The discovery of Early Cretaceous Hauterivian Ammonite Fauna in Bange area, northern Tibet and its constraints on the stratigraphic correlation of the Lower Cretaceous

Recently, ammonites have been discovered in the Bange area of northern Tibet, which of the age is Early Cretaceous Hauterivian.The ammonite assemblages sampled in the Duoni Formation are of good preservation.Two families and one comparative species have been identified, including Polyptychitidae, Neocomitidae, Lyticoceras cf.Stevrecensis.By comparison and analysis with early studies, the ammonites have strong local attribute characteristics.Lyticoceras cf.stevrecensis is the typical species of the Early Hauterivian, which belongs to the subfamily Endemoceratinae, and can be compared with those faunas from the Northern Himalayas, Northern Pakistan and Western Mediterranean(South-East France)around the Tethys realm, even the North-Eastern Peri-Tethys.The discovery of ammonites extends the epoch of Thurmanniceras - Sarasinella to Early Hauterivian.These findings could be important foundations for the stratigraphic correlation study of the Lower Cretaceous, and for re-recognizing the sedimentary tectonic evolution in this area of Cuoqin Basin.