On the basis of analysing drilling and logging data and geophysical profiles

nappe structures in north Huaiyang tectonic zone have been studied

and the existence

pattern

dynamic background and hydrocarbon significance of Indosinian nappe structures have also been discussed.It is suggested that the unified nappe structural system might be composed of north Huaiyang tectonic zone and Hefei basin in Indosinian period

and the dynamic background might be resulted from the intra-continental subduction of deep crust of North China plate towards the inner orogenic zone.The Indosinian tectonic movement belongs to typical continental structures

and the thrusting nappe structures formed in the Indosinian period might be favorable to hydrocarbon preservation.