Chapter 15 Sedimentary facies and biotic associations in the Permian–Triassic limestones on the Shan Plateau, Myanmar

Abstract

The Plateau Limestone, a thick carbonate rock unit representing Permian–Triassic stratigraphy in Myanmar, is extensively developed on the Shan Plateau of eastern Myanmar. The name was proposed first by La Touche (1913) for thick dolomites and crystalline limestones of Devonian and Permo-Carboniferous age, widespread throughout the Shan Plateau. This limestone unit was subsequently informally designated the Lower Plateau Limestone, referring to the shattered dolomite of Devonian age, and the Upper Plateau Limestone for the Permo-Carboniferous limestones (Brown & Sondhi 1933). The lithostratigraphy and palaeontology of this unit have been investigated to some extent by previous workers, particularly Brown & Sondhi (1933), Pascoe (1959), Brunnschweiler (1970), Gramann et al. (1972), Amos (1975), Garson et al. (1976), Bronnimann et al. (1978), UN Team (1979), Whittaker et al. (1979), Zaw Win (1991, 2004, 2008), Thura Oo et al. (2002), Zaw Win & Kyi Kyi Shwe (2005) and Zaw Win et al. (2011). Amos (1975) gave a comprehensive account of previous work and proposed a formal lithostratigraphic classification scheme for this carbonate unit. His classification was subsequently refined by Garson et al. (1976) and the UN Team (1979). Limestones of Devonian age occur as limited outcrops in the northern part of the Shan Plateau only, and its stratigraphic relationship to the Plateau Limestone has not yet been resolved. Up to the present, there has been no record of palaeontologically well-documented Carboniferous limestone on the Shan Plateau itself or in adjoining areas, but the Carboniferous is now documented by fossil evidence. The Plateau Limestone, formerly designated ‘Permo-Carboniferous’, is now known to be mainly of Permian age and in places ranges up into the Middle Triassic. On the other hand, little research has been carried out on the temporal and spatial patterns …