Bulong Fm
Type Locality and Naming
The type section is located near the Bulong village (N31°52′, E92°59′), Biru County, northern Xizang (Tibet) Autonomous Region. (BGMRXTAR, 1997). Huang and Ji (1979) firstly named this formation.
BGMRXTAR (1997) proposed abandoning the Bulong Fm because they considered that the Bulong Fm can be correlated to the Tuolin Fm in Zhada Basin. [NOTE: Seems that the China Lexicon and T. Deng et al. (2019) simplify by placing Bulong Fm in same column as the Zhada Fm (and Woma Fm), even though type sections are far apart.] Zheng et al. (1999) still collected this formation.
Lithology and Thickness
It is a series of motley gravels interbedded with mudstones. Its upper part is characterized by grey mudstones and medium to fine sandstones; the middle part consists of black mudstones interbedded with greyish-black muddy shales; its lower part is formed by brown ferric cementing gravels or ferricrete. It upper part contains fossil mammals, plants, gastropods, and sporopollens. Its thickness is in about 40 m.
Relationships and Distribution
Lower contact
In the type section, the Bulong Fm unconformably contacts with the underlying Upper Jurassic to Lower Cretaceous Qusongbo Gr (BGMRXTAR, 1993).
Upper contact
In the type section, the Bulong Fm is unconformably overlain by Quaternary loose sands and gravels.
Regional extent
The formation is restricted in the Bulong Basin.
GeoJSON
Fossils
Mammals: Brachyrhizomys nagquensis, Crocuta gigantean var. xizangensis, Metailurus sp., Felis sp., Chilotherium tanggulaensis, Samotherium sp., Gazella sp., Hipparion xizangensis. (Huang and Ji, 1979). Sporopollens: Abies, Picea, Pinus, Cedrus, Tsuga, Pinaceae, Polocarpus, Cuprassaceae, Carya, Carpinus, Betula, Ostrya, Quercus, Ulmus, Celtis, Acer, Tilia, Plmae, Salina, Ephedra, Chenopodiaceae, Artemisia, Liliaceae, Cyperaceae, Polypodium, Adantum, Pteris. (BGMRXTAR, 1993)
Age
Depositional setting
It is interpreted as a small intermontane basin environment.
Additional Information