摘要
The marine strata in the middle-upper Yangtze region can be divided into 3 types: T, H and TH. Different sequence style has different effect on accumulation.Cap rock deposition and evolution are mainly controlled by the H style. As to muddy cap formations, the cap rocks in the 2nd grade transgression system tracts (TST) of the H style are good in quality. For gypsum cap formations, the cap rocks in good quality mainly locate in the 2nd grade highstand system tracts (HST) of the H style, which has experienced fast transgression and slow regression. It illustrates that the seal capacity of muddy cap rocks in transgression system tracts is better than that in high-stand system tracts.