10 Remote Sensing Revealed Drainage Anomalies and Related Tectonics of South India
Abstract
Drainages have characteristic pattern and life histories with youthful stage in hilly areas, mature stage in plains and old stage in the coastal zones. The deviations from their normal life histories, especially aberrations in their flow pattern in the form of various drainage anomalies have been inferred to be the indications of dominantly the Eustatic and Isostatic changes. This, especially after the advent of Earth Observing Satellites, 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 comprehensively map some drainage anomalies like deflected drainages, eyed drainages and compressed meanders and to evolve the tectonic scenario therefrom. The mapping of such mega drainage anomalies and the related lineaments/faults from the satellite digital data and the integration of such lineaments/faults with the overall lineament map of South India showed that the study area is marked by active N–S block faults and 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.
Introduction
Rivers have characteristic pattern and life histories with (1) short and straight drainages performing only erosion in the hilly catchments, (2) meandering and sinuous paths doing both erosion and deposition in the plains and (3) Brownian pattern of movement doing only dumping of sediments and building up of deltas in the coastal zones. Such characteristic life history of the rivers with youthful stage in the hills, mature stage in the plains and the old stage in the coastal zones in general are controlled by the base level of erosion or Mean Sea Level (Thornbury, 1985). But, the rock types and the geological structures of the terrain related to palaeo, time transgressive and ongoing tectonism too significantly control the drainage pattern and the related river flow dynamics in all these three stages. Hence, geoscientists from all over the world have all along been showing greater interest in understanding the drainage architecture in general and their anomalies in particular. That too, after the advent of Earth Observing Satellite technology, mapping of drainage pattern and their anomalies like dentritic, semi dentritic, trellis, parallel, annular, radial, deflected, pirated, avulted, eyed, compressed, preferentially migrated and other drainage anomalies have gained greater momentum, since, besides lithology, tectonics and sea level changes, these drainage anomalies have the credibility of providing information on the flood histories, seismic vulnerability, past climates and anthropogenic phenomenon too (Chitale, 1970; Chen and Stanley, 1995; Lillesand, 1989; Matmon et al., 1999; Miller, 1937; Reid, 1992; Saintot et al., 1999; Smith et al., 1997; Twidale, 2004; Thornbury, 1985 and many others). In different parts of the Indian sub-continent too, studies have been carried out on the drainage anomalies using topographic sheets, black and white panchromatic aerial photographs and orbital multimode and multispectral satellite data, to elucidate the structural fabric, tectonic processes, climatological and other phenomenon of especially the Quaternary period (Amalkar, 1988; Babu, 1975; Bakliwal and Sharma, 1980; Barooah and Bhattacharya, 1989; Mitra et al., 2005; Murty and Mishra, 1981; Narasimhan, 1990; Oldham et al., 1901; Philip et al., 1989; Rajaguru and Kale, 1985; Ramasamy, 1991, 2006; Ramasamy and Kumanan, 2000; Ramasamy et al., 1987, 1991, 2006; Singh et al., 1996; Sood et al., 1982; Thirunaranan, 1938; Vaidyanadhan, 1971; Yashpal et al., 1980).
Abstract
Drainages have characteristic pattern and life histories with youthful stage in hilly areas, mature stage in plains and old stage in the coastal zones. The deviations from their normal life histories, especially aberrations in their flow pattern in the form of various drainage anomalies have been inferred to be the indications of dominantly the Eustatic and Isostatic changes. This, especially after the advent of Earth Observing Satellites, 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 comprehensively map some drainage anomalies like deflected drainages, eyed drainages and compressed meanders and to evolve the tectonic scenario therefrom. The mapping of such mega drainage anomalies and the related lineaments/faults from the satellite digital data and the integration of such lineaments/faults with the overall lineament map of South India showed that the study area is marked by active N–S block faults and 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.
Introduction
Rivers have characteristic pattern and life histories with (1) short and straight drainages performing only erosion in the hilly catchments, (2) meandering and sinuous paths doing both erosion and deposition in the plains and (3) Brownian pattern of movement doing only dumping of sediments and building up of deltas in the coastal zones. Such characteristic life history of the rivers with youthful stage in the hills, mature stage in the plains and the old stage in the coastal zones in general are controlled by the base level of erosion or Mean Sea Level (Thornbury, 1985). But, the rock types and the geological structures of the terrain related to palaeo, time transgressive and ongoing tectonism too significantly control the drainage pattern and the related river flow dynamics in all these three stages. Hence, geoscientists from all over the world have all along been showing greater interest in understanding the drainage architecture in general and their anomalies in particular. That too, after the advent of Earth Observing Satellite technology, mapping of drainage pattern and their anomalies like dentritic, semi dentritic, trellis, parallel, annular, radial, deflected, pirated, avulted, eyed, compressed, preferentially migrated and other drainage anomalies have gained greater momentum, since, besides lithology, tectonics and sea level changes, these drainage anomalies have the credibility of providing information on the flood histories, seismic vulnerability, past climates and anthropogenic phenomenon too (Chitale, 1970; Chen and Stanley, 1995; Lillesand, 1989; Matmon et al., 1999; Miller, 1937; Reid, 1992; Saintot et al., 1999; Smith et al., 1997; Twidale, 2004; Thornbury, 1985 and many others). In different parts of the Indian sub-continent too, studies have been carried out on the drainage anomalies using topographic sheets, black and white panchromatic aerial photographs and orbital multimode and multispectral satellite data, to elucidate the structural fabric, tectonic processes, climatological and other phenomenon of especially the Quaternary period (Amalkar, 1988; Babu, 1975; Bakliwal and Sharma, 1980; Barooah and Bhattacharya, 1989; Mitra et al., 2005; Murty and Mishra, 1981; Narasimhan, 1990; Oldham et al., 1901; Philip et al., 1989; Rajaguru and Kale, 1985; Ramasamy, 1991, 2006; Ramasamy and Kumanan, 2000; Ramasamy et al., 1987, 1991, 2006; Singh et al., 1996; Sood et al., 1982; Thirunaranan, 1938; Vaidyanadhan, 1971; Yashpal et al., 1980).