Laoran Fm
Type Locality and Naming
Markam (Tibet-Sichuan border). The Laoran Formation was erected by Zhao Xijin in 1979. The section for the designation is in the Laoran Village of Bilonggou of the Markam County, Xizang. It was the lower formation of the Xiangdui Gr (but see that Group entry).
Lithology and Thickness
The Laoran Formation is mainly represented by gray brown and gray purple mudstone interbedded with sandstone and light yellow siltstone with mudstone bands. It is 1004.3 m thick.
Relationships and Distribution
Lower contact
Disconformity. Its base marked by gray brown conglomerate and siltstone is distinguished from the Upper Jurassic Kenzuoga Fm built up by gray green, gray purple and brown red mudstone interbedded with sandstone with small amounts of thin-bedded conglomerate.
Upper contact
Disconformity. Its top is bounded by the base of the Zonggu Fm built up by purple red and brown red silty mudstone with brown and purple red sandstone and mudstone.
Regional extent
The present formation is extensively distributed in Riwoqe-Chag’yab of Qamdo and southward to Markam, with maximum exposed thickness in Markam, Laoran and Xiangdui of Chag’ya. It is the lower formation of the Xiangdui Gr (but see that Group entry).
GeoJSON
Fossils
The formation yields Caenosauria, Coelurosauria, Ankylosauria, Dinosaur, Chelonia and Ceratoius, Microvennator changyabi, Asiatosaurus kwangshiensis, Ceratodus tibetensis, Monkonosaurus lauulacus, and Prodeinodon tibetensis.
Age
Depositional setting
It is of lacustrine deposition.
Additional Information