Tabyin Fm

Chindwin Basin, the name Tabyin Clays is taken from the village of Tabyin, a village about 23 kilometers due west of Pauk. Minbu Sub-basin. [Original Publication: Barber, A. J., Khin Zaw & Crow, M. J. (eds) 2017. Myanmar: Geology, Resources and Tectonics. Geological Society, London, Memoirs, 48, 219–260]

Synonym: Tabyin Clays

[Figure: Map showing location of sub-basins of the Central Myanmar Basin (after Myint Thein and M. Maung 2017)]

Claystone. Mainly blue-grey, soft, nodular shale beds. Generally, the Fm is a clay with sandstone reinforcements, showing a more arenaceous character as it is traced northwards. The Tabyin Clays are characterized by a group of greenish yellow shales, which locally include thin impure coal seams. Further north in the Upper Chindwin District, the Ngapum alternations, of greyish green mudstones and grey sandstones with some calcite and lignite are probably equivalent. Thickness is 3200 m. In Minbu-Salin Basin and Pyay Embayment, clayey sandstone. The Tabyin Fm is composed of shale beds, interbedded with argillaceous sandstones. Shales are dark grey to grey, thinly laminated, micaceous, fairly carbonaceous and fossiliferous in places. Sandstones are grey, moderately hard, thinly bedded, carbonaceous and argillaceous, interbedded with fossil-bearing calcareous lenses.

[Figure: Stratigraphic succession of the Chindwin Basin (after Than Htut, 2017)]

In Minbu-Salin Basin and Pyay Embayment, Nummulite sacutus.

Deposited under pro-delta conditions in Chindwin Basin, deposited in a nearshore to shallow-marine environment in Minbu-Salin Basin and Pyay Embayment.