Xiling depression is a basin formed at the front of plates in Variscian fold belt during the Meso-Cenozoic. It is characterized by relatively higher separation

long-narrow form

well developed fractures

frequent sedimentary gaps and magmatic activities

etc. The depression area is more than 70 thousand square killometers

the depression depth is about 1500—3500m.Two sets of target beds are developed:the Upper Jurassic Badalahu Formation and Lower Cretaceous Bayanhua Formation. The distribution of the former is smaller

but with better parent materials which have reached good maturity and given rise to more oil and gas shows as well as good reservoir property. The latter is distributed in a much wider extent

but its parent materials are more or less worse and has lower maturity. Only local places have good conditions. It is revealed by seismic exploration and drilling that

in present areas studied

oil traps are varied

and oil sands with total thickness of 70m have been found in the Badalahu Formation. Some of medium to small-sized oilfields are expected to be discovered.