Composition of the Mianlue suture zone and its relation with the evolution of the old oceanic basin

Abstract: The Mianlue suture zone is a typical ophiolitic-tectonic mélange belt. All the rocks have undergone strong deformation and metamorphism; so the composition of the belt is complex. The dominant tectonic style is marked by an imbricate structure characterized by overlapping of different thrust sheets with a series of north-dipping thrust faults as the framework. Study of its detailed composition and structure suggests that the suture zone is composed of continental-margin sedimentary sequences of different natures formed in different stages of formation and evolution of the oceanic basin, different types of ophiolite and tectonic blocks exposed in different modes during the subduction -collisional orogeny of the oceanic basin. Besides, regional stratigraphic correlation indicates that the formation of the Mianlue oceanic basin is characterized by east-directed "scissors-type" opening and propagation.