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Seismic reflection geometry of the Columbia River Fault Zone and East Margin of the Shuswap Metamorphic Complex in the Canadian Cordillera
Author(s) -
Cook Frederick A.
Publication year - 1986
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/tc005i004p00669
Subject(s) - geology , crust , seismic vibrator , seismology , metamorphic rock , foreland basin , thrust fault , tectonics , fault (geology) , wedge (geometry) , normal fault , petrology , paleontology , geometry , mathematics
Vibroseis (CONOCO, Incorporated) seismic reflection data, recorded near the transition between the Cordilleran fold and thrust belt and the east margin of the Shuswap metamorphic complex of the southern Canadian Cordillera, outline an east tapering wedge geometry in the upper crust. The wedge comprises part of the Shuswap metamorphic complex and may be the result of either a foreland‐dipping duplex or tectonic wedging. The geometric wedge separates the overlying miogeoclinal rocks of the Selkirk fan structure from the crystalline basement (?) rocks below, and delineates the eastern limit of the Monashee complex. Brittle motion on the Columbia River fault zone produced an east dipping, listric normal fault which may have offset the upper portion of the Monashee complex. The Columbia River fault zone is imaged over the entire 15 km of the profile and can be traced to a depth of at least 10 km. Reflections from the lower crust are generally subhorizontal and discontinuous, and they may be a manifestation of crustal extension. The crust‐mantle transition is probably represented as reflections with travel times of 11.0–12.0 s.