Initiation of Rayleigh–Taylor instabilities in intra-cratonic settings

A new model of instability development in the lithosphere is presented whereby Rayleigh–Taylor instabilities are initiated as a result of heterogeneities in plastic strength within the lithosphere. Such a model does not depend on large initial variations in the thickness or density of the lithosphere for instabilities to form and hence differs from previously proposed mechanisms. The model is particularly relevant to intra-plate orogenic processes and reproduces many aspects of structural and metamorphic events observed in such settings. In particular the surface topographic evolution of intra-plate settings, especially the development of large intra-cratonic basins, is reproduced. The application to processes operating in an intra-cratonic setting at old cratonic margins is discussed.

► We study development of Rayleigh–Taylor instability at the base of the lithosphere.
► Lateral heterogeneities in the lithosphere lead to initiation of R–T instability.
► A variation in the thickness or density is not essential for instability to develop.
► Delamination of mantle lithosphere leaves significant imprint at the surface.