Transcurrent movements in the Burma–Andaman Sea region

Abstract

The drag produced by the northward movement of the Indian plate has caused the Indoburman Ranges, an accretionary prism, to decouple from the Burma plate along the Kabaw fault, and the Burma plate itself has decoupled from the Eastern Highlands of Burma along the Sagaing fault. The Indoburman Ranges have probably been dragged north slightly ahead of the Burma plate, although at times the two plates may have locked together to move as one unit. It is suggested that the double arc formed by the Indoburman Ranges and the Andaman-Nicobar-Sumatra islands was formerly one large single arc. Northward translation of this larger single arcuate structure has caused the tail end of the arc, i.e., the Andaman-Nicobar-Sumatra section, to rotate into the Burma plate, causing a bending of the arc to form the present double arc and compression within the Burma plate to form the Pegu Yoma folding. Northward movement of the Burma plate has also resulted in offset by over 400 km of the Irrawaddy River from its former connection through the channel of what is now the Chindwin River.