Pangyun Fm

Nam Pangyun valley near Bawdwin, Namtu township, Shan State North. Apart from in the type area, the Fm is distributed in the Yadanatheingi–Kyaukme–Longtawknow area, the upper reaches of the Gelaung Chaung area, SE of Wetwin, and in Nankashwe and Nankatha chaungs, east of the Nampeck river (Chaungmagyi Chaung) in the Shan State North. This fm was named the Pangyun Beds by Brown (1918), and termed the Pangyun Fm by Brinckmann & Hinze (1981). [Original Publication: Barber, A. J., Khin Zaw & Crow, M. J. (eds) 2017. Myanmar: Geology, Resources and Tectonics. Geological Society, London, Memoirs, 48, 317-342]

Sandstone. The Pangyun Fm consists of medium- to thick-bedded, red, white, grey and purple sandstones, ripplemarked and cross-bedded quartzite with minor grey banded shale, and brown siltstone and mudstone with lense-like dolomite in places. The Pangyun Fm has two units, and is considered to be contemporary with the Ngwetaung Group of Pyin Oo Lwin township and the Molohein Group of Shan State South. The type section is 200 m thick. Mitchell et al. (1977) described similar rock types from the area south of Bawdwin where the Pangyun Fm consists of a series of clastic deposits, largely purple and white quartzites, with purple conglomerates, green siltstones, cross-bedded quartzites, dolomites and tuffaceous beds, forming distinctive horizons within the Fm. The tuffaceous sediments are the gradational transition between the Bawdwin Volcanic Fm and the Pangyun Fm, and show layering and sometimes cross-laminations but no distinct grading.

Some saukiid trilobites have been found in the upper part of the unit (Hla Wai pers. comm. 1986).

Its depositional environment was the same as the Sibaing Orthoquartzite Fm, representing sedimentation on a shallow-marine, barrier beach.