GEOSCAN Search Results: Fastlink


TitleEffects of lithospheric flow on the formation and evolution of a transform margin
AuthorReid, I
SourceEarth and Planetary Science Letters vol. 95, issue 1-2, 1989 p. 38-52
LinksAbstract - Résumé
Alt SeriesGeological Survey of Canada, Contribution Series 47988
NTS1; 10O; 11B; 11G; 11I; 11J; 11O; 11P
Lat/Long WENS -60.0000 -44.0000 48.0000 40.0000
Subjectsstructural geology; tectonics; continental margins; plate margins; faults, transform; crustal studies; continental crust; shearing; oceanic crust; subsidence; rifting; sea floor spreading
Illustrationsschematic diagrams; formulae; graphs; location maps
AbstractA simple model is developed for the processes occurring at a transform continental margin and its predictions are compared with observation. The model emphasises the importance of ductile flow in the lithosphere near the transform. At initiation within continental lithosphere, the upper part of the crust is assumed to be brittle while the lower crust and mantle behave as a Newtonian fluid. Shearing along the transform induces a flow parallel to the direction of motion. With the approach and passage of the abutting spreading centre, flow beneath the continental side of the transform slows and stops. This results in thinning of the lower crust and lithosphere as material is dragged away by the moving oceanic plate. The thinning produces an initial thermal uplift combined with isostatic subsidence, followed by thermal relaxation and subsidence, at and near the margin. The model is developed for uniform viscosity and for viscosity that decays exponentially with depth. The results are found to be generally consistent with the observed structure at transform margins, in particular at the Southwest Newfoundland Transform Margin. It is suggested that the Newfoundland Ridge and analogous features may be formed partly from continental crust emplaced by this mechanism.