Abstract: The tranditional method of dividing unconformity types is to clasify the unconformity type on the basis of the geometrical relation of two sides of the unconformity plane or the reflection end pattern of the formation, or the unconformity formig mechanism of sedimentation and tectonic, and the mode of seismic reflection end and the morphology of cross section, but the tranditional method cann′t display the relation of the unconformity and oilgas migrationaccumulation. In this paper, on the basis of the tranditional principles on geometrical relation of two sides of the unconformity plane, by the definition of reflection end of sequence identification and the unconformity characteristics in Zhungaer Basin, the unconformity type is at the first time divided into onlap/erosional truncation type, onlap/concordance type, concordance/erosional truncation type, concordance/concordance type. The distribution law of unconformity type is decided by the sea level elevation and denudation. The onlap/erosional truncation type and concordance/erosional truncation type are of all favorableness for the accumulation of oil and gas.

Key words: unconformity type, onlap/erosional truncation type, onlap/concordance type, concordance/erosional truncation type, concordance/concordance type