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Item Geological evolution of the mafic and felsic granulites from the central and northwestern parts of the Eastern Ghats Province in the context of Grenvillian-age tectonicsBose, Sankar; Ghosh, GautamThe Proterozoic Eastern Ghats Belt of eastern India is characterized by a complex evolutionary history punctuated by recurring magmatic, deformation and metamorphic episodes. The terrane is also characterized by extreme thermal structure that resulted from Proterozoic accretionary processes involving continental blocks of India and East Antarctica within the supercontinents Rodinia and Columbia. It consists of rocks that had undergone extreme ultrahigh temperature (UHT) metamorphism at deep crustal level. Due to its geological complexity, the terrane has been classified in terms of various crustal provinces and domains, each displaying distinct tectono-metamorphic characteristics. The centrally occurring Eastern Ghats Province (EGP) evolved during the later part of Proterozoic era. The central (Visakhapatnam domain), northern (Chilka Lake domain) and the northwestern (Phulbani domain) parts of the EGP are composed of migmatitic felsic gneiss, aluminous granulite, fine grained charnockite, felsic augen gneiss, mafic granulite and calc-silicate granulites which are metamorphosed to UHT condition. Following the attainment of peak-UHT condition, all these rocks underwent cooling along a near-isobaric trajectory. The dominant lithological units of the EGP are the orthogneissic rocks, represented by felsic gneiss, charnockite and mafic granulite. Compared to the other rock types like the aluminous granulite and calc-silicate granulite, which are mostly paragneissic in character, geological history of the orthogneissic rocks of this province is poorly known. In a granulite terrane, orthogneissic rocks are essential components of the Earth's lower continental crust and they play crucial roles in the orogenic processes. While mafic granulites are associated with the deeper sections of regional granulite belts, granitic rocks typically occur at lower to mid-crustal levels. Charnockite is diagnostic of Precambrian orogenic belts indicating a connection to the subduction-collision tectonics. Despite their prevalence in the EGP, very few studies have been conducted on mafic granulite, charnockite and felsic gneisses, posing a significant gap in knowledge. This study aims to investigate the geological evolution of orthogneissic rocks, from the central and northern regions of the EGP. By examining their field relationships, mineral evolution, geochemistry, geochronology, and fluid character, this work aims at unravelling the tectonic history of the EGP which is pertinent to the shared geological history of India and East Antarctica. Ultimately, the findings will contribute to the understanding of magmatic and anatectic processes in orogenic crusts and the tectonic evolution of the EGP in the context of the India-East Antarctica correlation. Massif type charnockite was intruded into the lower crust of the EGP and is currently exposed across a vast geographical expanse. The present work is based on charnockite samples collected from different localities of the Visakhapatnam and Phulbani domains of the EGP. These two domains occupy the major part of the central and northwestern part of the province. The rock exhibits distinct signs of its magmatic intrusion into lower crustal metasedimentary rocks, which are preserved as enclaves within the charnockite. The rock displays a range of deformation signatures, spanning from nearly undeformed varieties to highly deformed mylonitized types. The rock comprises primary minerals like orthopyroxene, quartz, K-feldspar (perthitic), plagioclase, ilmenite, ± garnet ± clinopyroxene. Secondary phases in the rock consist of hornblende and biotite. In the relatively less-deformed charnockite samples, magmatic features such as subhedral plagioclase (with primary zoning) and orthopyroxene are preserved. In contrast, the deformed samples exhibit a dynamically recrystallized fabric that shows local transition to a mylonitic fabric characterized by the presence of quartz ribbons. Textural observations indicate that the charnockite magma underwent a process of sub-solidus cooling, followed by metamorphism to granulite facies, reaching temperatures of approximately 910°C at pressures of 9 kbar as estimated from the garnet-orthopyroxene-plagioclase-quartz assemblage. Additionally, this rock preserved some metamorphic texture indicative of potential reworking associated with the second (M2) cycle of metamorphism of the EGP, which has been dated as ca. 950-900 Ma. Geochemical data indicate that the charnockite magma show varying chemical compositions, that possibly resulted from differentiation processes and contamination with the supracrustal materials. This rock exhibits a range of SiO2 content, including both high- and low-SiO2 varieties, displaying characteristics that vary from weakly peraluminous to metaluminous. Notable features include LREE enrichment, HREE depletion, and distinctive trace element patterns. The rock shows enrichment in Ba and positive anomalies of Pb, La, Nd, and Gd, along with negative anomalies of Nb, Ta, Sr, and Ti. Slightly negative Ce and Y anomalies further support evolution of the magma in a post-collisional arc setting. Theoretical modelling indicates that melting of a hydrated basaltic slab in presence of a CO2-rich fluid could be a suitable process for the generation of the charnockite magma. Felsic (granite) gneisses are characterized by porphyritic textures with similar mineralogy like charnockite except absence of orthopyroxene. It has a similar geochemical composition to charnockite, with SiO2, FeOT, and MgO values spanning a broad range and higher K2O concentration. These rocks are predominantly peraluminous, featuring enrichment in LREE and depletion in HREE, with a negative Eu anomaly. Trace element behavior also signifies their evolution in an arc setting. Based on geochemical and intimate field relation of charnockite and felsic gneiss, it can be inferred that these two rocks are differentiated products of same felsic magma under contrasting fluid regimes. The relatively dry nature of the charnockite magma alongside the contemporaneous granite magmatism speaks for the fluctuations in the fluid regime, particularly concerning CO2-H2O components. On the other hand, mafic granulitic rock is less voluminous, occur as enclaves or xenolith within charnockite and felsic gneiss but it plays a pivotal role in the lithological diversity of the EGP. Two distinct types of mafic granulite obtained in this study display somewhat different mineral assemblages and compositions. The two-pyroxene granulite (massive type) contains minerals orthopyroxene, clinopyroxene, plagioclase, magnetite, ilmenite, pyrite, and pyrrhotite. In contrast, the garnet bearing mafic granulite (migmatitic variety) includes an additional phase, garnet. Textural characteristics of both oxide and sulfide minerals differ between these two varieties. Through textural analysis and inferred mineral reactions, it is apparent that the variations in oxide-silicate, oxide-sulfide, and sulfate relationships are associated with changes in oxygen fugacity (fO2) during the pre-peak, peak, and post-peak stages of metamorphism. The determined fO2 values span from a maximum of +4 log units in relation to the QFM (quartz-fayalite-magnetite) buffer for most of the samples, with the exception of a single sample that exhibits lower values, approximately -10 log units concerning the FMQ (fayalite-magnetite-quartz) buffer. The enduringly elevated fO2 state in the lower crust may be attributed to various factors, with the influence of an externally sourced fluid being a credible explanation. The oxidation and localized metasomatism of the mafic lower crust could potentially be explained by the presence of a hot brine solution containing CaCl2 species, despite not being directly confirmed through methods such as fluid inclusion analysis. Sulphide-sulphate relation is also used to understand the fluid regime in shallower crustal level. Zircon U-Pb (LA-ICPMS) obtained in this study from the massif type charnockite from extensive region to understand the precise timing of crystallization of the magma. Crystallization ages were obtained through U-Pb analysis on oscillatory zoned zircon domains from eight samples. Among the majority of the samples, crystallization ages were observed within the range of ca. 980-940 Ma, with specific ages of 978 ± 16 Ma, 968 ± 22 Ma, 951 ± 9 Ma, 954 ± 8 Ma, 951 ± 13 Ma, and 939 ± 27 Ma, respectively. Two samples of charnockite show crystallization age of 1002 ± 13 Ma and 1020 ± 16 Ma. This implies that the emplacement of the charnockite magma was characterized by two distinct phases, and these phases can be associated with the tectono-metamorphic evolution of the province. The earlier phase of charnockite magmatism is indicated to be broadly concurrent with the first cycle (M1) of metamorphism, while the later phase occurred when the lower crust was still experiencing elevated temperatures. The timing of the two charnockite magmatic events aligns closely with the Mawson charnockite in the Rayner Province of East Antarctica. This suggests that the extensive charnockite magmatism in the combined Rayner-Eastern Ghats Province can be attributed to the process of arc-continent accretion and the collision between India and East Antarctica that occurred approximately during ca. 1030-900 Ma.Item Evolution of Cambay Basin, western India during the Eocene from the study of gastropods and shell bedsHalder, KalyanDuring 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.Item Effects of Eocene Global Events on Marine Bivalves from Kutch and Cambay Basins of Gujarat, IndiaHalder, KalyanA series of hyperthermal events coupled with extensive rise in the global mean sea level (GMSL) mark the beginning of Eocene epoch. This time is also characterised by important tectonic rearrangements, especially the long journey and subsequent collision of the Indian plate with the Eurasian plate. The early Eocene (Ypresian) sedimentary deposits from the two western Indian basins, Cambay and Kutch, record five early Eocene hyperthermals. A concomitant marine incursion during the paired events of Eocene Thermal Maximum 2 (ETM2) and H2 has been recorded from both the basins. This led to the deposition of marine mollusc bearing units in an otherwise terrestrial succession of clays and lignite. The stable isotope analyses, sedimentary features and nature of bivalve assemblages indicate a brackish water dominated coastal marginal marine environment throughout the marine succession. A low faunal diversity along with high abundance of certain forms indicate a stressed environment. 36 bivalve species, including 18 new species and two new genera, have been documented from the fossiliferous strata of Cambay Shale. A global palaeobiogeographic analysis based on all Paleogene bivalve genera revealed that the tropical and subtropical latitudes of the Northern Hemisphere, especially Europe and America, hosted the most diverse bivalve assemblage throughout the Paleogene. The Paleocene-Eocene transition exhibited faunal migration to higher latitudes and relatively higher rate of extinction from high latitudes in response to the Paleocene-Eocene Thermal Maximum (PETM). The diversity declined severely in the Oligocene due to global cooling. It also caused latitudinal range contraction of bivalves from high latitudes and a significant extinction from lower latitudes. High endemism and narrow geographical ranges of the Eocene bivalve species within the Western Indian Province (WIP) indicate low dispersibility and rapid allopatric speciation. The westerly flowing Tethyan palaeo-current through the relict Tethys was the main dispersal agent of the Ypresian WIP bivalves until the Lutetian. The collision of Indian and Eurasian plates in the late Eocene (~40Ma) blocked this pathway. In response, a counter flow of the South Equatorial Current established a relation between WIP and south-east Asian localities since the BartonianItem Structural and AMS analyses of basement Granitoid rocks of the Chitrial Area and its bearing on unconformity proximal type Uranium mineralization Cuddapah Basin TelanganaGhosh, GautamThe 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’.Item Study of Geomorphic Features of Noachis Terra, Mars: An Insight to Martian Tectonic ProcessesDasgupta, NilanjanEarly 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.Item Efficacy Appraisal of Synthetic Bimetallic Nano‐ aggregates for Fluoride Removal from Drinking Water through Batch and Fixed‐Bed Column Operation TechnologyPalani, SasikumarWater 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.Item Tectonothermal History of the Granulites and gneisses around Phulbani Odisha India and its bearing on the Evolution of the Proterozoic Eastern Ghats BeltBose, SankarThe Proterozoic Eastern Ghats Belt of eastern India is a key terrane to understand the evolution of the India-East Antarctica blocks of the supercontinent Rodinia. This belt is known for lower crustal rocks that experienced ultrahigh temperature (UHT) metamorphism. Because of its geological diversity, this belt has been subdivided into several crustal provinces and domains each having discrete tectonometamorphic characters. Most of the petrological history of this belt is reported from the domains located at the central (Visakhapatnam domain) and the southern (Ongole domain) parts and while the vast area covering the northern part of this high-grade terrane remains unexplored. The present work has been carried out on the Phulbani domain which occupies a major portion of the north-western part of the belt. Apart from some isolated geochronological data, no systematic petrological, geochronological, structural and fluid investigation has been carried out from this domain. This poses severe constraints on the overall metamorphic history of the northern part of the Eastern Ghats Belt (Eastern Ghats Province) and its connection with the supercontinent Rodinia. In the present study, an attempt has been made to overcome these issues by constraining the geological history of the Phulbani domain in a holistic manner. Phulbani domain is composed of migmatitic felsic gneiss, felsic augen gneiss, fine-grained charnockite gneiss, aluminous granulite, calc-silicate granulite and mafic granulite which was metamorphosed at UHT condition and subsequently intruded by coarse-grained charnockite. The mineral assemblage formed at the peak-UHT metamorphic condition is best documented in the aluminous granulite as spinel+quartz-bearing mineral assemblage. Using textural, thermobarometric and phase equilibria data, it is inferred that the latter mineral assemblage stabilized at 950°C (at approximately 8 kbar) from a corundum-bearing mineral assemblage by chemical reactions during prograde heating. Scapolite-clinopyroxene-wollastonite-plagioclase bearing mineral assemblage in the calc-silicate granulite also indicates temperature in excess of 800°C which is corroborated by high anorthite content of scapolite. After attainment of peak-UHT condition, all the rocks including coarse-grained charnockite experienced pronounced phase of near-isobaric cooling along an almost isobaric prograde and retrograde path and produced coronal garnet in aluminous granulite, calc-silicate granulite, fine-grained charnockite gneiss and coarse-grained charnockite. From the fluid inclusion analyses, it is inferred that the peak- to post-peak metamorphic evolution of the Phulbani domain dominantly occurred in a CO2-dominated fluid regime as high-density (up to 1.03 gm/cm3) CO2-rich fluid inclusions are documented in aluminous granulite, coarse-grained charnockite and migmatitic felsic gneiss. Textures like K-feldspar micro-veins in migmatitic felsic gneiss, myrmekite-like intergrowth, Th-rich veins in monazite and the presence of pegmatoidal metasomatic rock at the contact of calc-silicate granulite and coarse-grained charnockite further point towards the presence of an additional fluid phase which was capable to transfer elements in micro- to mesoscopic-scale. In the present study such fluid phase is interpreted to be brine which escaped from the rock record perhaps due to its greater mobility. Phulbani domain is characterized by five phases of deformations (D1-D5) and related fabric developments (S1-S5S). Of these, the S1 fabric is found only as inclusion within porphyroblastic phases of aluminous granulite and migmatitic felsic gneiss and produced during D1. Being common in the aluminous granulite, calc-silicate granulite, migmatitic felsic gneiss and fine-grained charnockite gneiss, the S2/S3 gneissic fabric is interpreted to be the earliest recognizable planar fabric of the study area and resulted by successive D2-D3 deformations during UHT metamorphism. The S2/S3 gneissic fabric was transposed during D4 to form S4 and S4S fabrics which dominantly occur parallel to the axial plane of the folded S2/S3 fabric. The S4 fabric later on folded during D5 to form mylonitic fabric (S5S) of the Ranipathar shear zone. Pseudotachylite veins are always associated with this S5S fabric and dominantly occur parallel to this fabric. Outcrop-scale sheath folds also developed during ductile shearing in the Ranipathar shear zone and played a critical role during exhumation of the high-grade rocks of the Phulbani domain. Microstructural investigation of quartz grains of the migmatitic felsic gneiss showing the S4S fabric suggest dominant deformation by prism and rhomb slips. Quartz ribbons in the S5S mylonitic foliation suggest deformation by prism slip in the quartz grains. Microstructures in pseudotachylite veins of the Ranipathar shear zone indicate its origin by melt crystallization following development of mylonititic foliation. Deformed pseudotachylite matrix suggests at least one stage of deformation after pseudotachylite formation during reactivation of the RSZ. Zircon U-Pb (SHRIMP) and monazite U-Th-total Pb (EPMA) analyses obtained in the present study additionally put precise time constraints on the tectonothermal evolution of the Phulbani domain. Zircon from the coarse-grained charnockite shows crystallization age of ca. 970 Ma. Aluminous granulite possibly suffered UHT metamorphism at ca. 987 Ma as revealed from monazite included in porphyroblastic garnet. Monazite in the aluminous granulite and the migmatitic felsic gneiss grew dominantly at 966 ± 4 Ma and 968 ± 4 Ma ages respectively, which are interpreted as the cooling ages subsequent to the peak metamorphism. Oscillatory-zoned zircon grains of the felsic augen gneiss yield ca. 1173 Ma age which is interpreted as the crystallization age of the granitic protolith. This ca. 1173 Ma age granite possibly composed a part of the Proterozoic basement of the Eastern Ghats Province. Monazite age of ca. 781 Ma from aluminous granulite exposed at the N-S trending ductile shear zone and dates within the range of ca. 558–535 Ma from felsic augen gneiss exposed at the RSZ indicate localized shear-induced thermal process in the Phulbani domain. The presently studied rock suite thus recorded four distinct events (ca. 1173 Ma, ca. 1000–900 Ma ca. 781 Ma and ca. 558–535 Ma) of magmatism, metamorphism and deformation of the Eastern Ghats Belt. The tectonometamorphic and tectonothermal histories of the Phulbani domain during the time-frame of 1000–900 Ma appear to be similar if compared with the adjacent Visakhapatnam domain which argues against the domain-based classification of the Eastern Ghats Belt. Based on this, it is inferred that the shear zones marking the boundaries of the domains possibly formed during latter time and cannot be considered as domain boundaries. The metamorphic and the magmatic histories during the time-frame mentioned above additionally matches well with the Rayner complex of the East Antarctica indicating the contiguous nature of these terranes during the inferred ca. 950-900 Ma Rayner-Eastern Ghats orogeny.Item Sedimentological Analyses, Internal Stratigraphy and Sediment hosted Detrital Iron and Radioactive Ore Mineral Potential of the Mesoarchean Siliciclastic Succession around Keonjhar, Singhbhum Craton, Odisha, IndiaMukhopadhyay, JoydipThe 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.Item Tectono metamorphic and geochronological evolution of the Rengali Province in the Riamal Rengali Khamar sector Odisha IndiaBose, SankarRengali 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.Item Petrology of Mafic Ultramafic Rocks around Bangriposi and Kuliana Orissa Eastern India Implications for Paleotectonic settingRay, ArijitThe eastern margin of the Paleoarchean Singhbhum Craton of eastern Indian hosts a number of mafic-ultramafic rock suites. Among them, this research work has been focused on a unique group of mafic-ultramafic rocks, found within polydeformed, metasedimentary North Singhbhum Mobile Belt assemblage, in proximity of the Bangriposi Shear Zone. Two dismembered rock units has been identified in the area of study- (i) a layered gabbroic body near the town of Kuliana (Orissa state), and (ii) a serpentinized wehrlite body near the town of Bangriposi (Orissa state). The gabbroic rocks are found within multiply deformed and folded Banded Magnetite Quartzite rocks, and the N-S trending, elongated wehrlite body is found within high-grade (Kyanite±Staurolite±Chloritoid bearing) schistose rocks. No evidence of emplacement in a liquid state (contact metamorphism, country rock xenoliths, apophytic tongues, chilled margins, feeder dykes etc.) has been found in either of the rock units. The gabbro unit of Kuliana shows excellent mineral laminations in the field and its modal layering is defined by variable abundance of plagioclase, orthopyroxene and clinopyroxene. Crystal Size Distribution analysis of plagioclase grains has identified the involvement of textural coarsening mechanism in textural evolution of these rocks. Their crystallization history was controlled by the transitional interplay between adcumulus growth and textural coarsening mechanism. The internal differentiation and chemical evolution was punctuated by an event of magma chamber replenishment. The wehrlite rocks of Bangriposi contain serpentinized olivine, clinopyroxene, orthopyroxene, Cr-spinel, phlogopite, apatite and numerous accessory minerals formed during serpentinization. Their petrographical and mineralogical characteristics indicate a deeper level metasomatic episode, apart from the shallow level serpentinization event. Reaction textures defined by secondary clinopyroxene, phlogopite, orthopyroxene and occurrence of secondary apatite constitute modal metasomatic effects, whereas elevated LREE contents in whole rocks and clinopyroxene REE patterns constitute the effects of cryptic metasomatism. The gabbroic rocks, representing a fragment of the original static magma chamber in which they formed, display affinities towards gabbroic rocks from oceanic crustal magma chambers in terms of major, trace and clinopyroxene chemistry. Trace elemental composition of melts in equilibrium with these gabbroic rocks were modelled using the Equilibrium Distribution Method. These calculated equilibrium melts have enriched MORB characteristics and the residual melts of the gabbroic rocks share similarities with volcanic rocks from Supra Subduction Zone ophiolites. Their pressure-temperature calculation has yielded conditions of approximately 990 °C and 1.3 GPa. The detailed mineralogical and geochemical study of the wehrlite rocks has revealed a complex picture of the deeper level metasomatic episode and identified the possible infiltrating melt as an alkali- carbonatite. Relict clinopyroxene grains (Cr-diopside) from these rocks show affinities towards mantle clinopyroxenes in terms of mineral chemistry. These grains also yield ~ 1100 °C as the lower limit of temperature, and ~ 3.5 GPa as the upper limits of pressure. Protolith reconstruction of the wehrlite rocks shows that prior to the deeper level metasomatic episode, the original lithology was possibly a depleted MORB type mantle unit. Finally, to establish the genetic link between these individual dismembered mafic ultramafic units a two-stage petrological modelling involving selected immobile elements has been implemented. The results show that ~ 35% partial melting of the wehrlite rocks produced basaltic melts, which subsequently underwent ~ 30% fractionation of early formed olivine, pyroxene, plagioclase and spinel to generate melts which are compositionally identical to the equilibrium melts of the layered gabbroic rocks. The major implication of this inference is that the gabbro and wehrlite rocks are co-genetic and they represent fragments of the central part and the underlying lithospheric mantle of the original oceanic magma chamber respectively. These oceanic crustal and mantle fragments found within mobile belt assemblage near a high-strain zone in the eastern margin of Singhbhum Craton, serve as evidence for a tectonic event involving closure of an ocean basin. It is hoped that with further isotopic and geochronological studies, more details of this event can be obtained and regional and global implications explored.Item Stratigraphy and Nature of uranium mineralization from Precambrian Basement Granitoid -Srisailam Formation contact around Chitrial area, Cuddapah Basin, TelanganaGhosh, Gautam; Bose, SankarThe biotite rich granitoid rocks exposed around Chitrial village varies in character from a porphyritic to massive granite to gneiss or mylonite with characteristic foliations defined by alternate quartzo-feldspathic and biotite rich layers in the latter units. It is intruded by ca. 1.9-1.8 Ga age mafic dyke sets and is overlain by Mesoproterozoic Srisailam Formation rocks of the Cuddapah Supergroup represented by an arenaceous gritty or pebbly sandstone interspersed with thin shale and siltstone horizons. The granitoid locally becomes uranium-rich near its contact with the overlying Srisailam Formation rocks. The present work encompasses stratigraphic, petrological, geochemical and geochronological analyses of the granitoids and accompanying supracrustals with special emphasis on nature and localization of uranium mineralization. Major element geochemical data characterize the granitoid rocks as monzogranites and alkali feldspar granite and the cover rocks as quartz arenites. The trace and rare earth element data were used to identify the protolith history of the granitoid rocks as well as about the nature of provenance of the cover sediments. The geochemical data further provide clues regarding probable tectonic and geodynamic setting of these rocks. A marked enrichment in U, Th and REE (particularly LREE) content of the granitoids has been noted. The overall REE pattern suggests a similar source for all the granitoid types. Several tectonic discrimination diagrams suggest a volcanic arc tectonic setting for these rocks. The recycled mature quartzose cover rocks show distinctly similar geochemical characteristics as the granitoids suggesting a granitoid/felsic source of mature continental provenance. REE patterns of the basement granite and the cover sandstone show similar variation which represents that the derivation of the sediments could be from the underlying basement granite. Recent exploration programme by Atomic Minerals Directorate for Exploration and Research (AMDER) has led to the discovery of a number of potential radioactive mineralized zones in the northwestern part of the Cuddapah basin such as around the Chitrial area. Uranium bearing minerals are intimately associated with sulphide rich minerals within the basement granitoids of the area. There is ample evidence of hydrothermal activity straddling across the unconformity surface which includes- (1) development of fracture filling veins of various dimensions comprising quartz, quartz-epidote, quartz-chlorite or pyrite, (2) hydrothermal alteration of granitoids adjacent to these veins resulting in chloritization and sericitization and (3) epigenetic uranium mineralization in micro-fractures and inter-granular spaces within granitoids. Evidence of uranium mineralization within the cover rocks is comparatively less. In the uraniferous zones in granitoid and overlying quartzite, pitchblende and coffinite are the main uranium phases occurring in micro-fractures and inter-granular spaces of host rock, often in association with pyrite. Depending upon micro-textural data, the paragenetic history of the mineralization has been divided into seven stages in the present study. U-Pb zircon radiometric dating of the basement granitoids reveals that the main tectonothermal event took place in Chitrial area between ca. 2535 Ma and 2519 Ma. Granitoid samples including the grey massive variety, pink granite, granite gneiss, foliated granite and alkali feldspar granite show emplacement ages of 2525±20 Ma, 2519±12 Ma, 2524±18 Ma, 2514±22 Ma and 2524±20 Ma respectively. Hence, it can be concluded that major tectonothermal event affected these rocks of the study area around 2535 to 2514 Ma. Probability density plot of weighted mean ages for the sample CT206 (granite gneiss) shows a strong peak at ca. 2465 Ma while the sample CT207 (foliated granite) shows another strong peak at ca. 2455 Ma which may be related to a second phase of tectonothermal event. U-Pb zircon detrital age of the cover rocks of the Chitrial area gives major cluster ages at ca. 2468 and 2488 Ma that may be correlated with this second tectonothermal event. From these rocks, diagnostic detrital zircons show age peaks at ca. 2520 Ma, 3000 Ma and 3200 Ma, which correspond to the established emplacement ages of the basement granitoid plutons in the Eastern Dharwar Craton. Younger dates are discordant with a lower intercept ages of near 200 Ma in the Wetherill concordia. Older zircon cores with spot data ranging from 2636±28 Ma to 3200±7 Ma are interpreted as grains inherited from the crustal source region or from the wall-rock of the granite intrusion. From the detrital zircon data, it can be inferred that source of the sediments is proximal. EPMA chemical dates of uraninites from the drill core sample 226B shows that the area underwent several episodes of hydrothermal activity, which have left their imprints on the isotope systematics of uraninite. Thus the younger ages furnished by U-Pb zircon radiometric dating of uranium rich in-situ zircon grains of the granite drill core sample (289Av) shows a group age of 172 Ma, possibly related to the much younger tectonothermal event. From this study, it is concluded that the Chitrial granitoids are ‘S’ type in character and formed by intracrustal melting of the deeply buried clastic sediments and subsequent incubational heating. It also implies crustal recycling could be the likely mechanism for granite magmatism during ca. 2535-2514 Ma. Uranium mineralization in the granite was influenced by increased fracture volume in the rocks and was controlled by oxygen fugacity in the ore-bearing hydrothermal fluid. This mineralization is related with the later stage fracture reactivation of the Eastern Dharwar Craton during a major younger tectonic activity.