Chapter 3 Active and recent tectonics of the Burma Platelet in Myanmar

Abstract

The Burma Platelet covers the western part of Myanmar, lying between the Indian Plate with the attached Bengal Basin in the west and the Sunda Plate in the east. This platelet is also jammed between the volcanic ridges on the Indian Plate in the south and the Shillong continental buttress in the north. The tectonic boundaries of the platelet are the active Sagaing dextral strike-slip fault in the east, and the debatable Bengal Basin subduction zone in the west. This non-rigid sliver plate has accommodated the northwards India/Sunda dextral wrench movement, which has resulted in hyper-oblique convergence since the Early Cenozoic but has also been actively affected by recent lateral buckling and the curvature of the whole platelet. This peculiar structural geometry is discussed here on the basis of geophysical and geological studies conducted during the course of the Geodynamic India–Asia Collision (GIAC) project in Myanmar. The northwestern part of Sundaland is composed mainly of the tectonically active Burma Platelet bordered by the relatively rigid Sunda Plate in the east, the Eurasian Plate to the north, and the presently northwards-drifting Indian Plate with the western margin in the Bengal Basin in the west. The Burma Platelet is the northern extension of a larger microplate, including the Andaman Platelet to the south which is not discussed in this chapter (Fig. 3.1). Fig. 3.1. Extension of the Burma–Andaman–Sumatra microplate (shown in green). The Burma Platelet is the northern part in Myanmar. Active faults are shown in red and inactive faults in purple. The post-Santonian magnetic anomalies and associated transform faults of the Indian and Australian plates are suggested in blue. Left-lateral red arrows along the 90° E Ridge illustrate left-lateral motion between the Indian and Australian plates. India/Eurasia relative motion is shown with a yellow arrow, India/Sunda motion with purple arrows and Australia/Sunda …