Ashantou Fm

Central-Eastern Inner Mongolia. The naming section lies at Arshanto in the Sonid Right Banner ~ 32 km southeast of Erenhot, Inner Mongolia, and the reference section is situated in Camp Margetts and the Bayan Ulan area ~40 km southwest of Erenhot. Originally included in the Irdin Manha Formation (=Yierdingmanha). In 1924, the red mudstone and siltstone at the lower part of the section were separated from the upper part and tentatively called the Arshanto Formation, after the name of the Arshanto Obo about 11 km away northeast by C.P. Berkey and F.K. Morris (1924; Bull. Amer. Mus. Nat. Hist., 51, Art.V., 119). [from Wang, Y.Q., et al., 2010. Sci. China Earth Sci, v.53]

Synonym: Arshanto Fm

Predominantly brownish red mudstone and conglomeratic mudstone with grayish green sandy mudstone, mudstone and muddy sandstone, containing gypsum and small numbers of manganese nodules. The lithology is very nonuniform. To the southeast of Erenhot, the sediments are fine; in the vicinity of Huheboerhe coarse clastic rocks increase as a result of certain facies change brought about by different sedimentary environments. Its thickness varies from ~7 to 42 m.

The mammal fauna found in the Arshanto Formation includes at least 11 families and 23 species, of which the perissodactyla group accounts for >50%, containing many Eocene primitive species. Fossils are mainly found in areas such as Camp Margetts, while at the naming locality the species found are rare. The chief members are Tamquammys wilsoni, Archaeoryctes Borealis, Gobiatherium mirificum, Eudinoceras luminus, Schlosseria magister, Lophialetes expeditus and Teilharadia pretiosa. According to Liu Junying (1988), charophytes are mainly represented by an assemblage of dominant Gobichara deserta-Sphaerochara pavula, while the Paleocene-Early Eocene common genera and species such as Nemegtichara and Grovesichara are scarce.

It is suggested to lacustrine deposits.