THE JURASSIC CRETACEOUS IN THE YA’AN- BAOXING AREA, SICHUAN

On the basis of the data of 1∶50 000 regional geological surveys, the Jurassic Cretaceous strata in the Ya’an Baoxing area, Sichuan province, are divided in ascending order into the Baitianba, Qianfoya, Shaximiao, Suining, Lianhuakou, Tianmashan, Jiaguan and Guankou Formations. This paper describes the sequences of strata and rock associations of the stratatype section and discusses the biostratigraphic and chronostratigraphic problems. The author has analyzed the Jurassic Cretaceous depositional environments and preliminarily recognized the fluvial, lacustrine and alluvial fan facies.