LAUSR

Abstract This study examines the catchment and source morphodynamics of the Palar River, Southern Peninsular India. Here, we applied a multidisciplinary approach (Remote sensing Techniques, Lineament Analysis, Geochemistry and Ground Penetration Radar) for a better understanding of its evolution during Holocene times. The major lineaments present in the Palar River basin are showing the NE-SW trend. There are five major faults identified in the Palar River basin with a transition zone, where frequent smaller magnitude earthquakes have occurred. The major fault F1 (a strike slip fault) occurs in the upper part of the Palar River following the NE-SW trend. Other major faults present are F2 and F3 with a transition zone where frequent minor and major tremors are documented. Fault F4 traverses in parallel to the Cheyyar River, a rapid change in the river course has resulted due to the movement along these strike-slip faults. F-5 nearer to the east coast indicates a passive tectonic activity regime. The after-effects of tectonic activity in the basin is further implicit from the GPR Profile. The sediments of active Palar River are dominantly litharenite, arkose, wacke; while, the paleochannels are shale in composition. Weathering proxies such as CIA, PIA, elemental ratios along with A–CN–K plot indicate that a post-depositional intense weathering due to climatic variability for all paleochannel sediments. Due to ongoing tectonic activity in the sources region along with subsequent aggradation and degradation in fluvial regimes, the sediments of active Palar River shows low to moderate weathering. Moreover, the geochemical data also reveals that the sediments from the Palar River and paleochannels are predominately from active continental and passive continental margins respectively. Moreover, the major oxide, trace elements and REE elements data indicate that Palar River sediments are from a felsic source while paleochannels are from mafic source. Hence, our study suggests that the catchment area of the Palar River has been shifted to the south during the Holocene period due to tectonic uplift. Subsequently, the sediments of the paleochannels have undergone post-depositional weathering. Due to ongoing tectonic activity and monsoonal changes in the region, enhances rapid erosion in the catchment area results in the deposition of the huge thickness of sediments from the middle to lower reaches of active Palar River.