Abstract
Contrary to the classical modes of basin formation based on far-field stresses, here we report on a new mechanism of basin generation by near-field (internal) stresses based on scaled laboratory experiments: basins forming atop a relaxing buckled elastic layer following a far-field compressional event. This investigation builds on the works by Marques and Podladchikov (2009; buckling of elastic layer between viscous and brittle layers) and Marques and Mandal (2016; relaxation of elastic buckles in a viscous medium), but the objective is different: it is basin formation by relaxation of a buckled elastic layer sandwiched between viscous (below) and brittle (above) layers. When the model is horizontally constrained, two types of basins can form by the growth of amplitude and wavelength due to elastic relaxation of the buckles (only vertical motion allowed): narrow basins atop the growing antiforms (outer arc extension), and deep basins in the sinking synforms. If horizontal extension is allowed, then relaxation is not solely by increase in amplitude and wavelength, it is also by horizontal relaxation, i.e. the edges of the elastic layer can move towards the walls, so producing model-scale extension, which widens the basins by extension in the brittle layer. An increase in the thickness of the brittle layer makes it stronger and so hampers basin formation. The new model can be used to explain the formation of post-orogenic basins by near-field stresses, without recourse to the classical mechanism of extension produced by whole plate tensional far-field stresses.
Published Version
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