Soft-Sediment Deformation as Possible Clue for Sedimentation Rate: A Case Study from Oligocene Andaman Flysch Group, Andaman Islands, India

Two sections of Oligocene Andaman Flysch fan that belong to two different facies associations viz inner fan and mid fan lobe are studied for their soft-sediment deformation (SSD) features Seismic origin is proposed for these features in view of their lateral persistency and stratigraphic selectivity Detailed field measurements of these turbidite sections at Corbyn's Cove, South Andaman (259 m thick) and Kahpur North Andaman (1397 m thick) recorded 28 and 18 nos of SSD layers respectively These layers were compared with historical earthquake records of last 86 years (I e 1914 to 2000) around the studied sections and quantitatively assessed for (l) long-term sedimentation rate and (n) estimation of environment-specific sedimentation rate, if any Active delta shedding from growing orogenic front of Himalayas is believed to be responsible for high sedimentation rate (217 m/lOOOyr at Cove and 58 m/lOOOyr at Kahpur) recorded from this fan system The observed difference in sedimentation rate between the two studied sections is interpreted to be paleogeography driven.