Isopach data show that there is considerable vertical relief along the base of the Miocene stratigraphic sequence, probably due to down-to-the-basin faulting caused by focused deltaic sedimentation and associated crustal flexure.
When viewed in east-west profile, basin shape is more typical of a foreland basin, with sediment thickening eastward toward the Indo-Burman ranges, which reflect an east-west component of convergence.