关键词: 准噶尔盆地, 下第三系, 古新世, 始新世, 地层剖面, 地层接触关系, 地层划分, 地层年代单位

Abstract: Deposits of Paleocene and Eocene,exposed widely in the north part of Junggar basin,can be subdivided into two formations,the Ugbulak formation and the Huashigou formation.Fossil charophytes,Stephanochara breviovalis,Gobichara deserta and Nemegtichara prima,have been found in the Ugbulak formation.These fossils are common in the late Paleocene in Central Asia.In Sangequan area,the Huashigou formation contains some mammal fossils:Hyopsodus huashigouensis,cf.Mesonyx uqbulakensis,cf.Metahapalodectes sp.,Pantolambdodon sp.,Metacoryphodon sp.,Uintatherium cf.insperatus,Schlosseria magister,and Breviodon minutus.The mammal assemblage shows that age of the fossiliferous beds are equivalent to Arshantan(M.Eocene).In Jimunai-Buerjing area a few teeth of Hyaenodon and anthracotheriid,which are thought to appear in late Eocene,are found from the same formation.Therefore,the deposition of the formation may be extended to a later period.