METER-SCALE CYCLIC SEQUENCES AND COMPOSITE SEA-LEVEL CHANGES ON THE NORTH CHINA PLATFORM DURING MIDDLE CAMBRIAN TIME

The basic stratigraphic units-meter-scale cyclic sequences and their types have been distinguished in the Middle Cambrian oolitic shoal cai-bonate sequences in North China. The meter-scale cyclic sequences are also the basic research units of outcrop sequence stratigraphy. The present paper gives a detailed description of the meter-scale sequence types and features in different systems tracts. The regular stacking patterns of the cyclic sequences in vertical sections which consist of high-order (5th-,4th- and 3rd-order) cyclic sequences are controlled by the composite sea-level changes. The formation of oolitic shoal sequences have experienced several periodic events of drowning,interruption,isostatic accumulation,aggradation and progradation,thus providing a Useful approach to the reconstruction of the basin filling history.