Stratigraphy of Mesozoic and Cenozoic intracontinental orogenic zones: an example from the Yanliao orogenic zone

An intracontinental orogenic zone is referred to as a sialic orogenic zone that was grounded against the cratonic basement, and thus differentiated from periplate or interplate orogenic zones. The orogenic zone formed in the interior of an old hard lithospheric plate is generally characterized by unusual structural deformation (thrust and fold development), magmatism (magmatic intrusion and volcanic eruption) and metamorphism (synorogenic metamorphism). The Mesozoic and Cenozoic intracontinental orogenic zones in the Yanliao region may, by and large, go through three stages of evolution:(1) the pre-orogenic stage, when the Precambrian cratonic basement and pre-Mesozoic and pre-Cenozoic stable cratonic cover were developed; (2) main orogenic stage, when the intraplate orogenic zones came into being in some zones in which the cratonic basement and cover were developed during the Mesozoic and Cenozoic, and (3) re-orogenic stage, when the orogenesis was regenerated after a long period of stable equilibrium. Correspondingly three types of tectonic and stratigraphic units are delineated.