Evolution of Quaternary landscape as inferred from morphotectonic indices and active tectonics in Son-Narmada-Tapti lineament zone (SONATALZ), Central India

The aim of the study is to investigate the morphotectonic indices and active tectonics and their imprints on Quaternary landscape evolution in Son-Narmada-Tapti lineament zone (SONATALZ) of Central India. The NE and SW part of Gavilgarh/Salbardi fault (G/SF) is considered as one of the deformed zones in Central India which is confirmed by its seismicity at various intensities. The selected morphotectonic indices, which include stream length gradient index (SL) show that the average values of the basins, are 271.22, 192.22 and 371.68, which indicates higher tectonic activity in the Upper Tapi River Basin (UTRB), Maru River Basin (MRB) and Upper Wardha River Basin (UWRB). However, the Chargrah River Basin (CRB) shows a lower SL index value (122.74) and it indicates less tectonic activity. The hypsometric integral (HI) of MRB (0.50) shows a convex curve, young stage and high erosion, whereas, the UTRB (0.43) and UWRB (0.30) basins show concave-convex curve and it indicates mature stage and CRB (0.20) shows concave curve and indicates old stage with high deposition in the basin. The values of valley floor width to valley height ratio (Vf) in UTRB, MRB and UWRB is ranging from 0.16 to 1.42, 0.94 to 22.85 and 2.47 to 38, respectively. The Vf reveals that all three basins have a narrow to broader shaped valley with high erosion rate and high degree of tectonic activity, whereas, the Vf value of the CRB ranges from 9.3 to 23.07 and indicates that the basin is associated with wider U-shaped valley with low erosion rate and less tectonically active. The major lineaments are trending ENE-WSW and NNE-SSW, which imprints the tectonic activity as these are parallel to the SONATA lineament. The field investigation discloses that all the four basins were undergone neotectonic activity in the recent past and need further investigation to determine the intensity of seismicity.