1994  Kuzina & Lazarev, p.158: Reference section in the area
of Bayan-Sayrin water well. Uppermost part of Tsagan-Khalgi Fm.,
appr. 1670 m lower in section than Lusitanoceras purum.
Interbedded grey and black bituminous limestones, fine-grained
sandstones and greenish-grey and black siltstones, with
brachiopods.