. A coeval blueschist terrane developed inboard of these melanges and is also considered native. A coherent Middle Jurassic arc (.) sequence built upon this melange basement constitutes a native stratigraphic terrane. The present melange basement constitutes a native stratigraphic terrane. The present boundaries of these terranes are typically thrust faults and normal faults which postdate accretion. Similar mixtures of North American and exotic blocks have been noted in coeval accretionary belts in the Sierra Nevada foothills, east-central Oregon and eastern British Columbia.

• Research Organization: Univ. of Texas, Austin (USA)
• OSTI ID: 6863499
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
580201* -- Geophysics-- Seismology & Tectonics-- (1980-1989)
BRITISH COLUMBIA
CALIFORNIA
CANADA
CONTINENTAL MARGIN
EARTH CRUST
FEDERAL REGION IX
FEDERAL REGION X
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
LITHOLOGY
MAGNETISM
METAMORPHISM
NORTH AMERICA
OCEANIC CRUST
OREGON
PALEOMAGNETISM
PLATE TECTONICS
STRATIGRAPHY
SUBDUCTION ZONES
TECTONICS
USA