There have always been controversial opinions about the age of prolific formations in Ha'ri Depression Well YHC1

Yin'e Basin and the location of unconformity surface between the Cretaceous and Permian.To sort out such controversies

we studied the age of prolific formations in the region and the exact location of the boundary line

based on previous research.The micro-fossils

U-Pb zircon dating of volcanic rocks

mineral compositions and seismic reflection cha-racteristics were analyzed for this purpose.Results show that the sporopollen assemblages of the prolific formations and layers above Well YHC1 can be compared with those of the Lower Cretaceous in Wells Ha1 and Chacan1.The U-Pb zircon ages of the volcanic rocks under the prolific formations are ranging from 131.8Ma to 132.6Ma

indicating that the volca-nic rocks are products of Early Cretaceous eruptions.The mineral compositions of prolific formations are consistent with those of the Lower Cretaceous

but very different from those of the Permian.In addition

both the prolific formations and the volcanic rocks are located within the faulted depression

which is seen from the seismic reflection profile.To sum up

the prolific formations discovered in Ha'ri Depression Well YHC1should fall in the category of the Lower Cretaceous

and the unconformity surface between the Cretaceous and Permian should be located at the bottom of the Bayingebi Formation volcanic rocks.This study is of great significance to hydrocarbon evaluation and exploration in the research zones

and marks brigh prospects for oil/gas exploration in the Lower Cretaceous Yin'e Basin.