Abstract
The basement in Upper Assam foreland basin exhibits a typical flexure pattern. An elongated continuous subsurface basement high has developed between Himalaya and Naga-Patkai ranges. A few prominent basement lows have developed adjacent to the foothill regions. It is noticed that the general topographic slope near the foothill regions is not only controlled by aggradation process, but also influenced by the flexured basement of the region. The basement lows have influenced the overlying topography significantly. Rivers flowing over those regions have shown unidirectional lateral migration. North bank tributaries like Subansiri, Jiadhal and Dikrang have been affected by the Subansiri basement low. Coseismic subsidence of sediments over Subansiri basement low had resulted subsidence of the North Lakhimpur-Ranga Nadi region in 1950 Assam earthquake. Some south bank tributaries like Disang and Dikhow have been affected by Nazira basement low. Topographic elevation along the Subansiri river is lower than that part of the Brahmaputra located south of Majuli. This typical topographic setting of the region makes the mouth of the Subansiri river and Majuli region highly susceptible to erosion.
Highlights
The Upper Assam valley is a part of the Himalayan foreland basin covered by Tertiary sequences and Recent alluvium. Sarma (2005) has given accounts on the fluvial processes and morphology of the Brahmaputra river in Assam valley. Goswami (1985) has studied the channel aggradation process of the river
The general topographic slopes near the foothills of Naga-Patkai and Himalayan ranges are controlled by aggradation process, and influenced by the flexured basement of the region, it is buried under a thick pile of sediment
We argue that the Nazira region over Nazira basement low underwent coseismic subsidence during any historical earthquake
Summary
The Upper Assam valley is a part of the Himalayan foreland basin covered by Tertiary sequences and Recent alluvium. Sarma (2005) has given accounts on the fluvial processes and morphology of the Brahmaputra river in Assam valley. Goswami (1985) has studied the channel aggradation process of the river. Details on active tectonics of the Brahmaputra valley are given in the works by Das and Saraf (2007), Das et al (2007), Das (2010), Sarma, Acharjee, and Gogoi (2011), Lahiri and Sinha (2012, 2014), Sharma and Sarma (2013). In contrast to these studies, some basement structures within the valley region have not received adequate attention of the researchers. Some tributaries of Brahmaputra have been affected by active tectonics of basement structures
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
