Dobgyu Fm

Himalayan North Belt. The Dobgyu Formation was erected by Wang Naiwen, Liu Guifang and Chen Guoming in 1983. The section for the designation is in the Kadong Village- Duoque- Zuomadingla of the Duoque District of the Nagarze County, Xizang (90°07′E; 28°08′N). The reference section is at Gongboxue (Longbuxue)-Shelangreshan- Bajiutang of the Nagarze County, Xizang (91°00′E; 28°06′N).

The Dobgyu Formation is divided into two members. Lower member is represented by gray yellow siliceous shale interbedded with calcareous shale, occasionally with marl and gray clayey limestone nodules, with a thickness of 400 m and with abundant ammonite faunas. Upper member is built up by dark gray calcareous shale and marl interbedded with shale, intercalated with gray green siliceous shale, gray compact limestone and marl lenses or partings, bearing abundant pyrite nodules. The formation is 300 m thick and yields ammonites. In the basal part of the formation, siliceous shale is interbedded with calcareous shale, which lies conformably on the underlying Zawangzi Fm, with a thickness of 700 m.

In the Duoque area, the formation bears ammonites such as Lyelliceras cf. lyelli in the upper member, Lyelliceras pseudolyelli, Leymeriella sp., Hamites (H.) sp., Pseudohelicoceras sp., Oxytropidoceras multifidum, O. aff. crassicostatum, Venezoliceras aff. venezolanum, V. aff. chichuahuense, Moisisoviczia ventanillensis, M. aff. dellaruei, Desmoceras (D.) sp., etc. in the lower member.