SHORTENING OF ANALOG MODELS OF THE CONTINENTAL LITHOSPHERE - NEW HYPOTHESIS FOR THE FORMATION OF THE TIBETAN PLATEAU

Initial stages of compression produce periodic buckling of models analogous to a four-layer continental lithosphere. With further shortening, amplification of the buckles occurs by thrust faulting at inflection points in both brittle layers of the upper crust and uppper mantle. The rescaled results suggest that a continental lithosphere under compression will buckle with a first-order wavelength of about 200 km and a second-order wavelength of 20-30 km. Continued shortening results in the amplification of undulations. Troughs sink and become compressional basins while deformation keeps going on major thrusts within the upper mantle, thus giving rise to an irregular topography of the Moho. Fifty percent shortening results in a 60-km-thick continental crust. We argue that this model history may explain the elevation and deep crustal structure of the Tibetan plateau.