Abstract:

 Highfrequency cycle of upwardshallowing often develops in lake facies. Underwater discontinuity surface， located at the bottom of cycle， above that paleobathymetry rapidly increases. In continental sequence stratigraphy study， this kind of discontinuity surface is usually directly attributed to ancient lake flooding caused by climate change and underwater nondepositional surface formed by source back. However， this understanding is still difficult to get a satisfactory explanation， and it seems more reasonable if it is classified as results of the basins shortcycle intermittent tectonic subsidence. The research of underwater discontinuity surfaces formation cause in lacustrine highfrequency cycle， not only further explore the basins shortperiod tectonic activity patterns and its influence on lake sedimentation in the highfrequency cycle， but provide research base for better application of Milankovitch cycle theory in lake facies.

Key words: lake facies, highfrequency cycle, underwater discontinuity surface, nondepositional, episodic tectonic subsidence