Stratigraphy of the Lower Devonian sediments in the northwestern Shan Plateau, Myanmar

Abstract

A new lithostratigraphic subdivision for the Lower Devonian sediments of the Pyin Oo Lwin Township, in northwestern Plateau is proposed as the (Pragian-Emsian) which comprises three members, stratigraphically from lower to upper, Khinzo Chaung Limestone, In-ni Chaung Limestone and Doganaing Chaung Orthoquartzite. The type section is designated at the area and the Anisakan-Phaungdaw area, Pyin Oo Lwin Township is considered as a complementary section. The stratigraphy and lithofacies of the formation is studied in detail. Very rich micro- and macrofauna indicate a Lower Devonian (Pragian-Emsian) age and stratigraphically it is closely correlated with those of the same age from the neighbouring regions such as Malaysia, Thailand and China. The as a whole is interpreted as pelagic to shallowing up locally with intertidal channel environment. the largely dolomitic part of the Plateau including the should be called the Shan Dolomite, and that the local calcareous and shaly lenses such as those at Padaukpin and Wetwin should be regarded as members of the regional unit. The names Zebingyi Beds and Maymyo Dolomite Formation are unsatisfactorily defined in terms of modern stratigraphic practice. The lithostratigraphy of the Devonian sediments in the northwestern part of the Plateau is thus in need of revision. In this paper, a new set of lithostratigraphic units is proposed for the Devonian sediments of the area in accordance with the international