Department Of Geology

Permanent URI for this community

http://10.2.3.109/handle/32116/94

Browse

Browsing Department Of Geology by Author "Amrutha, K."

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Clay minerals as paleo-climate proxy in Quaternary Dun sediments, NW Himalaya, India
    (Springer Science and Business Media Deutschland GmbH, 2023-10-17T00:00:00) Amrutha, K.; Ahmad, Samad; Kumar, Pankaj; Pattanaik, Jitendra Kumar
    Purpose: Clay mineral assemblages are widely used for deciphering paleoclimatic information, where diagenetic and detrital clays provide different signatures. The type and amount of clay present in the alluvial fan sediments account for the prevailing climate, topography, transport dynamics, diagenesis, and lithology of the catchment area. Clay mineral analysis of sediments collected from the younger lobe of Kiratpur Fan, Pinjaur dun, NW Himalaya, will help to understand the late-Quaternary climatic perturbations during marine isotope stage (MIS)-3 and to evaluate the suitability of clay minerals as paleoclimatic proxy. Materials and methods: Samples were collected from three sites along the Kiratpur Nadi near Paploha village, Haryana, where exposed sections had a total height of ~ 28�m. In this study, 31 samples from these sediment sections were collected and after initial processing, clay minerals were separated and oriented slides were prepared. These samples were analysed using X-ray diffractometer (XRD) with/without glycolation and heating treatments. One aliquot of dried clay from selected samples were used for FTIR to complement the XRD analysis. For FTIR analysis, about 1�mg of clay samples was mixed with ~ 10�mg of KBr and press pellets were prepared. Results and discussion: The clay fraction of these sediments constitute illite (~ 52 � 0.8%), kaolinite (~ 13 � 1.6%), and chlorite-montmorillonite interstratified clay (~ 35 � 1.5%). Shale and mudstone distributed in the catchment area might be the source of these clay minerals. Illite chemistry index of ~ 0.37 � 0.14, kaolinite/illite ratio (0.21�0.29), illite crystallinity (IC) (0.23 � 0.04), and kaolinite percentage suggest the dominance of physical weathering in the catchment area. These sediments are generated during a cold and dry period, and deposited during an aggradational phase associated with warm and wet phase within MIS-3 (40�30 Ka). Further, it was found that illite is the dominant clay throughout the Himalayas, Ganga plain, and Bay of Bengal (BoB) sediments, irrespective of their distance from the source. Hence, associating illite to younger and less-transported sediment does not work in this setting. Conclusion: Though the proxies based on clay percentage is very useful, only limited data is available. There is a significant difference in the value of IC in the Himalayan front and BoB sediments may be due to the modifications during the transportation of sediments. Overall, when sediments are transported for a longer distance, correlating clay mineral percentage with the maturity of sediment is not apparent. � 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
  • No Thumbnail Available
    Item
    Climate Change Impact on Major River Basins in the Indian Himalayan Region: Risk Assessment and Sustainable Management
    (Springer International Publishing, 2023-03-10T00:00:00) Amrutha, K.; Patnaik, Rasmi; Sandeep, A.S.; Pattanaik, Jitendra Kumar
    Billions of people relay on water resources of the Himalayan region for drinking, irrigation, and other domestic purposes. Abundance of natural resources makes this region suitable for human settlements, despite the fact that the area experiences frequent natural hazards. Water resources including major rivers are one of the important components, responsible for high biodiversity of the Himalayas and its role in global atmospheric circulation. Recent climate changes have proved to affect the precipitation pattern and ice cover of the Himalayas, causing variations in the dynamics of rivers in the area. Climate change�induced variation in river flow quantity, timing, and unpredictability raises the danger of ecological changes and has a negative impact on aquatic life and the ecosystem depending on rivers. Agriculture is one important sector that is at highest risk due to climate change. This is a serious concern as the runoff patterns of the rivers are mainly determined by the precipitation pattern and ice cover in the upper reaches. Reduction in ice cover reduces the water storage capacity of the Himalayas, and fluctuations in the precipitation pattern cause floods and droughts. The increased frequency of natural hazards including floods and droughts affects the economy and is a threat to people�s life. Climate change effects on water resources, namely, Himalayan snow and ice reservoirs and lake and river systems and the risk associated with it, can be monitored using different hydrological models. To cover vast geographical areas of the Himalayan region, adequate hydrological observatories need to be installed in order to monitor and record time series data of the hydrological parameters. Systematic monitoring will help to predict how climate change will affect water resources in the future. Sustainable management of local resources based on suitable practices, adaptation strategies, and need-specific policies relevant to basin climate can further reduce frequent climate change-related impacts, risk, and vulnerability. � The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.
  • No Thumbnail Available
    Item
    Reconstruction of Quaternary climate in Svalbard: CRN as proxy
    (Elsevier, 2021-08-27T00:00:00) Amrutha, K.; Kumar, Pankaj; Khare, Neloy; Pattanaik, Jitendra Kumar
    Polar region experienced a large-scale melting of glaciers and sea ice retreat in the recent past. Drastic decrease of ice cover and its foreseen impact on ocean circulations, sea level, and ocean chemistry brought Arctic into the forefront of climate change studies. High-latitude glaciers withstand minor climatic change. However, recent trend of global climatic conditions started influencing polar ice sheet and glacier to an alarming state. Compared to lower latitudes, Arctic is significantly affected by minor changes in temperature and precipitation pattern, referred as �Arctic amplification.� Ice dynamics and impact of climate change on Antarctica ice sheet is different than the Arctic Circle as the surrounding environment and atmospheric circulations acting in these areas are diverse in nature. External forces like Milankovitch Cycles and solar irradiance; atmospheric forces like greenhouse gas concentrations, albedo, and cloud cover; and interaction among these forces are key factors responsible for prevailing climate and its changes in the Arctic Circle. Since few decades, Arctic Circle witnessed complex atmospheric, oceanic, and terrestrial changes. Location of Svalbard archipelago is very crucial in terms of the ocean circulation as it is lying between North Atlantic Ocean and Arctic Ocean. The climate here is largely governed by the North Atlantic Oscillation and thermohaline circulation. However, rise in annual average temperature of Arctic is linked to increase in CO2 concentration and decrease in SO4 gas in the atmosphere. Study suggests that role of SO4 concentration in the atmosphere is more important than the solar irradiation in the Arctic climate. Therefore it is essential to understand how climate has responded to external and atmospheric forces. Svalbard located in the North Atlantic sector of Arctic region has shown a high response to present climate changes due to multiple feedback mechanisms associated with oceanic, atmospheric, and cryosphere processes. � 2021 Elsevier Inc. All rights reserved.