Extensional and Accretionary Tectonics of Western North America: Examples from the Southern Walker Lane and Northwestern Washington State




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In this work, I combine two studies which examine tectonics within the western North American Cordillera. The first study focuses on transtensional tectonics and displacement transfer within the eastern California shear zone and Walker Lane along the western border of the Great Basin. The second study focuses on mélange formation during extension along the accretionary boundary of the North American Cordillera. The studies are thematically linked by the role of fault or plate boundary geometries in the development of complex patterns of displacement transfer and nonplane strain. In the southern Walker Lane, pre-existing faults controlled the development of the Pliocene to Quaternary Palmetto displacement transfer system. The transfer system consists of west-northwest transcurrent and north-northeast extensional faults which accommodate 3 km to 5 km of west-northwest directed extension within the southern Walker Lane east of and adjacent to the Furnace Creek—Fish Lake Valley fault system. In northwestern Washington State, an ophiolitic sedimentary mélange formed within an extensional environment along the accretionary boundary of the North American Cordillera. The mélange and its stratigraphic overlap sequence were deformed during two generations of highly penetrative strain and coeval metamorphism, and subsequently deformed by three generations of folds.



Geology, Structural, North American Cordillera, Melanges (Petrology), Folds (Geology)