Woma Fm
Type Locality and Naming
The type section is located west of the Woma village (E85°18′, N28°46′, see Wang et al., 2006), Gyirong County, Xizang (Tibet) Autonomous Region. Huang and Ji (1979) firstly named this formation. BGMRXTAR (1993) collected this formation, but BGMRXTAR (1997) proposed abandoning the Woma Fm because they considered it can be correlated to part of the Zhada Gr (Zhada Fm), which has type-section much further east (80°E).
Lithology and Thickness
It is divided into three parts: Lower part is formed by yellow and grey siltstones in the upper part, the steel-grey mudstone in the lower part, and the grey siltstones in the bottom part yielding Hipparion Fauna; Middle part consists of grey gravels, yellow sandstones, and grey sandstones, containing laminar sandstones and dark grey sandy mudstones; Upper part is characterized by light yellow mudstones interbedded with a small amount of purple mudstones. This formation contains abundant fossil mammals, mollusks, and sporopollens. Its thickness is about 450 m.
Relationships and Distribution
Lower contact
In the type section, the Woma Fm unconformably contacts with the underlying Upper Jurassic Menkadun Fm.
Upper contact
In the type section, the Woma Fm unconformably contacts with the overlying Lower Pleistocene “Gongba Gravels”.
Regional extent
The formation is restricted in the Gyirong Basin.
GeoJSON
Fossils
(Huang and Ji, 1979) Mammals: Hipparion gyirongensis, Chilotherium xizangensis, Metacervulus capreolinus, Palaeotragus microdon, Gazella gaudryi, Bellatona gyirongensis, Crocuta sp.. Sporopollens: Loropetalum, Quercus, Cedrus, Palmae.
Age
Depositional setting
It is interpreted as a basin environment.
Additional Information