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TitleThe consequences of Canadian Cordillera thermal regime in recent tectonics and elevation: a review
AuthorHyndman, R D
SourceCanadian Journal of Earth Sciences vol. 47, no. 5, 2010 p. 621-632,
Alt SeriesEarth Sciences Sector, Contribution Series 20090195
PublisherNRC Research Press
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS92; 93; 94; 95; 103; 104; 105
Lat/Long WENS-141.0000 -114.0000 64.0000 48.0000
Subjectstectonics; tectonic environments; tectonic interpretations; mantle; ground temperatures; temperature; continental crust; crustal thickness; crustal studies; lithosphere; Lithoprobe
Illustrationsschematic sections; plots; location maps; cross-sections
ProgramNational-Scale Geohazard Assessments, Public Safety Geoscience
AbstractThe crust and upper mantle thermal regime of the Canadian Cordillera and its tectonic consequences were an important part of the Cordillera Lithoprobe program and related studies. This article provides a review, first of the thermal constraints, and then of consequences in high surface elevation and current tectonics. Cordillera and adjacent craton temperatures are well constrained by geothermal heat flow, mantle tomography velocities, upper mantle xenoliths, and the effective elastic thickness, Te. Cordillera temperatures are very high and laterally uniform, explained by small scale convection beneath a thin lithosphere, 800 - 900 °C at the Moho, contrasted to 400 - 500 °C for the craton. The high temperatures provide an explanation for why the Cordillera has high elevation in spite of a generally thin crust, ~33 km, in contrast to low elevation and thicker crust, 40 - 45 km, for the craton. The Cordillera is supported ~1600 m by lithosphere thermal expansion. In the Cordillera only the upper crust has significant strength; Te ~ 15 km, in contrast to over 60 km for the craton. The Cordillera is tectonically active because the lithosphere is sufficiently weak to be deformed by plate boundary and gravitational forces; the craton is too strong. The Canadian Cordillera results have led to new understandings of processes in backarcs globally. High backarc temperatures and weak lithospheres explain the tectonic activity over long geological times of mobile belts that make up about 20% of continents. They also have led to a new understanding of collision orogenic heat in terms of incorporation of already hot backarcs.