Geomorphic indicators of active tectonics in the Karjan river basin, Lower Narmada Valley, western India

The Karjan basin is one of the largest tributary basins of the Lower Narmada Valley. A major part of the basin comprises southward dipping basaltic flows of the Deccan Volcanic Group (DVG) delimited to the north by the Narmada-Son Fault. The lineaments indicate a strong control of the ENE-WSW and NNW-SSE trends on the geomorphology and drainage architecture. The ENE-WSW trending ridges with southern slopes and north facing escarpments including the Narmada-Son Fault (NSF) and ENE-WSW trending narrow intramontane valleys evidence the dominant control of ENE-WSW trend. Three tilt blocks have been delineated within a major tilt block formed due to differential uplifts along the NSF and two other sympathetic faults. A gradual decrease in the ruggedness of the topography towards south, preferential locations of river pondings, gorges and increased fluvial incision suggest continued southward tilting of the fault blocks due to differential uplift along ENE-WSW trending faults. The alluvial zone to the north of the Narmada-Son Fault is made up of Late Pleistocene to Holocene sediments and indicates two phases of river incision in the Karjan river basin, which are attributed to uplifts during Early and Late Holocene. Morphometric analyses of parameters sensitive to tectonics substantiate the field observations on active tectonics. The field evidence from the upland and alluvial zone and the morphometric analyses point to differential uplift of the Karjan basin along ENE-WSW trending faults during Holocene.