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Tectonic instability of the petroliferous upper Assam valley (NE India): A geomorphic approach
Journal
Journal of Earth System Science
ISSN
23474327
Date Issued
2022-03-01
Author(s)
Gogoi, Manash Pratim
Gogoi, Bikash
Mukherjee, Soumyajit
Abstract
Tectonic (in)stability of terrains is of major concern in financial investment for hydrocarbon exploration from such terrains. Morphometric studies of a river can explain neotectonics of the terrain. This study presents the southeast (SE) frontier of the Brahmaputra river valley of the upper part of the state of Assam, northeast India, where geomorphic changes are observed through remote sensing studies. Two primary geomorphic observations of the study are: (1) formation of palaeostream at the valley due to cut-off of headwater discharge due to the activation of frontal thrust (Naga thrust) along the SE boundary of the valley and the Naga Hills (Assam–Arakan fold-thrust belt), and (2) shifting of confluence points Lohit river (tributary of the Brahmaputra river) causing avulsion and formation of a river island (Dibru Saikhowa). The first event is related to the recent tectonic activities, i.e., uplift of a fault-propagation fold (Digboi anticline). The later event of migration of the Lohit river might be associated with tilting of the SE side of the basin due to activities along the blind thrust systems of the Himalayan foot-hills and the basement high over the last 25 years. This gradually elongated its drainage basins. The southern propagation of the frontal thrust systems of Arunachal Himalaya and Mishmi hills has already shifted the course of the Lohit river towards the south leading to significant changes in geomorphology over the last few decades. N–S-oriented compressional stress axis apparently indicates possible movements along the fault systems bounding the inter-drainage basin facilitating the fluvio-morphometric changes.
Volume
131
Subjects