Chapter 7 Cretaceous geology of Myanmar and Cenozoic geology in the Central Myanmar Basin

Abstract

This chapter presents an account of the Cretaceous System and its tectonic setting in Myanmar, sedimentary sequences of the Bago Yoma, Central Myanmar and the fluvial architecture of the Irrawaddy Sandstone in the Salin Basin. Myanmar can be divided into four north–south-trending belts – the Shan Plateau, Shan Scarp, Central Myanmar Basin and Indo-Burma Ranges (Figs 7.1a & 7.2a) – which lie on two basement blocks (Stephenson & Marshall 1984; Pivnik et al. 1998; Mitchell et al. 2012; Metcalfe 2013). The Shan Scarp and the Myanmar Central Basin lie on the West Burma Block, whereas the Shan Plateau belongs to the Sibumasu Block. To the west, the Indo-Burma Ranges have been interpreted as an accretionary wedge that resulted from the oblique subduction of the Indian Plate beneath the Burma Plate (Maurin & Rangin 2009). Southwards-prograding deltaic sedimentation with syn-tectonic deep-marine sloping to shallow marine sandstones are recorded in Neogene siliciclastic sequences in the westernmost part of Yakhine (Rakhine) Coastal Ranges (Kyi Khin et al. 2014, 2017). Fig. 7.1. ( a ) Regional tectonic map of Myanmar, showing the Myanmar Central Basins (MCB), Mogok Metamorphic Belt (MMB), Wuntho Massif (WTM), Victoria Massif (VM), Tagaung Myitkyina Belt (TMB), Poppa Volcano (P) and Sagaing Fault (modified after Bertrand & Rangin 2003). HB, Hukaung Basin; CB, Chindwin Basin; MB, Minbu Basin; P, Popa Volcano; BYSB, Bago Yoma-Sittaung Basin; PEB, Pyay Embament Basin; IRB, Irrawaddy Delta Basin. ( b ) Location of the northern Bago Yoma area and surrounding geological units (modified after Kyi Khin 1991). Fig. 7.2. ( a ) Tectonic framework and sub-basins of the Central Basin in Myanmar (after Pivnik et al. 1998). ( b ) General outcrops, lithology, structural pattern and study section of the Taungni-Pingadaw area (modified from Naing Maw Than 1993). The Shan Plateau is characterized by a distinctive Cambrian–Triassic succession, similar …