Derirong Fm

Named by Mu Enzhi in the year of 1973. Yin Jixiang et al. first cited it publicly in 1974. The named section is located on the west hill of the Derirong Bridge.

Synonym: Derirong Gr. In 1965, Gu Qingge named the late Triassic Norian strata with a total thickness of about 1042 m in the southern part of Tingri, Tibet, mainly black-gray shale and sandstone, with a small amount of limestone lenses, as the Qulonggongba Gr. In 1974, Yin Jixiang et al. revised the scope of use of the Qulong Gongba Fm and restricted its time limit to the Early and Middle Norian stage of the Late Triassic. They separated the 150 m quartz sandstone at the top of the original Qulong Gongba Fm as the Derirong Fm, and its time limit is defined as the Late Triassic Norian to Rhaetian. Rao Rongbiao et al. (1987) separated the sandstone stratum about 165 m from the top of the Derirong Fm and named it the “Zamure Fm”. The original meaning of the named Derirong Gr (Derirong Fm) is currently maintained in this Lexicon entry.

Almost all are sandstone, with coarse sandstone intercalated with fine conglomerate layers in the upper part, and only a thin layer of dolomite and sandy limestone in the middle part. It is 591 m thick.

Fossils are scarce, only small individual bivalve fossils Palaeocardita mansuyi, Nucula naperlonga, Myophoricardium tulongense, and Indopecten, Pichleria, Unionites, Myophoria. In addition, there are a small amount of plants, pollen and suspected fossils.

This group is a shallow sea deposit.