Drainage Development in Achankovil Shear Zone, South India

The WNW-ESE trending Achankovil Shear Zone (ASZ) in southern India is a major crustal discontinuity of Proterozoic age which separates Kerala Khondalite Belt (KKB) in the south from the Charnockite massif in the north. The Achankovil river drains this structural valley. Although the river bears imprints of various geologic events, including neotectonic activities, it could maintain a straight course even in the lowland indicating its antecedent nature. The present communication is an attempt to study structural controls on drainage development and evolution within ASZ based mostly on geomorphological evidences and also on some geological indicators.