Drainage Analysis in a Part of the Brahmaputra Valley in Sivasagar District, Assam, India, to Detect the Role of Neotect
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RESEARCH ARTICLE
Drainage Analysis in a Part of the Brahmaputra Valley in Sivasagar District, Assam, India, to Detect the Role of Neotectonic Activity Sangeeta Sharma & Jogendra Nath Sarma
Received: 24 April 2012 / Accepted: 14 January 2013 # Indian Society of Remote Sensing 2013
Abstract An analysis of the drainage network of a part of Sivasagar district, Assam, India, is undertaken to reveal the role of neotectonic activity of the area. A number of fluvial geomorphic anomalies have been identified in the area. A prominent annular drainage anomaly is displayed by the major rivers—the Dikhu, Jhanzi, Namdang, Dorika and Disang, whose courses are carved in response to the ongoing tectonic deformation in the area. This study reveals that the development of topography and drainage system of the study area have been influenced by active subsurface geological structures. Formation of paleochannels, compressed meanders, reticulate streams, swamps, sagging of grounds, stream alignments, lineaments, knick points and abandonment of rivers as well as development of smaller drainage anomalies also substantiate the active nature of the subsurface structures. Keywords Geomorphic anomaly . Tectonic deformation . Neotectonic activity . Drainage anomaly
S. Sharma (*) GeoScience Division, CSIR-North East Institute of Science and Technology, Jorhat-6, Assam, India e-mail: [email protected] J. N. Sarma Department of Applied Geology, Dibrugarh University, Dibrugarh-4, Assam, India
Introduction Neotectonics refers to recent tectonic movements occurred in the upper part of Tertiary (Neogene) and in the Quaternary, which played an essential role in the origin of the contemporary topography (Obruchev 1948). Uplift by mountain-building forces changes fluvial landscapes (Bull 2007). The analysis of drainage networks is a powerful tool to detect recent tectonic activity and uplift (Ouchi 1985; Clark et al. 2004). A number of fluvial geomorphic anomalies have been identified in the drainage basins of the Dikhu and Jhanzi rivers within the Brahmaputra valley in Sivasagar district of Assam. The Brahmaputra valley is located in a tectonically active and complicated structural region which falls under Seismic zone V of India (BMTPC 2003; Vulnerability Atlas of India 2006). The Himalayan orogenic belt in the north, the Naga Patkai belt in the south and the Syntaxial bend in the east have been controlling deposition of the stratigraphic formations and development of structural features throughout the Tertiary period till Recent time. Hence some of the observed drainage anomalies and geomorphic features have been influenced by recent tectonic activity within the Brahmaputra valley. Some drainage anomalies of the Brahmaputra valley have been described earlier by different authors like Roy (1975); Sarma and Basumallick (1984); Kunte (1988); Pahari et al. (2008) etc., but influence of active subsurface structures on the development of the drainage anomalies has not been attempted so far
J Indian Soc Remote Sens
in this region. Valdiya (19
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