Mangzongrong Fm

The type section is located at Mangzongrong about over 70 km to the northwest of the Zhada County Town in the western part of the Ali Region, Tibet. It was named by Liang Dingyi et al., in 1991.

Clastics. Lower Member of the formation is composed of grey-yellow sandy conglomerate, conglomerate, quartz-sandstone and a part of pebble-bearing slate, with a thickness of 150 m. Middle Member is composed of grey-green sandstone, greywacke, and a small amount of sandy limestone and pebble-bearing slate, with a thickness of 250-350 m; being in a conformable contact with the Lower Member. Upper member is composed of grey-green siltstone and black shale, with a thickness of 15-60 m, and is in a conformable contact with the underlying Middle Member.

Lower Member yields brachiopod fauna represented by Stepanoviella. Middle Member yields a great amount of spiriferoids represented by Neospirifer, Fusispirifer, Spiriferella, and trachyostracous productoids represented by Taeniothaerus, Aulosteges, belonging to the Taeniothaerus assemblage; the corals are represented by the Lytvolasma fauna; and the bivalves are represented by Delponella, which are comparable with the fauna of the Quburiga Fm in the Mount Qomolangma region. Upper Member yields brachiopods represented by Neospirifer, Fusispirifer, Aulosteges, Spiriferella, Mayangella, etc., among which many of them are the predominant kinds of fossils in the Mangzongrong Fm, but no Taeniothaerus has been found and instead there had newly occurred the Lamnimargus himalayaensis, belonging to the Fusispirifer-Lamnimargus assemblage,