NEOTECTONICS OF WESTERN INDIA - EVIDENCE FROM DEFORMED QUATERNARY FLUVIAL SEQUENCES, MAHI RIVER, GUJARAT

A Quaternary fluvial sequence along the Mahi River, Gujarat, western I ndia, shows evidence for a discrete episode of normal faulting and rel ated surface slumping. Four mapped NW-striking faults have throws rang ing from 1 m to over 3 m, and have related growth folds in synchronous sediment units. A slump sheet moved tens of metres northeastward down the 0.7 degrees dip slope of one tilt block during displacement on it s bounding fault. The exposed part of the internally folded sheet is p robably one side of a lobate slump mass, several hundred metres in wid th. Fault activity began after deposition of a lower gravel, which reg ional correlations suggest is about 300 ka old. Faulting ended just be fore deposition of an upper gravel-sand complex dated by luminescence techniques in correlated sections at no younger than about 60 ka. The Mahi River section shows that neotectonic activity in Peninsular India , exemplified by the 1993 Killari (Latur) earthquake, has a mid- to la te Pleistocene component.