Abstract

Mass-transport complexes (MTCs) form a significant component of the stratigraphic record in ancient and modern deepwater basins worldwide. One such basin, is the forearc basin of Andaman, situated along the obliquely converging boundary of the Indian plate and Burmese plate and is characterized by active tectonics and possible migration and sequestration of hydrocarbons. Major structural elements found in the forearc basin include transpressional faults (i.e., Diligient Fault and Eastern Margin fault) and anticlinal structures (result of basin inversion) overlain by extrusive sea - floor mud volcanoes. The interpretation of a 3D seismic survey in the study area enabled mapping of several erosional surfaces that form the boundaries of multiple mass transport complexes. The data show multiple episodes of MTC developments, which are characterized by chaotic, mounded seismic facies and fan like geometry. Their extent and thickness is strongly influenced by the sea floor topography. Individual mass transport deposits (MTDs) show long runout distances from the source area. The depositional architecture identified within these units includes i) large-magnitude lateral erosional edges, ii) linear basal scours and iii) side-wall failures. In the study area of Andaman Forearc, two major MTCs are observed which are separated by finer clastics, deposited in a shallow marine environment and are classified as