Yikenbulage Fm
Type Locality and Naming
Central-Eastern Inner Mongolia. The naming section is located from Huji’ertu to the Yikenbulage Gully in the Qianli Mountains area, Ih Ju League, Inner Mongolia. Named by Wang Banyue et al. in 1981.
Synonym: Yiken Bulag Fm
Lithology and Thickness
Primarily a sequence of brownish red or orange-yellow, medium-fine sandy conglomerate, sandstone, fine sandstone and sandy mudstone, rich in calcareous concretions, with a thickness of 60 m.
Relationships and Distribution
Lower contact
Its base conformably overlies the Early Oligocene Wulanbulag Fm.
Upper contact
Its upper part unconformably underlies the Miocene (Damiao Fm is shown on China Lexicon strat chart)
Regional extent
This formation is distributed in a NNE-SSW zone from the western foot of the northern Qili Mountains in the east to the eastern bank of the Yellow River in the west, and from Qigaigou in the north to the Haorao’er Usu Gully in the south.
GeoJSON
Fossils
This formation also contains abundant mammals, mainly including Amphechinus kansuensis, Sinolagomys kansuensis, Parasminthus pavulus, Tachyoryctoides kokonorensis and Tataromys suni. Among these fossils, only Tachyoryctoides kokonorensis and Tataromys suni are the component elements of the early Miocene Xiejia fauna in the Xining basin, Qinghai, while the greater majority of the forms have been found in the Tapengbulak and Shiqiangzigou faunas in the Danghe River drainage area, Gansu, and almost no fossils of the Wulanbulage Formation underlying this formation or the Hsanda Gol Formation of the People’s Republic of Mongolia have been found. Therefore it is advisable to assign the age of the Yikenbulage Formation to Late Oligocene.
Age
Depositional setting
Additional Information