Preliminary appraisal of deformation structures from Great Nicobar Island, Andaman-Sumatra arc system

The Andaman and Nicobar Group of Islands represent a topographic high of forearc sediments in an actively rising accretionary prism on the Andaman subduction margin. Preliminary observations of deformation structures recorded in tuff are reported from Great Nicobar Island. Active compression led to the formation of meso-scale deformation structures such as a schuppen zone with horse units; sole and roof thrusts; fault breccia zone; high angle reverse faults and pop-up structures. Offset of tuff beds up to a few centimetres are observed across these faults.