Continental an upwelling plume connecting the hot asthenosphere
Continental lithosphere delamination refers to the detachment and foundering of lithospheric mantle, with or without a certain portion of the lower crust, from the tectonic plate. The concept of lithosphere delamination was introduced by Bird in 1978; 1979, who proposed that the dense lithospheric mantle might peel off from the crust and sink into the underlying asthenosphere, if there is an elongated conduit of an upwelling plume connecting the hot asthenosphere with the base of continental crust.A similar mechanism is the convective removal or thinning of continental lithosphere by the Rayleigh-Taylor gravitational instabilities developed in a thickened lithospheric mantle, (Gorczyk and Vogt, 2013). In both cases the mantle lithosphere is removed and sinks into the asthenosphere because of its negative buoyancy. Delamination is used to explain the thinned or absent mantle lithosphere under orogens where the same processes that thickened the crust should have also thickened the mantle lithosphere. The examples include many orogens in the Alpine-Himalayan collisional belt such as the Tibetan Plateau, the Anatolia, the Apennines and the Alboran Sea, (Timoulalia et al., 2014). Other orogenic belts with proposed delamination include the Cordillera in western regions of both North and South America including the Altiplano-Puna Plateau the Sierra Nevada, the Colorado Plateau, and the Canadian Cordillera (Bao et al., 2015). Delamination has also been proposed for both ancient cratons such as the North China craton and young orogens such as the New Guinea (Cloos et al., 2005). In collisional orogens, lithosphere delamination may occur in either the overriding plate or the subducting plate, or both, with variable spatial patterns. In the Himalayan-Tibetan system, delamination, or convective thinning, is proposed to have occurred under Central Northern TibetanPlateau, where the lithospheric mantle is thought to be abnormally thin or totally missing, (Tilmann et al., 2003). In contrast, delamination could occur in the subducting continental plate, with the mantle lithosphere peeling off from the overlying crust. For example, the Northern Apennines is a fold-and-thrust belt that formed in response to the post collisional retreating of the subducted Adria micro continental lithosphere that is delaminated from the overlying crust (Chiarabba et al., 2014).Both analog and numerical models have been used to study the dynamics of delamination (Francois et al., 2014). In previous numerical studies, lithosphere delamination was usually induced by prescribed weak zones in the initial model configuration (Wang and Currie, 2015). These models focus on the consequences of lithosphere delamination on the topography as well as the mechanical and thermal evolution of the overlying continent. In addition, some models simulate delamination induced by sinking and retreating of high-density subducting lithosphere decoupled from its overlying low-density crust, (Ueda et al., 2012) as shown below. Alternatively, other models simulate various delamination processes induced by eclogitization of the thickened crust under modern or Archean mantle temperature conditions, (Fischer and Gerya, 2016).