文摘
Continental extension may occur in two main different modes, narrow and wide rifting, which mainly differ in the width of the deformed region. A third mechanism, the core complex, has been considered either a distinct mode of extension or a local anomaly within wide rifts. In terms of causative processes, continental rifting may be explained by both active or passive mechanisms, which also differ in the volume of magmatic products and in the rheological properties and stratification of the extending lithosphere. Both numerical and analogue models have investigated the main parameters controlling the extension of a rheologically layered lithosphere. In particular, analogue models have highlighted that the style of deformation is mainly controlled by the competition between the total resistance of the lithosphere and the gravitational forces; this competition, in turn, is mainly controlled by boundary conditions, such as the applied strain rate and the rheological characteristics of the extending lithosphere.
