Abstract: The Lower Paleozoic in Jiyang depression could be divided into two supper sequences (Sequence A and Sequence B) or two big datum-level cycles which were Cambrian Mantou group to Ordovician Yeli-Liangjiashang group and Ordovician Lower Majiagou group to Badou group. They correspond to eight sequences that are made up of transgressive system tract and high system tract for each one. The assembled relations among source-reservoir-cap rocks show that the source rocks in Sequence A are not developed as a whole, but the dolomite of its Liangjiashan group is an important buried hill reservoir rock. The multi-stage karstifications are found in the weathering crust in top of Sequence B, with superior reservoir condition, and can be as major reservoir rock in the buried hill reservoir. The argillaceous limestone and thick limestone of Majiagou group should be as potential source rocks for the reason of higher content of organic matter. The thick dark mudstone beneath the Upper Paleozoic acts as a preferable regional cap formation, forming a good sourcereservoir-cap rock assemblage along with underlying Cambrian and Ordovician systems. These are the favorable conditions for shaping original oil-gas reservoirs in this area.

Key words: Jiyang depression, Lower Paleozoic, sequence stratigraphy, petroleum exploration, hydrocarbon prospect