Jurassic ammonites of the Wulong area, Tingri County, Tibet

Nicol MORTON, Christian MEISTER, Louis RULLEAU, Xiaoying SHI

Abstract


The Jurassic succession west of Wulong village, Tingri County, southern Tibet, is described. Lithostratigraphical classification uses pre-existing terminology for formations, and an informal subdivision into members is proposed. An important structural dislocation, in the form of a small-scale flower structure, affects the Zhamure Formation straddling the Triassic/Jurassic boundary but does not affect the underlying Derirong Formation (Rhaetian) or the overlying Wulong Formation (Lower Jurassic). No other major structural discontinuities could be recognised. New finds of ammonites in situ include a new genus and species of possible schlotheimiid, Womalongiceras inflatum, with a probable age of Sinemurian or slightly younger. Two separate beds yielded rich assemblages of crushed ammonites identified as Nyalamoceras nyalamensis Chao and Wang (1956) here interpreted as a hammatoceratid. The age of these is reinterpreted as uppermost Aalenian on the basis of an accompanying specimen of ?Pseudolioceras (Tugurites) sp. nov. and poorly preserved ammonites from higher beds identified as graphoceratids (?Graphoceras).

Keywords


ammonites; Jurassic; Tibet; systematic; biostratigraphy

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