GROUND PENETRATING RADAR STUDY OF PALEOCHANNELS OF THE TERMINAL FANS IN PARTS OF THE GANGA PLAIN AND THEIR PALEOTECTONIC AND PALEOCLIMATIC IMPLICATIONS

Abstract

Terminal fans occur at the end of inland streams when the streams decrease in size and deposit sediments due to high evaporation losses or/and relief change. These terminal fans are widely present in the Indo-Gangetic plain. The Indo- Gangetic plain itself is divided into six tectonics blocks delineated by various rivers flowing through the plain. These blocks formed as a result of various neotectonic activities. Between these tectonically active times, there were relatively stable times that allowed and deposition of sediments over these terminal fans and thus essentially converting the streams of these terminal fans into paleochannels. The current thesis project aimed at detecting these paleochannels in the Ghaggar- Yamuna and Yamuna-Ganga block of the Upper Ganga plain with the help of Ground Penetrating Radar (GPR) survey. GPR survey conducted during the thesis used a 100 MHz frequency antenna with a common offset technique in the Distance mode of GPR data acquisition. The profiles along which the GPR survey was conducted were almost always transverse to the direction of the channel flow so that maximum amount of variation could be detected. The survey was conducted on East Muzaffarnagar Fan, Middle Muzaffarnagar Fan, West Muzaffarnagar Fan of the Yamuna-Ganga Block and Markanda Fan, Old Yamuna Fan, Young Chautang Fan- II, Young Chautang Fan- III, Sonipat Fan of the Ghaggar-Yamuna Block. The acquired data has been processed with the help of RADAN 5.0 software using various appropriate processing techniques. A paleochannel is present as a saucer shaped structure of varying degree of sizes in the GPR section. Several reasonable GPR sections of paleochannels have been detected from different terminal fans. By making the use of the available Neotectonics data, these detected paleochannels has been put in place in the geological history of the Indo-Gangetic plain in the context of faulting episodes and consequently terminal fan formation.