Discussions on some basic problems in the research of orogenic belts concerning on flysch and molasse

The pattern and timing of collision are long-term controversies in orogenic research. Flysches and molasses, as one of the most important recorder, have been applied to constrain the collision timing. In this paper, we review research history and their different tectonic meaning in geosyncline-plat-form theory and plate tectonic theory, and then followed by an effort to anatomize their tectonic implications. Flysches in passive margins, active margins or arcs related tectonic settings are deposited before collision, and molasses in peripheral foreland basin after the collision. The youngest flysch could provide information on the maximum collision timing while the oldest molasses in peripheral foreland basin provide information on them-in-collision timing. The transition of sedimentary succession from flysches to molasses indicates that the sedimentation may be continuous during huge tectonic events and thus the collision orogeny is a uniformitive process after the collision event.