The area of the present investigation’s expanse constitutes the southernmost extent of the southeast Kumaun Himalaya and western Nepal Himalaya.Multidisciplinary approaches have been employed to understand the landfo...The area of the present investigation’s expanse constitutes the southernmost extent of the southeast Kumaun Himalaya and western Nepal Himalaya.Multidisciplinary approaches have been employed to understand the landforms associated with tectonic deformation,through detailed field investigation supplemented by the geodetic,chronological,and morphometric database.The morphogenic expressions of the Main Boundary Thrust(MBT)are reflected in the form of~25 km long E-W trending north dipping fault scarp.The deformation along the strike length of the Himalayan Frontal Thrust(HFT)is noticed in the form of uplifted and incised fill terraces,and strath terraces.The deformation within the fluvial sequences in the study area can be visualized in the form of sheared boulders and pebbles,tilted and faulted terrace deposits.Furthermore,the chronological data of fluvial landforms in the study area suggests two major phases of tectonic deformations that have occurred around 58.7±10.8 ka and 3.88±0.4 ka.The chronology of late-Quaternary landforms advocates that the initial stage of aggradations in the Himalayan foothills commenced around 75.1±0.58 ka.The aggradational landforms resulted from the diverse depositional regime as evident from the nature of the sediment sequences from clasts dominated to thick mud sequences.The rate of deformation in the southeastern Kumaun and western Nepal Himalaya is±7 mm/yr,as per the data obtained from the Persistent Scatterer Interferometric Synthetic Aperture Radar(PSInSAR).The landform deformation pattern,phase of incision and aggradation,frequent occurrence of landslides,and recent past earthquake activity within the wide zone of the HFT,the MBT,and Ramgarh Thrust suggests that the southernmost front of the Kumaun Himalaya is active and has potential for future geohazard.The foothill zone of Himalayan towns are actively growing in terms of population and infrastructural development.Therefore,such intradisciplinary studies for tectonically active regions are needed for future infrastructural development.展开更多
The existing literature discussed only the aerial aspect and provided a brief description of tectonic-geomorphic correlation with field evidence.In present study we applied power law equations to estimate basin asymme...The existing literature discussed only the aerial aspect and provided a brief description of tectonic-geomorphic correlation with field evidence.In present study we applied power law equations to estimate basin asymmetry factor(AF),Transverse topographic asymmetric factor(T),Hypsometric Integral(HI),longitudinal profile,stream length gradient index(SL),steepness index(Ksn),Chi(χ),and knick point(Kp)analysis to examine the response of tectono-climatic fluctuations in the Mandakini River basin,central Uttarakhand Himalaya.To decouple the causative tectono-climatic factors,we employed geospatial and Stream Power Incision Modeling(SPIM)techniques.SPIM is a globally accepted tool to predict an equilibrium state between fluvial erosion rates and the escalating function of stream power.It is actively applied in modeling the transformation of river systems especially in rugged topographic regions.The present study covers SPIM-based morphometric assessment of the tectonically sensitive Mandakini River basin between Ramgarh Thrust(RT)and Vaikrita Thrust(VT)in the central region of Uttarakhand Himalaya.In the upper reaches of the basin,U-shaped glaciated valleys dominate the landscape,while a rolling topography and deeply incised narrow valleys are depicted towards the downstream.Therefore,to understand the response of active tectonic over geomorphology,the drainage basin has been divided into two separate zones from the confluence point near the Rampur area.The modeling outcomes indicate that the Mandakini drainage basin is in a disequilibrium state where channels are actively incising to bedrock.Overall,AF of 32 and 70 indicate leftward tilting in the upper reaches and rightward tilting in the lower reaches of the basin,respectively.The HI value of 0.38 indicates a stage of maturity,characterized by a concave shape profile.Based on the analysis it may be concluded that the fragile lithology and tectono-climatic fluctuations are dominantly controlling the topography and valley floor morphology of the Mandakini River.展开更多
基金Council of Scientific and Innovative Research for providing fellowship (file number- 09/0420(15968)/2022-EMRI)
文摘The area of the present investigation’s expanse constitutes the southernmost extent of the southeast Kumaun Himalaya and western Nepal Himalaya.Multidisciplinary approaches have been employed to understand the landforms associated with tectonic deformation,through detailed field investigation supplemented by the geodetic,chronological,and morphometric database.The morphogenic expressions of the Main Boundary Thrust(MBT)are reflected in the form of~25 km long E-W trending north dipping fault scarp.The deformation along the strike length of the Himalayan Frontal Thrust(HFT)is noticed in the form of uplifted and incised fill terraces,and strath terraces.The deformation within the fluvial sequences in the study area can be visualized in the form of sheared boulders and pebbles,tilted and faulted terrace deposits.Furthermore,the chronological data of fluvial landforms in the study area suggests two major phases of tectonic deformations that have occurred around 58.7±10.8 ka and 3.88±0.4 ka.The chronology of late-Quaternary landforms advocates that the initial stage of aggradations in the Himalayan foothills commenced around 75.1±0.58 ka.The aggradational landforms resulted from the diverse depositional regime as evident from the nature of the sediment sequences from clasts dominated to thick mud sequences.The rate of deformation in the southeastern Kumaun and western Nepal Himalaya is±7 mm/yr,as per the data obtained from the Persistent Scatterer Interferometric Synthetic Aperture Radar(PSInSAR).The landform deformation pattern,phase of incision and aggradation,frequent occurrence of landslides,and recent past earthquake activity within the wide zone of the HFT,the MBT,and Ramgarh Thrust suggests that the southernmost front of the Kumaun Himalaya is active and has potential for future geohazard.The foothill zone of Himalayan towns are actively growing in terms of population and infrastructural development.Therefore,such intradisciplinary studies for tectonically active regions are needed for future infrastructural development.
基金The authors are thankful to the UPES,Dehradun and the Department of Science and Technology,Govt of India(Project:CRG/2023/000555)for supporting this study.
文摘The existing literature discussed only the aerial aspect and provided a brief description of tectonic-geomorphic correlation with field evidence.In present study we applied power law equations to estimate basin asymmetry factor(AF),Transverse topographic asymmetric factor(T),Hypsometric Integral(HI),longitudinal profile,stream length gradient index(SL),steepness index(Ksn),Chi(χ),and knick point(Kp)analysis to examine the response of tectono-climatic fluctuations in the Mandakini River basin,central Uttarakhand Himalaya.To decouple the causative tectono-climatic factors,we employed geospatial and Stream Power Incision Modeling(SPIM)techniques.SPIM is a globally accepted tool to predict an equilibrium state between fluvial erosion rates and the escalating function of stream power.It is actively applied in modeling the transformation of river systems especially in rugged topographic regions.The present study covers SPIM-based morphometric assessment of the tectonically sensitive Mandakini River basin between Ramgarh Thrust(RT)and Vaikrita Thrust(VT)in the central region of Uttarakhand Himalaya.In the upper reaches of the basin,U-shaped glaciated valleys dominate the landscape,while a rolling topography and deeply incised narrow valleys are depicted towards the downstream.Therefore,to understand the response of active tectonic over geomorphology,the drainage basin has been divided into two separate zones from the confluence point near the Rampur area.The modeling outcomes indicate that the Mandakini drainage basin is in a disequilibrium state where channels are actively incising to bedrock.Overall,AF of 32 and 70 indicate leftward tilting in the upper reaches and rightward tilting in the lower reaches of the basin,respectively.The HI value of 0.38 indicates a stage of maturity,characterized by a concave shape profile.Based on the analysis it may be concluded that the fragile lithology and tectono-climatic fluctuations are dominantly controlling the topography and valley floor morphology of the Mandakini River.
