Abstract The geology of the petroleum-bearing parts of Myanmar (essentially the western part of the country) is dominated by the oblique collision between the fixed Sunda Plate in the east (itself a mosaic of Gondwana-derived blocks, and since the Mesozoic a part of the much larger Asian or Eurasian Plate; Fig. 2.1) and the north-moving India Plate (e.g. Curray et al. 1979; Mitchell 1993; Curray 2005; Socquet et al. 2006; Steckler et al. 2008; Hall 2012; Rangin et al. 2013). Before considering the origin of the component parts of Myanmar it is necessary to identify the main structural units that now comprise the western part of the country. Figure 2.1 shows the importance of the Sagaing Fault and its possible offshore continuation in separating the Burma Platelet from the Sunda Plate to its east. Here we follow the terminology of Rangin et al. (2013) in choosing to call this the Burma Platelet, although earlier it was called the Burma Plate by Curray et al. (1979), the Indo-Burma-Andaman Block by Acharyya (1998) and the West Burma Plate by others (e.g. Hall 2012; Metcalfe 2013). The platelet is complex and is discussed further below, but one of its obvious features is the discontinuous belt of dormant volcanoes and granitoid intrusions running down the Central Burma Depression and dividing that major downwarp into forearc and back-arc tectonic domains (Wang et al. 2014). The cones of Mount Popa and Mount Taungthonlon (Fig. 2.1) are among Myanmar’s highest peaks, and the volcanic arc reappears in the Indian sector of the Andaman Sea as the active strato-valcanoes of Narcondam and Barren islands (Bandopadhya et al. 2014) before joining the volcanic arc of Sumatra.