Abstract

Kinematic simple-shear models have recently been used to provide qualitative explanations for tectonic features in the Basin and Range Province of the southwestern United States and on passive margins. In this paper, a general kinematic simple-shear model is presented. Explicit expressions for the subsidence and stretching factors across a simple-shear zone are derived for two important cases. The first case is one in which simple-shear rifting occurs along a major fault that cuts through the whole lithosphere. In the second case, simple-shear thinning takes place in a brittle zone overlying a regional ductile zone that is undergoing pure-shear thinning. In these cases the subsidence and stretching factors both have characteristic distributions across the stretched region, which can indicate the dominant mode of rifting. It is also shown that simple-shear rifting under the assumption of local isostatic compensation cannot lead to the production of uplifted metamorphic core complexes unless some additional mechanism such as crustal underplating is operating.

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