Stability of the lithosphere under horizontal compression

B. I. Birger


In a two-layer model of the lithosphere presented in this paper the upper layer (brittle crust) is perfectly plastic and the lower layer is described by a nonlinear rheological model having a memory. This model was recently proposed by the author. The same model is used for the underlying asthenosphere, but with a different value of the rheological parameter. The analysis of stability involves a nontrivial application of the Laplace transformation method. It is shown that the lithosphere is stable under horizontal compression of the order of $10^9$ Pa. The displacements of the free upper surface of the lithosphere decrease with time $t$ like $t^{-1/3}$, whereas this decrease becomes exponential when the proposed rheology is changed to Newtonian. Compression of the lithosphere is a possible mechanism for crustal movements in sedimentary basins. However, the present study shows that this mechanism cannot explain the longest period (about 200 Ma) of the oscillatory crustal movement (tectonic cycles of the first order).

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Computational Seismology, Vol. 4.