The Paleozoic in Jiyang depression can be divided into three super-sequences and 14 third-order sequences by using sequence stratigraphy theory and cycle analysis of datum level

combining with drilling

seismic and logging methods. The super-sequences are the Mantou formation-Liangjiashan formation (A)

the Xiamajiagou formation-Badou formation (B) and the Benxi formation-Shiqianfeng formation (C). According to calibration of sequences in regional seismic profiles

an isochronic framework of the Paleozoic sequence stratigraphy in Jiyang depression is established through tracing and interpreting the four super-sequence boundaries. The three super-sequences are clear in logging-constrained inverse profiles

showing low

high and low impedances from bottom to top

respectively. The main identification marks of sequence boundaries are unconformable surfaces

scouring surfaces of rivers

surfaces showing abrupt changes of litho-electric properties and color

of which unconformable surfaces are super-sequence boundaries

while others are boundaries of third-order sequences. Standards for dividing seismic sequences are defined and a sedimentation model is developed for the Paleozoic sequence stratigraphy in Jiyang depression