Department of Geology

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Browsing Department of Geology by Subject "Geosciences"

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    Efficacy Appraisal of Synthetic Bimetallic Nano‐ aggregates for Fluoride Removal from Drinking Water through Batch and Fixed‐Bed Column Operation Technology
    Palani, Sasikumar
    Water is the elixir of life. Supply of pure and safe drinking water forms the lifeline of existence. Therefore, adequate supply of good quality drinking water is the basic need of all human beings on earth; but millions of people worldwide are deprived of this vital natural resource. Safe water for all can only be assured when access, sustainability, quality and equity can be guaranteed. It is an established fact that that many groundwater and surface water sources across the world are now contaminated with toxic chemicals that cause severe water-borne diseases in man and animals. Fluoride contamination (>1.5 mg.L-1) of drinking water is one such problem worldwide that has taken the shape of a burning environmental issue. At present, 32 countries across the world are reported to be affected with fluorosis - the disease caused by intake of fluoride infested drinking water. The problem has also been reported from India for quite a long time. But lately, it has turned into a natural calamity in India. Fluoride greater than 1.5 mg L-1 in water causes dental, skeletal and non-skeletal fluorosis. Again, fluoride less than 0.5 mg L-1 in water causes dental caries. This peculiar bio-chemical behaviour of fluoride has put a restriction on the use of groundwater for drinking without opting for prior removal (treatment) of fluoride. Several physiochemical techniques, such as adsorption, ion exchange, lime softening, reverse osmosis, coagulation and precipitation for arsenic removal has drawn great attention in the past two decades. Among these techniques, adsorption is mainly used because of its simplicity to use and availability of a wide range of adsorbents. This research work predominantly concentrated on development of a bi-metallic oxide nanocomposites as novel adsorbent that can effectively use for fluoride removal from groundwater. Iron is selected as the base element of this metal oxide mixture for its extreme natural abundance and excellent pollution scavenging property. Cerium experimentally proven to possess strong affinity to form chemical linkage with fluoride. Therefore, combinations of iron with cerium in varying proportions could be undertaken to increase the surface area and number of surface active sites. As a part of the present research programme, a crystalline nanoaggregates of [Fe(III)–Ce(IV)] named as CIHFO, prepared in the laboratory based on certain physico-chemical parameters and principles. Simultaneously the studies deal with a series of adsorption experiment (batch and column) to assess the potentiality of the CIHFO for removal of fluoride from groundwater. Further surface modification of Ce (IV)-incorporated hydrous Fe (III) oxide (CIHFO) with hydrophilic graphene precursor (GO) and β-CD moiety successfully achieved by in-situ wet chemical deposition method for improvement of structural integrity of said adsorbent and also adsorption capacity of CIHFO. The effectiveness of these three adsorbents was also censoriously explored by treating with contaminated groundwater collected form fluoride affected area with an aim that a novel treatment technique can be provided to the fluoride contaminated region.
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    Evolution of Cambay Basin, western India during the Eocene from the study of gastropods and shell beds
    Halder, Kalyan
    During the early Palaeogene western India was flooded with extensive transgressions. The first marine sediments were deposited in the western marginal basins during the Ypresian, i.e., early Eocene. Molluscs, including gastropods, bivalves and scaphopods, appeared and flourished in these basins, within the transitional habitats between sea and land. The early Cenozoic time was important for the evolutionary history of gastropods because several of the gastropod groups, abundant in modern-day seas, either first appeared or went through rapid diversifications and distributions during this time. While comprehensive monographs about the Paleocene-Eocene gastropods are available from the European and North American basins, and even the adjacent Pakistan basins, the Indian basins remained relatively less explored. Among the western Indian basins, most of the published reports came from the Kutch Basin, a few from the Subathu and Rajasthan basins and none from the Cambay Basin. The gastropods present in the Ypresian Cambay Shale of the Cambay Basin are studied here. 32 caenogastropods and 9 heterobranchs are reported and described. 32 of them (24 caenogastropods and 8 heterobranchs) are new. 13 of them are microgastropod (< 4 mm). 3 new genera and 2 new subgenera are introduced. The fossils were collected from four lignite mines at Mangrol, Vastan, Tadkeshwar and Valia, Gujarat. The Camaby Shale is an argillaceous formation with intercalations of lignite seams and marine fossil bearing limestones. Glauconitic green shale layers and shell beds dominated by only one or a few opportunist molluscs yielded gastropods of eurytopic or marginal marine affinity. A change from the freshwater-dominated coastal swamp to a relatively open-marine condition in an overall marginal marine set-up could be deciphered from the sequence of lithologies and fossils. The composition, diversity-abundance pattern, environmental preference and trophic structure of the molluscs, especially gastropods, elucidate this transgressive sequence. The Cambay gastropod assemblage predominantly comprises endemic species and widespread genera. A similar pattern was unveiled by the Paleocene-Eocene gastropod faunas reported from all Indian and Pakistan basins, situated within the Western Indian Province (WIP). The wide distribution of the genera took place due to the faunal exchanges via the circum-tropical equatorial currents along the relict Tethys, Atlantic and Pacific oceans. The westerly flowing somewhat weak Tethys current was important for migration of western Indian faunas. However, the specific endemism is enigmatic because a large part of the fauna had planktotrophic development. The restricted nature of the basins might be a significant factor. The early developmental mode was not found to be a decisive factor in the geographic distribution of the WIP gastropods at both generic and specific levels. The maximum geographic distribution and also, temporal duration of these genera were found to be not significantly different among the WIP genera characterized by planktotrophy, non-planktotrophy (lecithotrophic/direct), and a combination of these. With greater time, the maximum geographic distribution became broader. Also, majority of these genera were found to attain their maximum geographic distribution at the early stages of their temporal ranges. The changes in the maximum latitudes of these genera support their migration towards higher latitudes during the warming and towards lower latitudes during cooling periods, in response to the climatic turnovers of the Palaeogene.
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    Sedimentological Analyses, Internal Stratigraphy and Sediment hosted Detrital Iron and Radioactive Ore Mineral Potential of the Mesoarchean Siliciclastic Succession around Keonjhar, Singhbhum Craton, Odisha, India
    Mukhopadhyay, Joydip
    The Keonjhar siliciclastics in the Singhbhum craton, eastern India, represents one of the best preserved examples of Mesoarchean sedimentation. This PhD dissertation programme throws light on the depositional system and nature of Mesoarchean upper crust from a collective study of internal stratigraphic development, depositional settings and provenance. The succession is classified here as a formal lithostratigraphic unit of the rank of formation and named as Keonjhar Quartzite. Two members have been proposed, namely, the Asurkhol Member that forms the lower conglomerate-pebbly sandstone-coarser sandstone dominated part and a lentil of iron ore clast-bearing conglomerate at the upper part, namely, the Chamakpur Member. Facies analysis reveals that the lower part of the succession is dominated by mass-flow deposits of conglomerates from proximal subaerial fan which grades upwards to cross-stratified and wavy bedded mature arenites of shelf depositional setting. The sequence includes a LST with Incised Valley Fills from FSST followed by a TST and TSTHST. Petrographic study depicts recycled orogen to craton interior provenance. SEM-CL fabric analysis of the quartz framework grains reveals predominance of plutonic quartz over metamorphic type and suggests that high-grade components from collisional geodynamics were not significant in the Paleo-Mesoarchean upper continental crust in the Singhbhum craton. The superchondritic Hf isotopic compositions expressed as €Hf values against their stratigraphic ages from the detrital zircon LA-ICPMS U-Pb-Lu-Hf compositions suggest depleted mantle source and juvenile crustal components and possible onset of accretionary plate tectonics. Uranium mineralization in the basal QPCs reveals U-concentration in the U-Ti oxides and indicates supergene mobilization of U. Geochemical proxies suggest a passive margin setting with cratonic as well as active margin components. The REE pattern with negative Euanomaly indicates the presence of differentiated upper crust suitable for the source of U-Th minerals for the U-QPCs. The iron ore conglomerate yielded detrital zircon U-Pb ages of around 3.0 Ga. The hard ore clasts in the conglomerate suggest that the ore formation in the source terrain predated the deposition of the conglomerate and hence the primary iron ore genesis at the source from where the ore clasts were derived should be at least >3.0 Ga event.
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    Structural and AMS analyses of basement Granitoid rocks of the Chitrial Area and its bearing on unconformity proximal type Uranium mineralization Cuddapah Basin Telangana
    Ghosh, Gautam
    The 2.51-2.52 Ga age Paleoproterozoic (Mukherjee et al., 2018) basement granitoid rocks of the Chitrial area in the Eastern Dharwar Craton (EDC) are unconformably overlain by the Mesoproterozoic Srisailam Formation (Nagaraja Rao et al., 1987) of the Cuddapah basin. Pre-Srisailam dyke sets (1.9-1.8 Ga; French et al., 2008) of N-S, WNW-ESE and ENE-WSW orientations traverse the granites around the Chitrial outlier. The map scale WNW – ESE trending Dindi lineament marks the southern limit of the outlier. Atomic Minerals Directorate (AMD) in recent times has established several ‘Uranium deposits’ from the Cuddapah basin of which one such deposit has been reported from the Chitrial outlier. In this latter deposit, uranium is hosted in Arechaean to Paleoproterozoic porphyritic basement granite unconformably overlain by the Mesoproteozoic unmetamorphosed sediments of the Srisailam Formation. According to the concentration of uranium mineralization, AMD further divided the Chitrial outlier into five blocks namely the ‘Main block’, ‘Block 1’, ‘Block 2’, ‘Block 3’ and ‘Block 4’.
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    Study of Geomorphic Features of Noachis Terra, Mars: An Insight to Martian Tectonic Processes
    Dasgupta, Nilanjan
    Early cessation of Mars’ internal dynamo has resulted in excellent preservation of geological and geomorphological structures on its surface through time, unlike Earth where almost all the tectonic and geomorphic signatures of antiquities have been destroyed and re-organized. The present study area, Noachis Terra, in the southern highlands of Mars, is one such terrain, where the morphotectonic structures are found to be fossilized within the rocks of all timeframe. These morphotectonic features are the key to the understanding of the palaeo-tectonism and hence are the primary objects of investigations of the present study. This research identifies these features and characterizes each of these in detail. The study presents a detailed morphotectonic map of Noachis Terra in a scale of 1:12,000,000, which was unavailable till date. The entire area was subdivided into four different tectonic domains, each of which was found to have unique tectonic characteristics. These four domains were explored in detail and mapped in the scale of 1:2,500,000 to 1:5,000,000 in this study. The tectonic evolution of the four tectonic domains has been described in this study with the aid of these maps. The control of both emergent and non-emergent tectonic structures on the courses of the Martian channels observed in Domain III and IV of the study area have been statistically tested by cross-correlation methods. Palaeostress analyses done from the orientations of the tectonic structures mapped clearly shows the nature of the shift of the principal stress directions both spatially and temporally in the Noachis Terra. This is significant as it hints to the changing nature of local stress fields vis-à-vis the global stress field of Martian crust. The present study also elaborates on the chronology of the structures, seen in the area, with special emphasis on Domains III and IV. Wrinkle ridges of the western part of Noachis Terra (Domain I) were formed during the early Noachian time under the influence of Tharsis volcano-tectonic province. Large scale grabens in the eastern part of Noachis Terra (Domain II) were formed due to lithospheric stretching related to isostatic adjustment of the Hellas basin during the late Noachian time. The present study reports a set of fossae from the central part of Noachis terra (Domain IV), which was formed in late Noachian time (~3.79 Ga), after the formation of grabens in Domain II. The fossae, identified in the north-western part of the Noachis Terra (Domain III), formed in early Hesperian (~3.69 Ga), are thought to be associated with the Valles Marineris formation. It, therefore, appears that Noachis Terra is a heterogeneous terrain with diverse history of tectonic evolution; the nature of tectonism quite dissimilar to the present day plate tectonism operative on earth.
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    Tectono metamorphic and geochronological evolution of the Rengali Province in the Riamal Rengali Khamar sector Odisha India
    Bose, Sankar
    Rengali Province occupies a unique geographical position between the Archean Singhbhum Craton and the Proterozoic Eastern Ghats Belt of eastern India. This province was variably considered a part of the Singhbhum Craton and/or the Eastern Ghats Belt, but their metamorphic characters are grossly contrasting. This opens a possibility that the Rengali Province evolved as a separate orogenic belt that may be unrelated to the Eastern Ghats Belt. The most striking feature of this province is the occurrence of several linear WNW-ESE trending zones separated by major ductile faults or shear zones. The rocks of this province show varying degree of metamorphism from granulite to greenschist facies. Geological mapping of the central part of the Rengali Province reveals presence of a gneissic basement block intercalated with low-grade supracrustal sequences. The basement rocks are mostly of granitoid composition showing gneissic fabric and the rocks are metamorphosed to amphibolite facies. Enclaves of granulite facies rocks, represented by charnockite gneiss and mafic granulite, occur within the gneissic basement. A part of this gneiss basement, referred to here as the Central Gneissic Belt, is the prime focus of petrological, geochemical and geochronological study. Supracrustal rocks are represented by quartzite, mica schist and calc- silicate schist that belong to the Tikra Association. Detailed structural analyses of the rocks from the central part of Rengali Province suggest that deformation was regionally partitioned into fold-thrust dominated shortening zones alternating with zones of dominant transcurrent deformation bounded between the Barkot Shear Zone in the north and the dextral Kerajang Fault Zone in the south. The strain partitioned zones are further restricted between two regional transverse shear zones, the sinistral Riamol Shear Zone in the west and the dextral Akul Fault Zone in the east. The overall structural disposition can be interpreted as a positive flower structure bounded between the longitudinal and transverse faults with vertical extrusion and symmetric juxtaposition of mid-crustal amphibolite grade basement gneisses over low-grade upper crustal rocks emanating from the central axis of the transpressional belt. The Central Gneissic Belt is constituted of charnockite gneiss, migmatitic hornblende gneiss and felsic gneiss often showing gradational contacts. While mafic granulite occurs as enclave within the charnockite gneiss, amphibolite and calc-silicate granofels enclaves are present within the felsic gneiss. Petrological study shows that the charnockites and mafic granulites underwent granulite facies metamorphism, whereas the gneisses were subjected to amphibolite facies metamorphism. Mafic granulite shows peak metamorphic assemblage of garnet + clinopyroxene + plagioclase + quartz ± orthopyroxene which was stabilized at 10.6 ± 0.5 kbar and 860 ± 20 °C. Charnockite gneiss with the peak assemblage of orthopyroxene +quartz + plagioclase +K-feldspar was metamorphosed at 792 ± 48°C and 7.6 ± 0.4 kbar. Amphibolite and migmatitic hornblende gneiss contain hornblende along with plagioclase and garnet and these rocks were metamorphosed at 800 ± 20 °C, 8.5 ± 0.2 kbar and 695 °C, 8 kbar respectively. Later meta-dolerite dikes exhibit relic igneous textures which are slightly modified by greenschist facies metamorphism. Charnockite gneiss, migmatitic hornblende gneiss and felsic gneiss show similar trace and REE characteristics (moderate fractionation in terms of La and Yb, LREE enrichment and flat HREE pattern) implying the same protolith composition for these rock groups. Field, petrographic and geochemical data suggest that the protoliths for the charnockite gneiss, the migmatitic hornblende gneiss and the felsic gneiss crystallized as fractionated magma in within-plate syncollisional setting during a prominent phase of orogeny at the Rengali Province. Results of detailed zircon U–Pb (SHRIMP) geochronological study of the amphibolite to granulite facies rocks of the Central Gneissic Belt reveal a complex evolutionary history. Charnockitic gneiss has protolith age of 2861 ± 30 Ma and high-grade metamorphism occurred at 2818 ± 15 Ma. Migmatitic hornblende gneiss has a protolith age of 2828 ± 9 Ma. The leucogranite was emplaced at 2807 ± 13 Ma. The protolith of the felsic gneiss was emplaced at 2776 ± 24 Ma. Most of the zircon samples contain overgrowths of c. 2500 Ma, inferred to be the age of reworking of the Central Gneissic Belt. These data suggest that the Rengali Province evolved as an orogenic belt in the Neoarchean time (ca. 2800–2500 Ma) during southward growth of the Singhbhum Craton. These tectonothermal imprints at the margin of the Singhbhum Craton are possibly related to its inclusion within the supercontinent Ur. Interestingly, the rocks of the Central Gneissic Belt and the associated supracrustals do not record any age signatures of ca. 1000-900 Ma orogeny that evolved the Eastern Ghats Province, thus discarding any genetic link between the two adjacent orogenic belts. The later transpression, extrusion and juxtaposition of deep crustal section to shallower level was achieved due to reactivation of the fault-thrust system during ca. 530-500 Ma which can be linked to far field stresses of global Pan-African orogeny.