Niru Gr

The type section is located near Lv Village, Niru District, Kangma County, Tibet and named by Tibet Geological Survey Brigade in 1939, and was publicly quoted by Rao et al. (1987). Schematic stratigraphic sections suggests it consists of an upper Zhecun Fm and lower Sunuolin Fm.

Synonym: Nyern Gr, Nieru Fm, Nieru Gr ["Niru Gr" was most common spelling in the Lexicon entry.] Yin et al. (1974) collectively referred to the Triassic stratum in the northern area of Qomolangma (Mount Everest) as the Jilu Group. Wu (1984) believed that there was a significant difference between the southern and northern part in the northern Qomolangma of Triassic stratum, and a set of silty calcareous slate with quartz sandstone and marl, which generally contained pyrite, was above the Permian Baidingpu Fm between Kangma and Jiangzi in the south, and the Triassic strata with a thickness of up to 1,000 meters were collectively referred to as Zhuoga Gr. In 1984, the regional metamorphic strata in the area of Kangma-Saja-Dingri were divided into the Lucun Gr (Lvcun Gr) and the Niru Gr by Tibet Geological Survey Brigade. Rao (1987) officially quoted the two stratum names and affirmed that the upper strata of the Niru Gr belonged to the Upper Triassic Norian.

It is mainly composed of light gray-gray fine sandstone and siltstone interbedded with darker slate, and contains a large number of sandy, siliceous, siderite, phosphatic nodules and quartz sandstone, siltstone and marl. At the standard site, there are relatively more slate and less sandstone in the lower part, and more sandstone and less slate in the middle-upper part. Thickness is 4320 m.

Lower part produces ammonoid: Trachysagenites sp., Arpadites sp., Distichites sp.; Upper part produces bivalves: Indopecten sp., Cassianella gryphacata, Costatoria mansuyi, Pichleria Inaequalis, Pseudolimea planoplicata, Monotis cf. salinaria, Palaeonucula sp., Unionites sp.

Marine facies