Middle to late Holocene paleochannels and migration of the Palar River, Tamil Nadu: Implications of neotectonic activity M.R. Resmi a, 1 , Hema Achyuthan a, * , Manoj Kumar Jaiswal b, 2 a Department of Geology, Anna University, Chennai, 600 025, India b Department of Earth Sciences, Indian Institute of Science Education and Research, Kolkata, 741246, India article info Article history: Available online xxx Keywords: Palar River paleochannels Fluvial archives Avulsion Optically stimulated luminescence dating Neotectonic activity NE monsoon abstract Geomorphic, tectonic and sedimentary investigations have been carried out to understand the landscape evolution of the Palar River basin, Southern Peninsular India. For this purpose, satellite data in- terpretations coupled with field investigations, fluvial architecture and optically stimulated lumines- cence (OSL) dating methods were adopted to infer climatic variations and neotectonic deformation that took place during the mid to late Holocene period. Several paleochannels have been identified in the Northern part of the present day Palar River. The distribution pattern of the Palar paleochannels and its present course indicate its migration towards the south, leaving behind the old Palar River streams as paleochannels. Significant changes in the morphological characteristics, channel width and river pattern in the successive paleochannels reveal evidences of channel movement by avulsion largely controlled by reactivation of pre-existing lineaments and intensified NE monsoon. Based on OSL ages, two major phases of migration have been identified that occurred between 4.83 ka to 1.88 ka. First phase occurred between 3.59 ka to 3.26 ka due to intensified monsoon accompanied with small scale neotectonic ac- tivity. The second phase took place between 2.42 ka to 1.88 ka which occurred probably due to the rapid upstream avulsion. This rapid avulsion is due to the close proximity of MPA and the reactivation of the pre-existing lineaments. Moreover, the present Palar River basin exhibits evidences of neotectonic ac- tivity such as soft sediment deformation structures, anomalous drainage deflections and reactivation of lineaments and faults further indicating that the Palar River is still draining a tectonically active region. Thus, neotctonics and fluctuations in the intensity of monsoon are largely responsible for sculpting the present landscape. © 2016 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Tectonism and climate are the major factors affecting any fluvial system (Holbrook and Schumm, 1999; Mather, 2000; Tooth et al., 2002; Vandenberghe, 2002; Bookhagen et al., 2005; Whipple et al., 2013; Kothyari, 2015). The responses of fluvial systems to tectonically active areas include stream beheading and diversion (Wells et al., 1988; Cox, 1994; Bishop, 1995; Gupta, 1997; Clark et al., 2004; Salvany, 2004; Schoenbohm et al., 2004) causing landscape evolution (Seeber and Gornitz, 1983). In response to climatic oscillations and associated environmental changes; the intensity of the participating processes can be delineated using fluvial archives (Gao et al., 2007; Miall, 1985, 1996). However, the drainage basins that typify the contemporary landscape in many areas of the world have developed through significant tectonic (Bishop, 2007; Latrubesse and Rancy, 2000) and paleoenvir- onmental changes through geological time-scale (Paillou et al., 2009). Several case studies, the Mississippi River (Aslan and Autin, 1999; Rittenour et al., 2007), the Nile River (Williams and Williams, 1980; Salama, 1987), Amazon River (Latrubesse and Franzinelli, 2002) and some other African Rivers (Hsü et al., 1973; Rubino et al., 2007) have evolved through; due to remark- able changes in tectonics, climate and even sea level fluctuations since the Cretaceous period but dramatic shifts took place during the Quaternary period. In India, several studies on the late Quaternary fluvial systems is confined to the Northern and Western India with special reference towards channel avulsion, tectonism and paleoclimatic * Corresponding author. þ91-9382849662 (mobile). E-mail addresses: resmiarun.mr@gmail.com (M.R. Resmi), hachyuthan@yahoo. com (H. Achyuthan), mkjosl@gmail.com (M.K. Jaiswal). 1 Mobile No. þ91-9789928735. 2 Mobile No. þ91-9874811800. Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint http://dx.doi.org/10.1016/j.quaint.2016.05.002 1040-6182/© 2016 Elsevier Ltd and INQUA. All rights reserved. Quaternary International xxx (2016) 1e12 Please cite this article in press as: Resmi, M.R., et al., Middle to late Holocene paleochannels and migration of the Palar River, Tamil Nadu: Implications of neotectonic activity, Quaternary International (2016), http://dx.doi.org/10.1016/j.quaint.2016.05.002