Lithospheric Subduction Beneath the Arakan-Yoma Fold Belt: Quantitative Estimates Using Gravimetric and Seismic Data

A set of consistent geophysical data show the presence of cold material at depth, east of the mountain chain, in the Arakan-Yoma fold belt region. There are intermediate focus earthquakes to a depth of 150 km or so and longitudinal seismic waves are faster under the chain than west of it. The pronounced gravity low, east of the chain, is well explained by cold high density material at depth in the seismic area, compensated by crustal thickening under the mountain chain and a sediment filled depression under the eastern basin. The gravity low flanking other collisional chains might also be due to compensation of cold material at depth rather than the usually invoked flexural effect.