Maihanhada Fm
(9), early-Middle Permian
Type Locality and Naming
The type section is located at Maihanhada of the Yibur County, Alashan Left Banner, Inner Mongolia (102°56′E, 41°44′N). It was named by Zheng Zhaochang et al. in 1979.
Lithology and Thickness
Clastics. Composed essentially of clastic rocks, intercalated with bioclastic limestone. Lower part consists of grey conglomerate, variegated pebble-bearing sandstone and calcareous sandstone, intercalated occasionally with thin-bedded limestone, siliceous limestone and bioclastic limestone. Upper part consists of dark-grey greywacke quartz-sandstone and siltstone, yielding brachiopods, corals, trilobites and bivalves. Thickness is about 1240 m. The limestone and conglomerate layers are increasing in amount from W to E, with their thickness getting a bit greater.
Relationships and Distribution
Lower contact
Unconformable contact with the sandstone of the underlying Lower Carboniferous Series; but regionally the next older unit (on Lexicon chart) is the Suhaxibi Fm limestone
Upper contact
Conformable contact with the overlying Aqide Fm
Regional extent
Distributed in the Wuhaxibi-Maihanhada-Wulanbaixing-Hangwula alignment on the northern margin of the Alashan Massif, with its exposures being found also on the southern margin of the Badanjilin Desert.
GeoJSON
Fossils
Brachiopods and coral fossils in the lower part are the Spiriferella-Neospirifer-Kochiproductus-Yakovlevia-Tachylasma assemblage, while those in its upper part yields are the Paramarginifera-Marginifera-Muirwoodia-Verbeekiella assemblage.
Age
Depositional setting
It is interpreted as a shallow-sea facies deposit.
Additional Information