The Middle-Upper Permian Gufeng Formation and Dalong Formation are the important target horizons for the source rock exploration in South China. However

due to the obvious lithologic changes in both spatial and temporal distributions

there is still great controversy in the division and comparison of the regional stratigraphy

which restricts the exploration and potential evaluation of oil and gas resources. Thus here we analyzed six typical field outcrops of the Gufeng and Dalong Formations in the Lower Yangtze regi

on and summarized their lithostratigraphic characteristics. By the regional comparison

we further analyzed their vertical and lateral lithofacies distribution. Combined with the geochemical parameters such as total organic carbon（

TOC

） content

the exploration potential of shale oil and gas is discussed. The results show that the lithological thickness of the Gufeng Formation in the Lower Yangtze region varies greatly

showing the characteristics of alternating thick and thin

and its deposition center is generally located in the areas of Fanchang-Wuhu and Jurong-Lishui. The Gufeng Formation can be basically divided into three members

among which the middle member with interbedded chert and siliceous mudstone is regionally stable and thick. The thickness of the Dalong Formation does not change much regionally

but it is affected by the paleogeographical setting. The lithological differentiation of the Dalong Formation is obvious in the region

and its chert and siliceous mudstone is mainly developed in the southern Anhui area

while in the northern Jiangsu area

it changes to shale. Based on the previous studies

it is suggested that the Gufeng and Dalong Formations of the Lower Yangtze region have high

TOC

contents

good organic matter types

and their maturity is generally within the gas generation range

indicating that they have great shale gas potential. The vertical distribution characteristics of the

TOC

in the Gufeng and Dalong Formations indicate that their middle-upper member is a more favorable horizon for shale gas exploration. Regionally

the Wuwei Basin

Jurong-Nanling Basin

Changzhou-Xuanguang Basin and Wuxi-Suzhou area are the relatively favorable areas for shale gas exploration; the Xuanguang-Meishan Basin and the Jurong Danyang-Huangqiao-Taizhou area have shale oil exploration prospects due to their low maturity.