This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Tectonophysics 501 (2011) 41–51 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Remote sensing revealed drainage anomalies and related tectonics of South India SM. Ramasamy a,⁎, C.J. Kumanan b,c, R. Selvakumar b,c, J. Saravanavel b a Gandhigram Rural University, Gandhigram, Dindigul, Tamil Nadu, 624302, India b Centre for Remote Sensing, School of Geosciences, Bharathidasan University, Tiruchirappalli, Tamil Nadu, 620 023, India c School of Civil Engineering, SASTRA University, Thanjavur, Tamil Nadu, 613401, India article info abstract Article history: Drainages have characteristic pattern and life histories with youthful stage in hilly areas, mature stage in Received 25 December 2008 plains and old stage in the coastal zones. The deviations from their normal life histories, especially aberrations Received in revised form 4 May 2010 in their flow pattern in the form of various drainage anomalies have been inferred to be the indications of Accepted 7 January 2011 dominantly the Eustatic and Isostatic changes. This, especially after the advent of Earth Observing Satellites, Available online 20 January 2011 has attracted the geoscientists from all over the world, for studying such drainage anomalies. In this connection, a study has been undertaken in parts of South India falling south of 14° south latitude to Keywords: fl Lineament comprehensively map some drainage anomalies like de ected drainages, eyed drainages and compressed Drainage anomalies meanders and to evolve the tectonic scenario therefrom. The mapping of such mega drainage anomalies and Active faults the related lineaments/faults from the satellite digital data and the integration of such lineaments/faults with Post collision tectonics the overall lineament map of South India showed that the study area is marked by active N–S block faults and South India NE–SW sinistral and NW–SE dextral strike slip faults. Such an architecture of active tectonic grains indicates that the northerly directed compressive force which has originally drifted the Indian plate towards northerly is still active and deforming the Indian plate. © 2011 Elsevier B.V. All rights reserved. 1. Introduction sea level changes, these drainage anomalies have the credibility of providing information on the flood histories, seismic vulnerability, past Rivers have characteristic pattern and life histories with (1) short climates and anthropogenic phenomenon too (Chitale, 1970; Chen and and straight drainages performing only erosion in the hilly catchments, Stanley, 1995; Lillesand, 1989; Matmon et al., 1999; Miller, 1937; Reid, (2) meandering and sinuous paths doing both erosion and deposition in 1992; Saintot et al., 1999; Smith et al., 1997; Twidale, 2004; Thornbury, the plains and (3) Brownian pattern of movement doing only dumping 1985 and many others). In different parts of the Indian sub continent of sediments and building up of deltas in the coastal zones. Such too, studies have been carried out on the drainage anomalies using characteristic life history of the rivers with youthful stage in the hills, topographic sheets, black and white panchromatic aerial photographs mature stage in the plains and the old stage in the coastal zones in and orbital multimode and multispectral satellite data, to elucidate the general are controlled by the base level of erosion or Mean Sea Level structural fabric, tectonic processes, climatological and other phenom- (Thornbury, 1985). But, the rock types and the geological structures of enon of especially the Quaternary period (Amalkar, 1988; Babu, 1975; the terrain related to palaeo, time transgressive and ongoing tectonisms Bakliwal and Sharma, 1980; Barooah and Bhattacharya, 1989; Mitra et too significantly control the drainage pattern and the related river flow al., 2005; Murty and Mishra, 1981; Narasimhan, 1990; Oldham et al., dynamics in all these three stages. Hence, geoscientists from all over the 1901; Philip et al., 1989; Rajaguru and Kale, 1985; Ramasamy, 1991, world have all along been showing greater interest in understanding the 2006; Ramasamy and Kumanan, 2000; Ramasamy et al., 1987, 1991, drainage architecture in general and their anomalies in particular. That 2006; Singh et al., 1996; Sood et al., 1982; Thirunaranan, 1938; too, after the advent of Earth Observing Satellite technology, mapping of Vaidyanadhan, 1971; Yashpal et al., 1980). drainage pattern and their anomalies like dentritic, semi dentritic, But, despite these, no detailed and comprehensive information is trellis, parallel, annular, radial, deflected, pirated, avulted, eyed, available on the various drainage anomalies and the related tectonics, compressed, preferentially migrated and other drainage anomalies especially for the southern part of the Indian Peninsular, under the have gained greater momentum, since, besides lithology, tectonics and present context of recurring seismicities in the region. Hence, a remote sensing based study has been carried out in the southern part of the Indian Peninsular falling south of 14° south latitude in parts of ⁎ Corresponding author. Tel.: +91 451 2452305 (office), +91 9442105116 (mobile); four states, namely Karnataka, Andhra Pradesh, Kerala and Tamil fax: +91 451 2454535. Nadu for comprehensively mapping the selected major drainage E-mail addresses: [email protected], [email protected] (S.M. Ramasamy), [email protected] (C.J. Kumanan), [email protected] (R. Selvakumar), anomalies and to evolve a holistic picture on tectonics there from [email protected] (J. Saravanavel). (Fig. 1). 0040-1951/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2011.01.011 Author's personal copy 42 S.M. Ramasamy et al. / Tectonophysics 501 (2011) 41–51 Fig. 1. IRS satellite mosaic-study area map. 2. Methodology dors related to such deflected drainages. Similarly, some major drainages flowed as a single channel in the upstream, split up into two In the present study, 21 number of scenes of IRS IB LISS II satellite or more drainages and either finally joined together or showed the data of different paths and dates (February, 1993; April, 1994; March, tendency of rejoining in their downstreams. This assigned conspic- 1995 and May, 1995), with spatial resolution of 36.25 m and spectral uous eyed shapes with entrapped lensoidal/crescent shaped islands resolutions of band1 (0.45–0.52 μm), band2 (0.52–0.59 μm), band3 within them. Such eyed drainages (ED) were mapped as significant (0.62–0.68 μm) and band4 (0.77–0.86 μm) were loaded in the ENVI drainage anomalies, provided these were found either at the crossing image processing software. These independent scenes were georefer- points of some major lineaments or confined within sub parallel enced, false color composites (FCC) were generated by exposing systems of lineaments. Accordingly, these lineaments were also band2 under blue, band3 under green and band4 under red filters and mapped as neo-active tectonic grains related to such eyed drainages. the FCC images were generated independently for 21 scenes and then In the same way, the otherwise normally flowing rivers and major the mosaic was prepared for the study area (Fig. 1). Such digital streams showed anomalous compressed meandering pattern at some mosaic of false color composite data was zoomed up to 1:25,000 scale places in a restricted zone, either at their intersections with some in the computer and scanned in detail for selected, significant and lineaments or confined within sub parallel systems of lineaments. major drainage anomalies viz: deflected drainages, eyed drainages These anomalies were interpreted as compressed meanders (CM) and and compressed meanders. Most of the previous workers from the associated lineaments as neo-active faults related to them. different parts of the world have attributed such drainage anomalies Such prominent and major drainage anomalies say, over 31 to neo-active tectonics. So wherever the major drainages were deflected drainages (DD), 12 eyed drainages (ED) and 20 compressed abruptly deflected by some lineaments, those drainages were marked meanders (CM) and the related neo-active tectonic faults interpreted as deflected drainages (DD). In case, if the original flow of the from different parts of the study area were transferred on to three drainages were already controlled by some lineaments prior to such independent planimetrically controlled GIS overlays using ARCGIS deflections, then both the original controlling lineaments and the software. These three GIS layers were further integrated with the deflecting lineaments were interpreted as neo-active tectonic corri- lineament map of Ramasamy et al. (1999) and the regional probable Author's personal copy S.M. Ramasamy et al. / Tectonophysics 501 (2011) 41–51 43 neo-tectonic picture