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This study focuses on marine sediments of the late Paleocene-early Eocene (∼55.5–49 Ma) interval from the Jaisalmer Basin of western India. It demarcates the Paleocene Eocene Thermal Maximum (PETM) using foraminiferal biostratigraphy and carbon isotope stratigraphy. A negative carbon isotope excursion of 4.5‰ delineates the PETM within the basin. We demarcate five foraminiferal biofacies using the detrended correspondence analysis. These reflect characteristics of ecology, bathymetry, relative age, and environment of deposition of the foraminifera. They record the response of foraminifera to the warmth of the PETM. Biofacies A was deposited within an inner neritic setting ∼55.5 Ma and includes benthic foraminifera Haplophragmoides spp., Ammobaculites spp., and Lenticulina spp. The presence of Pulsiphonina prima and Valvulineria scorbiculata in Biofacies B suggests an increase in runoff conditions in the basin. Fluctuating trophic conditions prevailed between ∼54–50 Ma. It is evidenced by alternating Biofacies C (endobenthic and chiloguembelinids of eutrophic conditions) and Biofacies D (epibenthic and acarininids of oligotrophic conditions). Biofacies E is dominated by deep-dwelling parasubbotinids, indicating an increase in bathymetry, possibly corresponding to the Early Eocene Climatic Optimum (∼49 Ma).

Detrital zircon and monazite dating of clastic rocks in the Mesozoic Kutch Basin at the western continental margin of India reveals predominant sediment derivation from rocks of Neoproterozoic Pan-African orogeny, followed by those of Cambro-Ordovician Bhimphedian (or Kurgiakh) orogeny and 850–1000 Ma rocks, with subordinate input from rocks of 700–800 Ma, 1500–1600 Ma, 2400–2500 Ma and 2800–3300 Ma. This finding refutes the existing idea regarding the predominant Mesoproterozoic source inferred for this basin. The dominance of southwesterly palaeocurrent data of Mesozoic rocks in Kutch Basin rules out sediment supply from south or west. Th/U ratios of detrital zircon grains indicate predominantly magmatic and subordinately metamorphic source rock. Petrographic data, particularly the QFR plot supports this interpretation of source rock. Rocks belonging to the Pan-African orogeny are poorly exposed in northwestern India while isolated outcrops of peralkaline granites in the Himalayan region bear testimony of the Bhimphedian orogeny. While the paucity of records of the Pan-African orogeny in western India possibly relates to either burial under the Deccan Flood Basalts or extensive erosion during Mesozoic greenhouse climate, the dearth of rocks of Bhimphedian orogeny results from its occurrence along the present-day Himalayan thrust belt. The absence of detrital zircon grains younger than 458 Ma indicates that post-Ordovician tectono-thermal events skipped the source area. The large gap between youngest detrital zircon and the depositional age of the Mesozoic sediments, suggests long-distance sediment transport as well as sediment recycling. This study, therefore, indicates the existence of widespread younger magmatic rocks to the north during the deposition of Mesozoic of Kutch.

The present paper deals with the memory response on thermal disturbances emanating from a cylindrical cavity in an unbounded thermoelastic solid. Here we have theoretically demonstrated the memory response of thermal disturbances in the generalized magneto-thermo-elastic materials. Firstly, the characteristics of thermoelastic disturbances originated from the cavity in an unbounded elastic solid under the light of generalized magnetothermoelasticity theory with memory dependent derivatives (MDD). For numerical computation, cylindrical-polar coordinate system with radial symmetry subjected to two different types of heat sources into the cavity are considered. An integral transform method and, while in inverse transformation, an efficient and pragmatic NILT (Numerical Inverse Laplace Transform) is adopted. Finally, parameter studies are performed to evaluate the effect of the kernel function and time delay. For thermal wave the results show appreciable differences with those in the usual magneto-thermoelasticity theory.

This study presents a combined petrographical and geochemical investigation to track the compositional changes in the Mesozoic sedimentary record during the evolution of the pericratonic rift basin of Kutch. The Mesozoic sequence of the proven petroliferous basin of Kutch, representing ~3000 m thick siliciclastic and carbonate deposition within a time frame of ~70 Ma, consists of Jhurio, Jhumara, Jhuran and Bhuj formations in ascending order of succession. The dominance of arkosic sandstones and the abundance of zircon and monazite indicate predominantly felsic source rocks. The concentration of individual trace elements such as Th, Sc, Zr, V, Ni and ratios like Th/Sc, Cr/V, Y/Ni, Th/Co, La/Sc support the predominantly felsic source rock. The LREE enrichment and the negative Eu anomaly corroborate the predominantly felsic source. However, concentrations of V, Ni and Ti reveal the mafic input in older stratigraphic units. While (GdN/YbN) indicates dominant post-Archean source across the Mesozoic succession, younger stratigraphic units reveal contributions from the Archean rocks, from Nagar Parkar and Aravalli highland regions. The CIA values suggest intermediate to intense weathering, while the ICV data record a shift from immature sediments in the older formations to mature and recycled types in the younger formations. The high value of Zr/Sc as well a high content of Hf reflects the addition of zircon by recycling or by erosional unroofing of older continental rocks. Major oxide (SiO2, Na2O and K2O) and trace elements (La, Th and Hf) bear the passive margin setting for the Kutch Basin during the Mesozoic. The decrease in feldspar content (in sandstones), increase in the concentration of Zr and Hf (in shale) and a decrease in values of ICV from older to younger stratigraphic units corresponds to the compositional evolution related to increased stability of the Kutch basin during the transition from early syn-rift to post-rift.

This study presents a detailed crystallo-chemical characterization of glauconites occurring at different stratigraphic intervals within the phosphorite-bearing Campanian Duwi Formation. While authigenic glauconites occur within the shallow marine, transgressive deposits of Abu Tartur Phosphate and Maghrabi Shale Members in the Campanian Duwi Formation, allogenic variety occurs within the regressive deposits at the top of the Liffiya Shale Member. Nascent to slightly evolved, shallow-marine originated authigenic glauconites are distinct by a high content of MgO. A good correlation between K2O and Fe2O3(total) contents of glauconites in the Maghrabi Shale supports ‘layer lattice’ theory while a combination of ‘layer lattice’ and ‘verdissement’ theories explain the origin of other glauconites within the Duwi Formation. X-Ray Diffraction studies reveal a ‘true’ di-octahedral nature and 1M ordering of the glauconite pellets with smectite inter-stratification. Mossbauer spectroscopic study reveals Fe3+ as the dominant cation in the octahedral site that preferentially occupies the less distorted cis M(2) sites. Glauconites acquire a high Mg-content because of the passage of Mg- and Ca-rich fluid that leads to extensive dolomitization. Glauconites form at the transition zone between black shale and phosphate, representing oxygen-depleted conditions. Similar shallow marine glauconites occur all along the paleo-Tethyan margin during the Late Cretaceous time.

Microstructural and surface characterization of Ni-based alloys viz. Alloy 690, Alloy 693 and Ni-17 wt.% Mo- 7wt.% Cr exposed to molten FLiNaK salt under air atmosphere at 973 K was carried out. Patches of mixed oxide layers of type NiO + Cr2O3, NiO + Al2O3 +Cr2O3 and MoO3 + NiO + Cr2O3 were observed for Alloy 690, alloy 693 and Ni-Mo-Cr alloy, respectively. Corrosion susceptibility index and calculated Cr diffusivity in the alloys followed the order: Alloy 690 > Alloy 693>Ni-Cr-Mo alloy. The oxide layers developed are only partially protective as they form a galvanic micro-couple with exposed surface which makes the later more prone to attack. The lower Cr depletion in case of Ni-Mo-Cr alloy as compared to Alloy 690 and 693 can be attributed to the fact that MoO3 layer is formed over the areas devoid of oxide patches which may prevent/reduce galvanic coupling between Ni-,Cr-rich oxides and exposed surface.

An integrated study involving petrographical, mineralogical and geochemical investigations proposes the origin of the Bakchar ironstone deposit by upward migration of a mixture of Fe-rich brine and hydrothermal fluid through marine sediments. Trace element concentrations of the ironstone deposits rule out continental derivation of Fe, while high REE concentrations indicate mixed hydrogeneous and hydrothermal source. Three main types of ironstone within the Bakchar deposit are characterized by distinct mineralogical assemblage of authigenic minerals corresponding to oxic, methanic and weakly sulfidic dysoxic conditions. Changing redox conditions of the depositional environment, methane seepage in warm seawater and availability of iron influx possibly determined the final mineralogy of three varieties of ironstones. The association of siderite with ferrimagnetic sulfides like greigite and pyrrhotite in type-1 ore indicate anaerobic oxidation of methane with limited bacterial sulfate reduction. The ironstone deposits of Narym, Kolpashevo and Bakchar are contemporaneous with geological events like ocean anoxic event 3 (OAE-3), Cretaceous-Paleogene (K-Pg) boundary and Palaeocene-Eocene Thermal Maximum (PETM), respectively, all corresponding to warm seawater conditions.

An integrated petrographical, geochemical, and mineralogical investigation reveals the wide variation in the mineral chemical composition of glauconites within the Albian-Cenomanian Aitamir Formation. Bounded between a black shale (Sanganeh Formation) below and chalky limestone (Abderaz Formation) above the Aitamir Formation represents an inner shelf deposit. Glauconite may occur either as pellets or as altered zones within feldspar and mica. Poor sorting and deeply penetrative crack indicate the authigenic nature of glauconite pellets. The contents of Fe2O3, MgO, Al2O3, and SiO2 of glauconites vary widely while the K2O exhibits a limited spread indicating the evolved nature of the glauconite. The glauconite matures at a fixed and high value of K2O with variable Fe2O3 (total) supporting the replacement origin. The X-ray diffraction study reveals a negligible interstratification within glauconites. The micro-textural study attests to the highly evolved nature of the glauconite. The shallow marine glauconite within the Albian-Cenomanian Aitamir Formation formed under sub-oxic, shallow depositional setting during the middle Cretaceous global warming phase within the Tethyan domain.

Although Paleogene warm climatic intervals have received considerable attention for atmospheric and oceanographic changes, the authigenic mineralization associated with these time spans remains overlooked. An extensive review of the literature reveals a close correspondence between the high abundance of glauconite and warm climatic intervals during the Paleogene period. The abundance of phosphorite, ironstone, lignite and black shale deposits reveals similar trends. Although investigated thoroughly, the origin of these authigenic deposits is never understood in the background of Paleogene warming climatic intervals. A combination of factors like warm seawater, hypoxic shelf, low rate of sedimentation, and enhanced rate of continental weathering facilitated the glauconitization. The last factor caused the excess supply of nutrients, including Fe, Si, K, Mg and Al through the rivers, the cations needed for the formation of glauconite. The excessive inflow of nutrient-rich freshwater into the shallow seas further ensured high organic productivity and stratification in shallow shelves, causing hypoxia. The consequent rapid rise in sea-level during the warm periods created extensive low-relief shallow marine shelves starved in sediments. Oxygen-deficiency in the shallow marine environment facilitated the fixation of Fe into the glauconite structure. The inflow of nutrient-rich water during the warm climatic intervals facilitated the formation of phosphorite, ironstone, and organic-matter-rich sedimentary deposits as well. Although global factors primarily controlled the formation of these authigenic deposits, local factors played significant roles in some of the deposits. Therefore, phosphorites formed in marine conditions with open circulation within the tropical zone. While lush growth of rainforest covers in the tropical belt facilitated the formation of coastal lignite.

A combined facies, petrography and isotope geochemistry reveal an extensive pedogenic alteration of platform carbonate deposits of the Upper Cretaceous Bagh Group in the western Narmada basin in central India. The highly fossiliferous carbonate sequence of the Bagh Group consists of two formations, the Nodular Limestone at the base, and the Bryozoan Limestone Formation at top. The Nodular Limestone Formation comprises primarily of mudstone and wackestone, with relics of bioclasts such as gastropods, echinoderms, molluscs, forams and calcispheres, reflecting a low-energy supratidal to upper intertidal environment of deposition. Prolonged pedogenesis leads to pervasive micritization, brecciation, desiccation and recrystallization. The overlying Bryozoan Limestone, dominated by packstone and planar laminated rudstone with bryozoans, gastropods, echinoderms/echinoid spines, and molluscs, indicates deposition within the lower intertidal environment with moderately high-energy conditions. Abundant meniscus cement and biomolds suggest meteoric vadose diagenetic modification, whereas, intense secondary micritization of sediments indicates prolonged calichification. The δ13C and δ18O ratios of both Nodular Limestone and Bryozoan Limestone formations are depleted than the normal marine values, indicating an extensive diagenetic resetting of the carbonates. While the meteoric cement is depleted in both δ13C and δ18O ratio, the burial cement shows a decrease of δ18O at constant δ13C. The pedogenetic horizons within the Bagh carbonates bear subtle evidence of subaerial exposures within the overall transgressive Bagh Group. A glauconite bed at the upper part of the Bryozoan Limestone Formation marks the top part of the transgressive deposit.

This study presents major element, radioactive element and rare earth element (REE) concentrations of the Garampeta to Markandi beach along the southern coast of Odisha, India to delineate the source signature and resource potential of the beach placer deposits. Average ∑REE concentration of the beach sand samples is about four times higher than the average crustal concentration. The LREE concentration is higher than HREE, with a pronounced negative europium anomaly. The study also discusses about the radioelement 238U, 232Th and 40K concentrations in the study area, and their relationship with REE. Weathering condition of the source rock, based on the major elements and Th/U ratio indicated a reasonably high degree of weathering. Major element and the REE composition along with the europium anomaly, relate the beach placers to mainly charnockite and khondalite source. An elevated level of thorium (> 60 times than the average UCC values) as exhibited by the samples could be attributed due to the presence of monazites. The high concentration of REEs like Nd and Dy along with La and Ce indicates significant REE resource potential in the beach placers which is important for the resource potential in terms of the strategic mineral reserves of the country.

This study explores the fertilizer potential of glauconitic soil by monitoring its impact on the growth of plants during the second growing season after application. Our study documents a higher growth of oats (Avena sativa) in glauconitic amended soil compared to that recorded with the control sample at the end of a 97-day-long experiment. Concentrations of nutrients (K, P, ammonium, Ca, Mg) and pH of the soil increase sharply in the first growing season and mildly thereafter, after an initial concentration of 200 g&middot, m&minus, 2 glauconite (equivalent to 2 t&middot, ha&minus, 1). The pH of the glauconitic-amended soil increases from an initial 6.0 to 6.34 during the second season. Organic matter and nitrates decrease in the soil mixture at the end of the second growing season, while the exchangeable ammonium increases. Organic acids promote the mobility and bioavailability of nutrients in the soil. Glauconitic soil is particularly effective for weakly acidic soils with a low moisture content. The steady increase in total yield and plant height, and the slow-release of nutrients during the second growing season indicates that glauconitic soil can be an effective and eco-friendly fertilizer.

This study focused on uppermost Cretaceous sedimentary rocks deposited in the Himalayan region and around the core of peninsular India just before the eruption of the Deccan Traps. Detailed stratigraphic and sedimentological analysis of Late Cretaceous successions in the Himalayan Range together with literature data from the Kirthar fold-and-thrust belt and central to southeastern India document a marked shallowing-upward depositional trend that took place in the Campanian–Maastrichtian before the Deccan magmatic outburst around the Cretaceous-Tertiary boundary. Topographic uplift of the Indian peninsula began in Campanian time and is held responsible for thick sediment accumulation associated with shorter periods of nondeposition in peripheral areas (Himalayan Range, Kirthar fold belt, and Krishna-Godavari Basin) than in the central part of the Deccan Province. Surface uplift preceding Deccan volcanism took place at warm-humid equatorial latitudes, which may have led to an acceleration of silicate weathering, lowered atmospheric pCO2, and climate cooling starting in the Campanian–Maastrichtian. The radial centrifugal fluvial drainage in India that is still observed today was established at that time.

This study investigates the process of formation of ooidal ironstones in the Upper Cretaceous-Paleogene succession in western Siberia. The formation of such carbonate-based ironstones is a continuing problem in sedimentary geology, and in this study, we use a variety of data and proxies assembled from core samples to develop a model to explain how the ooidal ironstones formed. Research on pyrite framboids and geochemical redox proxies reveals three intervals of oceanic hypoxia during the deposition of marine ooidal ironstones in the Late Cretaceous to the Early Paleogene Bakchar ironstone deposit in western Siberia; the absence of pyrite indicates oxic conditions for the remaining sequence. While goethite formed in oxic depositional condition, chamosite, pyrite and siderite represented hypoxic seawater. Euhedral pyrite crystals form through a series of transition originating from massive aggregate followed by normal and polygonal framboid. Sediments associated with goethite-chamosite ironstones, encompassing hypoxic intervals exhibit positive cerium, negative europium, and negative yttrium anomalies. Mercury anomalies, associated with the initial stages of hypoxia, correlate with global volcanic events. Redox sensitive proxies and ore mineral assemblages of deposits reflect hydrothermal activation. Rifting and global volcanism possibly induced hydrothermal convection in the sedimentary cover of western Siberia, and released iron-rich fluid and methane in coastal and shallow marine environments. This investigation, therefore, reveals a potential geological connection between Large Igneous Provinces (LIPs), marine hypoxia, rifting and the formation of ooidal ironstones in ancient West Siberian Sea.

This paper investigates the provenance of Middle Jurassic to Early Cretaceous sediments in the Kutch Basin, western India, on the basis of mineralogical investigations of sandstones composition (Quartz–Feldspar–Lithic (QFL) fragment), Zircon–Tourmaline–Rutile (ZTR) index, and mineral chemistry of heavy detrital minerals of the framework. The study also examines the compositional variation of the sandstone in relation to the evolution of the Kutch Basin, which originated as a rift basin during the Late Triassic and evolved into a passive margin basin by the end Cretaceous. This study analyzes sandstone samples of Jhumara, Jhuran and Bhuj Formations of Middle Jurassic, Upper Jurassic and Lower Cretaceous, respectively, in the Kutch Mainland. Sandstones record a compositional evolution from arkosic to subarkosic as the feldspar content decreases from 68% in the Jhumara Formation to 27% in the Bhuj Formation with intermediate values in the Jhuran Formation. The QFL modal composition indicates basement uplifted and transitional continental settings at source. Heavy mineral content of these sandstones reveals the occurrence of zircon, tourmaline, rutile, garnet, apatite, monazite and opaque minerals. Sub-rounded to well-rounded zircon grains indicate a polycyclic origin. ZTR indices for samples in Jhumara, Jhuran and Bhuj Formations are 25%, 30% and 50% respectively. Chemistry of opaque minerals reveals the occurrence of detrital varieties such as ilmenite, rutile, hematite/magnetite and pyrite, in a decreasing order of abundances. Chemistry of ilmenites in the Jhumara Formation reveals its derivation from dual felsic igneous and metabasic source, while those in Jhuran and Bhuj Formations indicate a metabasic derivation. Chemistry of garnet reveals predominantly Fe-rich (almandine) variety of metabasic origin. X-ray microscopic study provides the percentage of heavy minerals ranging from 3% to 5.26%. QFL detrital modes reflect the evolution of the basin from an active rift to a passive margin basin during the Mesozoic. Integration of results from QFL modal composition of the sandstones, heavy mineral analysis and mineral chemistry, suggests sediment supply from both northern and eastern highlands during the Middle Jurassic. The uplift along the Kutch Mainland Fault in the Early Cretaceous results in curtailment of sediment input from north.

This study presents geochemical characteristics of glauconites in estuarine deposits within the Maastrichtian Lameta Formation in central India. Resting conformably over the Bagh Group, the Lameta Formation consists of ∼4–5 m thick arenaceous, argillaceous and calcareous green sandstones underlying the Deccan Traps. The sandstone is friable, medium- to coarse-grained, well-sorted and thoroughly cross-stratified, and contains marine fossils. Detailed petrography, spectroscopy and mineral chemistry indicates unique chemical composition of glauconite with high K2O, MgO, Al2O3 and moderate TFe2O3. Glauconite is formed by the replacement of K-feldspars, initially as stringers in the cleavages and fractures of feldspars. Incipient glauconite subsequently evolves fully, appearing as pellets. Fully-evolved glauconite pellets often leave tiny relics of K-feldspar. XRD exhibits characteristic peak of 10 Å from basal (001) reflection of glauconite, indicating the “evolved” character. The K2O content of glauconites in the Lameta Formation varies from 5.51% to 8.29%, corroborating the “evolved” to “highly-evolved” maturation stage. The TFe2O3 content of glauconite varies from 12.56% to 18.90%. The PASS-normalized-REE patterns of glauconite exhibit a “hat-shape” confirming the authigenic origin of glauconites. The slightly-negative to slightly-positive Ce anomaly value and the moderate TFe2O3 content of glauconite agree well with a suboxic, estuarine condition. The replacement of K-feldspar by the glauconite contributes towards the high K2O content. Compositional evolution of glauconites in the Lameta Formation is similar to those observed in many Precambrian sedimentary sequences. Keywords: Glauconite, Estuary, Mineral chemistry, Cerium anomaly, Redox condition, Lameta Formation, Narmada Basin

Sandy and muddy detritus from two distinctive end-member provenance terrains, basaltic and granitic, are transported to the estuaries of the Gulf of Khambhat by fluvial discharge and opposing tidal currents making this embayment ideal for investigating the effects of mineralogical and geochemical mixing on sediment composition in estuarine depositional systems. Rivers flowing predominantly from the north over Precambrian metasediments and granites supply a felsic plutoniclastic sand to the gulf, whilst a mafic volcaniclastic sand, sourced by Deccan basalts, is transported by rivers draining the Western Ghats and from the local coastal erosion in the southern part of the gulf. Sediments from the Tapti estuary are rich in basaltic rock fragments (∼50%) and are characterised by a distinctly basaltic source composition (La/Sc∼0.25–0.86, Th/Sc∼0.12–0.40, Cr/Th∼13–121, Eu/Eu*∼0.93–1.68 and LREE/HREE∼2.96–6.57). By contrast, the sediments of the Sabarmati inner estuary are rich in quartz grains (80%) as evident from the major and trace element compositions (La/Sc∼1.38–6.63, Th/Sc∼0.58–2.98, Cr/Th∼0.58–19.39, Eu/Eu*∼0.46–0.86 and LREE/HREE∼2.90–11.40). The detrital compositions of the remaining major estuaries, the Narmada, Dhadhar and Mahi, scatter across a broad range in a QFR diagram and contain varying amounts of quartz, feldspar and rock fragments. In the Narmada Estuary the mixed signature characterised by REE values including Eu/Eu* (∼0.42–2.28) and LREE/HREE (∼4.37–14.80) is caused by the presence of diverse rock types that crop out in the source area. In the Mahi estuary, which largely flows across felsic source terrains the compositional signature is controlled by mixing of felsic detritus from riverine input with mafic sediments from seaward side in the estuary. The two end-member detrital compositions, plutoniclastic and volcaniclastic, are mixed in the macro-tidal estuaries. Mixing of sediment takes place where fluvial currents and tidal flows interact and the proportion of mixing varies systematically from outer to central to inner estuary. A high degree of mixing of felsic sediments with Deccan basalt derived sediments takes place in the outer estuary resulting in felsic:mafic ratios of ∼40:60. Sediments in the central estuaries (∼65:35) and in the fluvial-dominated inner estuaries (∼90:10) are characterised by moderate to minor degrees of mixing. The mixing in estuaries is systematic and is reflected in both the mineralogy and geochemistry of the sediments. Provenances of ancient estuarine successions should therefore be interpreted with great care incorporating awareness of the mixing processes which influence sediment compositions to different degrees in estuaries, especially those characterised by strong tidal currents.

The time varying currents in the Ohmic transformer in the SST-1 tokamak induce voltages that drive large eddy currents in the passive structures like the vacuum vessel and cryostat. Since the vacuum vessel and the cryostat are toroidally continuous without electrical breaks in SST- 1, this leads to a shielding effect on the flux penetrating the vacuum vessel. This reduces the magnitude of the loop voltage seen by the plasma as also delays its buildup. Also the induced currents alter the null location of magnetic field. This will have serious implications on the plasma breakdown and startup and corrective measures may be required in case of an insufficient loop voltage or an improper null. Further, the eddy currents distribution will be vital for the plasma equilibrium and need to be considered while reconstructing the equilibrium. Evolution of the toroidal eddy currents in SST-1 passive structures has been studied using a toroidal-filament model. The model calculations are compared with the measured signals in the magnetic diagnostics like the toroidal flux loops and magnetic pick-up coils installed on the SST-1., Comment: 21 pages, 16 figures

Middle Eocene Fulra Limestone and Oligocene Maniyara Fort Formation represent platform carbonate deposits of Kutch at the north-western margin of India. These carbonates contain larger benthic foraminifera, including Alveolina, Assilina, Discocyclina, Lepidocyclina, Miogypsina, Nummulites and Spiroclypeus. This study presents paleodepositional and paleobathymetric interpretations for both formations using benthic foraminifera in combination with lithological association, sedimentary structures and early diagenetic features. The six carbonate facies comprising the Fulra Limestone indicate a depositional spectrum ranging from bar-lagoon to mid-ramp depositional conditions. It records several shallowing upward cycles, leading to emergence and formation of paleokarst. The four carbonate facies of the Maniyara Fort Formation represents deposition within the inner ramp setting in bar-lagoon and patch-reef environment, while intervening fine siliciclastics correspond to episodes of relative sea level fall. Nummulitic accumulations form low-relief bars within the fair weather wave base in both the formations. The depositional setting of the Paleogene carbonate in Kutch broadly resembles Eocene platformal deposits in the circum-Tethys belt.

This paper explores suitability of glauconitic rocks in the Upper Cretaceous Bakchar deposit in Western Siberia as alternate potash fertilizer. The K 2 O content of these glauconitic rocks varies from 2.5 to 4.1 wt.%, indicating their good potential as K-fertilizer for agronomic uses. According to the different compositional and textural characteristics, glauconitic rocks can be divided into three types, i.e., glauconitolite, glauconitic sandstone and glauconite-chamosite ooidal ironstone, with glauconite concentrations 58.5 wt.%, 25.7 wt.% and 24.6 wt.%, respectively. The intermediate size fraction of glauconitolite concentrates up to 90.4 wt.% of glauconite grains by using wet sieving. Magnetic separation further increases the concentration of glauconite grains for each type of rock samples, especially of glauconitic sandstone. Mixing of glauconitic products with soil increases the germination rate of oat seeds by up to 5.2%, the seedling height records an increase from 0.8% to 18.8%. Both untreated glauconitolite and its granulometric fraction result same rate of growth of oat seedlings. The results of this study suggest that the Bakchar glauconitic deposit can be used as a substitute potash fertilizer, with or without sieving and magnetic separation.

Biological and ecological changes across the Paleogene hyperthermal events were accompanied by dramatic shifts in sedimentation systems in both marine and continental environments. This study investigates the formation of authigenic glauconite within a biostratigraphically constrained section encompassing the Paleocene-Eocene Thermal Maximum (PETM). Paleogene transgressive shelf deposits in the Jaisalmer Basin in western India are represented by the Khuiala Formation, consisting of grey shale, limestone, and glauconitic shale. Foraminiferal assemblage not only constrains the age of the glauconitic shale to planktic zone E1 but also indicates the deposition of sediments in an oxygen-depleted mid-shelf environment. A detailed geochemical and mineralogical characterization of the authigenic glauconite within the mid-shelf deposits reveals the highest glauconite content within the maximum flooding zone, immediately below the negative carbon isotope excursion representing the PETM, followed by its steady decrease. The geochemical signature of the glauconite is unusual for its high Al2O3 and MgO and medium Fe2O3 and SiO2 contents. The K2O content suggests the ‘evolved’ nature of the glauconite, which is confirmed by the X-ray diffractional parameters and the presence of the ‘rosette’ texture in FEG-SEM images. The glauconite evolved by Al-for-Fe substitution in the octahedral site and subsequent fixation of K+ into the interlayer sites. The high alumina content of the glauconite corresponds to the high Al3+ in the tetrahedral layer, inherited from an aluminous substrate. Mossbauer spectroscopy suggests the dominance of Fe3+ compared to Fe2+ in the octahedral site of glauconite pellets. The unusual variety of glauconite formed by the transformation of continent-derived kaolinite and iron oxide in oxygen-depleted porewater conditions. Glauconite authigenesis in the Khuiala Formation is strongly influenced by the warm climatic condition, oxygen-depletion in the mid-shelf environment, and sharp marine transgression promoting sediment starvation associated with the PETM.

This study documents the effects of igneous dike intrusion on organic geochemical parameters of a shallow marine originated, Late Jurassic black shale (av. TOC = 2.2 wt%) in the Kutch rift basin in western India. The dike intrusion forms extremely to mildly altered, meter-scale zones around them. The primary wrinkled micro texture of the shale is lost completely, and organic matter is charcoalized in the extremely altered zone recording a Rock-Eval T-max > 458 degrees C. Immature type-III kerogen dominating the unaltered shale records abundant coniferal biomarkers such as retene, ent-beyerane, phyllocladane, ent-kaurane, abietane, labdane and norisopimarane, besides n-alkanes, hopanes and steranes. The transition from the unaltered (Rock-Eval T-max < 432 C) to the altered zone involves a decrease in carbon preference index (CPI), pristane/n-C-17, phytane/n-C-18, C-30 hopane/C-29 alpha alpha alpha-sterane and gradual increase in C-29 diasterane/sterane, trisnorneohopane/trisnorhopane (Ts/Tm), Ts/C-30 hopane, C-29/C-30 hopane and C-29 20S/(20S + 20R) sterane ratios. Although most saturate biomarkers disappear in the extremely altered zone, it records a high abundance of thermogenic polycyclic aromatic hydrocarbons (PAHs), commonly found in palaeo-fire deposits. Besides the PAH ratios, methylphenanthrene index-1, pristane/phytane, CPI and C-29/C-30 hopane ratios are found to be influenced significantly by thermal maturation in the extremely altered zone. The fluoranthene/(fluoranthene + pyrene) ratio correctly distinguishes different intensities of combustion products, while other PAH ratios behave differently at the immediate contact of the dike. Pr/Ph ratio may correctly interpret the redox condition up to a Rock-Eval T-max similar to 520 degrees C, while it is ineffective at high maturity. The results of the investigation are significant for the assessment of stability of biomarkers in highly matured source rocks, recording potential redox-sensitive biomarkers in highly matured shales and detection of palaeo-fire deposits in ancient sedimentary succession.

An integrated study involving sedimentology, mineral chemistry and spectroscopy highlights a distinctive compositional evolution of Cretaceous glauconite within the Ukra Hill Member. Glauconite occurs at the top part of transgressive systems tract deposits built on a marine shelf. The concentration of glauconite steadily increases towards the maximum flooding surface, maximizing around 50%, and sharply falls at the onset of progradation. Unlike most Phanerozoic examples, Ukra glauconite forms by the variable degree of replacement of quartz, feldspar and mica grains. XRD, FEG-SEM and spectroscopy of glauconite pellets indicate an 'evolved' stage of maturation. Mossbauer spectroscopy reflects a minor substitution of Al3+-Fe3+ (total) in tetrahedral sites and significant substitution of the same in octahedral sites. A consistently high value of 1(20 as well as Fe2O3 contradicts the two popular theories, 'layer lattice' and 'verdissement', and support replacement origin of glauconite in a high a(si+) and high a(K+) pore water environment. Incipiently formed glauconite records a marginal increase in K2O content accompanied by release of Al2O3 and SiO2 to form evolved glauconite pellets; those forming within quartz grains involve an addition of Fe2O3 (total) content during maturation. The minimal increase in K2O content of incipiently formed glauconite, best exhibited by those formed within quartz grains is possibly related to stratigraphic condensation. Compositional evolution like this is exhibited by Precambrian glauconites involving abiotic substrates, but is unusual for the Phanerozoic. Original K2O and Fe2O3 (total) content of glauconites is reduced around peripheries and fractures during diagenesis, adding to compositional variability. (C) 2017 Elsevier Ltd. All rights reserved.

The placement of the boundary between the Lower and the Upper Vindhyan in the Son valley, an unconformity, has long been at the centre of a raging debate. At the Bundelkhand sector, it is placed between the Rohtas Limestone and the Sasaram Sandstone (Lower Quartzite). On the other hand, in the Son valley sector, it is placed between the Bhagwar Shale and the Kaimur Formation. The recent study reveals the existence of ca. 12 m thick sandstone between the Bhagwar Shale and Rohtas Limestone, traced over 150 km in the Son valley sector. Based on in-depth facies constituents and facies tracts, this sandstone is an exact equivalent of the Sasaram Sandstone in the Bundelkhand sector. Its base is strongly erosional and limestone and chert clasts derived from the underlying Rohtas Limestone are abundantly present at the basal part of the sandstone and the unconformity between the Upper and Lower Vindhyan are likely to be present in between.

Various research strategies involving biomarker discovery and mechanistic studies in system biology depend on reproducible and reliable quantification of all metabolites from tissue(s) of interest. Contemporary analytical methods rely on mass spectrometry-based targeted and/or untargeted metabolomics platforms. The robustness of these analyses depends on the cleanliness of the samples, accuracy of the database, resolution of the instrument, and, the most variable of the list, the personal preferences of the researcher and the instrument operator. In this chapter, we introduce a simple method to prepare murine liver samples and carry it through the Isotope Ratio Outlier Analysis (IROA®) pipeline. This pipeline encompasses sample preparation, LC-MS-based peak acquisition, proprietary software-based library creation, normalization, and quantification of metabolites. IROA® offers a unique platform to create and normalize a local library and account for run-to-run variability over years of acquisition using the internal standards (IROA®-IS) and long-term reference standards (IROA®-LTRS).

This paper presents an integrated study aiming to assess the stratigraphy, sedimentology and paleogeography of the marine and non-marine Tellian, Bejaoua and Fortuna Oligo-Miocene deposits of northern Tunisia. The fossiliferous strata, particularly the glauconite-rich facies, bounded by major unconformities, refine the stratigraphic framework and address the spatio-temporal relationship between marine and non-marine deposits. Three new updated paleogeographic maps for the Oligocene (30-27 Ma) and the Miocene (21-20 Ma and 15 Ma) epochs, outlining the major transgressive and regressive events and the relationships between the Tellian and Atlasic basins have been produced. The genesis and evolution of the Oligo-Miocene foreland sub-basins of the Tellian, the salt domes zone and the northern Atlas are reconstructed considering the geodynamic events that accompanied the African-Eurasian convergence, besides eustasy and climate.

Plasma burnthrough and current ramp-up phases in an SST-1 superconducting tokamak are simulated by the OOPS code. The main purpose of this study is to optimize the operation regime in SST-1 through the input parameter scan for OOPS for both successful and failed shots from the SST-1 database. SST-1 is now equipped with carbon plasma facing components (PFCs). Hence, PFCs are expected to offer a carbon dominated impurity environment. An electrically continuous vacuum vessel and cryostat hinder sufficient loop voltage during start-up, thereby rendering electron cyclotron resonance heating (ECRH) pre-ionization an absolute requirement. OOPS simulation is optimized for the essential plasma initiation parameters like the seed electron density ne = 3 × 1017/m3 and the initial neutral density n0 = 1–4 × 1018/m3 (corresponding to a tailored pre-fill pressure) and for an error magnetic field Berr ≤ 20 G. The simulation shows that the ECRH pre-ionization threshold power required for the successful plasma start-up un...

An integrated field, petrographical and geochemical investigation reveals a shallow marine dys-oxic depositional setting for the glauconite at the top of the Mesoproterozoic Lower Quartzite Member of the Vindhyan Supergroup. A thorough facies and paleogeographic analysis indicates a storm-influenced, shallow subtidal depositional condition for the glauconitic sandstone, occupying the mid-level of a transgressive systems tract (TST) deposit, which is capped by the maximum flooding zone (MFZ). The X-ray diffractional parameters confirm the evolved character of the glauconite. The mineral chemical analysis indicates the glauconite is enriched in K2O, MgO and Al2O3 and depleted in Fe2O3(total), compared to the Phanerozoic variety. It formed by the pseudomorphic replacement of the K-feldspar, by the addition of Fe2O3 at consistently high content of K2O, unlike most Phanerozoic examples. The elevated level of H3SiO4, Cl, K, Na, Mg and Fe, possibly derived by the continental weathering and/or contemporary volcanism, facilitated the glauconitization process. The high content of Mg in the glauconite corresponds to the Mg-rich, Mesoproterozoic seawater. A dys-oxic depositional condition, associated with a major marine flooding surface, favoured the formation of glauconite. While the onset of anoxic regime caused the disappearance of glauconite and the deposition of pyritiferous and carbonaceous shale in the overlying condensed zone deposits.

An integrated textural, mineralogical and chemical investigation reveals the origin of authigenic glauconite within the Mesoproterozoic Rabanpalli Formation in the Bhima Basin and its subsequent alteration to chlorite. Glauconite forms within the transgressive shallow shelf deposits in the Rabanpalli Formation. It primarily occurs in two modes, as thoroughly replaced form of detrital grains, and as altered zones along cleavages and fractures of quartz, K-feldspar and mica. All varieties of glauconites exhibit high contents of K2O. The Fe2O3 (T) content is highest in glauconite formed within mica, while it is least in glauconite formed by the replacement of feldspars. Pseudomorphic replacement of substrates by glauconite best explains the origin of glauconite in the Rabanpalli Formation. Diagenetic chlorite, mostly occurring as thick rims on grains and along the grain margin fractures replaces glauconite. Chloritization predominantly takes place in the glauconite variety forming within the mica. The mineral chemistry of chlorite is characterized by high MgO and Fe2O3 (T). Chloritization involves the simultaneous removal of Fe, Mg and Si from the glauconite structure to form brucite type sheets. The high contents of Fe2O3 (T) and MgO, reducing porewater and the high thermal maturation of sediments facilitate the formation of chlorite within the Rabanpalli Formation. This study, therefore, indicates that the rarity of glauconite in the Precambrian is related to its alteration to chlorite.

The Oligocene Maniyara Fort Formation in western India exhibits two distinct glauconite types with different maturation states, which are characterized by their spectral response in the visible to infrared spectrum of electromagnetic radiation. Spectral signatures of Maniyara Fort glauconites display absorption features at approximately 0.77, 1.08, 1.9, 2.3 mu m in the visible-short-wave infrared (SWIR) and 2.8 and 10 mu m in the mid-infrared (MIR) region which vary with 1020 content of glauconite. The spectra of glauconite varies significantly as a function of its cationic contents and substitution in different sites. The maturity is found to increase in tandem with the metal-metal charge transfer (CT) and the Fe2+ dd absorption band respectively at 1.08 and 0.77 pm. H2O and OH- signatures at the NIR region reflect differences in the sensitivity of glauconites with different molecular H2O content. In the MIR region, a gradual shift of the Si-O stretch at 10 m towards lower wavelengths indicates the dominance of smectite layers in glauconites. This study demonstrates a strong correlation between the proportion of expandable layers in the glauconite structure with variations in characteristic band position, depth and symmetry in reflectance and emissivity. (C) 2017 Elsevier B.V. All rights reserved.

The Paleogene sections of Kutch are the reference for the regional chronostratigraphic units of India. The ages of these dominantly shallow marine carbonates are mainly based on larger benthic foraminifera (LBF). The taxonomic revisions of the LBF and the progressively refined shallow benthic zonations (SBZ) have necessitated the present study on updating the stratigraphy of the area. The sedimentation in Kutch commenced with the deposition of volcaniclastics in terrestrial environments in the Paleocene. The marine transgression in SBZ 5/6 deposited finer clastics and carbonates, designated as Naredi Formation, in early Eocene. There is no evidence of marine Paleocene in Kutch. A major hiatus spanning SBZ 12 to SBZ 16 was followed by the development of a carbonate platform and deposition of Harudi Formation – Fulra Limestone during the Bartonian, SBZ 17. The hiatus corresponds to a widespread stratigraphic break in Pakistan and India to Australia, referred as the ‘Lutetian Gap.’ The Maniyara Fort Formation is assigned to SBZ 22 B and SBZ 23, and its age is revised to Chattian. Climate played a major role in building up of the Paleogene stratigraphic succession of Kutch, the carbonates formed during the warming intervals and the stratigraphic gaps were in the intervening cooling periods.

This study examines factors favouring optimal release of potassium from a glauconitic rock by moderate roasting-leaching. Sieving and electromagnetic separation of oolitic iron ore deposit increases the concentration of glauconite grains substantially. Roasting and chemical leaching of this concentrate enhances the release of potassium as interlayer structures of glauconite collapses. This study records the percentage of potassium recovered from glauconite under different experimental conditions, viz., temperature, reaction time, concentration as well as volume of HCl and stages involved in the leaching treatment. Leaching of glauconite without roasting results a low recovery ( < 15%) of K at room temperature. The recovery of K content from the sample increases markedly with increase in concentration of HCl, leaching time, and the ratio by mass of sample to HCl, and marginally with increased stages of leaching. Roasting at 900 degrees C recovers maximum K up to 62-63% for one-stage leaching treatment at 100 degrees C for 120 min with a 4 mol.l(-1) HCl solution for a sample: HCl ratio of 1:5. The roasting-leaching method, therefore, holds promise for converting glauconite to potash salts for agronomic applications.

The sequence architecture and depositional systems of the Palaeogene lacustrine rift succession in the southern steep slope of the Shijiutuo Uplift (SU) in Bohai Offshore Basin (BOB) were investigated using combined 3-D seismic, well log and core data. Four second-order/composite sequences and seven third-order sequences were identified. A detailed analysis revealed fan delta, braid delta and lacustrine depositional systems in the third-order sequences 7 (SQ7). Eleven seismic facies were chosen in the SQ7 to calculate the area and sediment budget. We also calculated the palaeo-slope parameters in the southern steep slope of the SU, including the gradient of basin margin fault slope belt, the shape, average width, average height, width/height ratio and cross sectional area of palaeo-valley. The gradient of the fault slope break belt was inversely proportional to the area and volume of sediments. The higher gradient corresponded to the smaller area and volume of sediments. The width and cross sectional area of palaeo-valleys dominated the volume and facies of sediments. A larger cross sectional area of a palaeo-valley involved much more sediments supply and more favorable conditions for the origin of large-scale deltas. Because of favorable sediment transportation path and existence of large-scale braid delta, the eastern part of the SU formed better quality reservoir than that in the west.

Glauconite occurs either as unaltered greenish or as altered brownish variety in Upper Cretaceous-Palaeocene sediments in the southeastern corner of Western Siberia. Studied section within the Bakchar iron-ore deposit includes Ipatovo, Slavgorod, Gan'kino and Lyulinvor formations, which are represented by sandstones, siltstones, claystones and oolitic ironstones of coastal-marine fades. The origin of unaltered glauconite is explained by the "verdissement theory". Transgressions during Lower Coniacian, Santonian and Campanian favored the formation of unaltered glauconites in dysoxic to anoxic conditions. Subaerial exposure of glauconite resulted in leaching of potassium, oxidation of iron and formation of iron hydroxides in Upper Coniacian, Maastrichtian and Palaeocene. Glauconite ultimately converts to leptochlorite and hydrogoethite by this alteration. Abundant microscopic gold inclusions, besides sulphides, sulphates, oxides and silicates characterize this glauconite. Mineral inclusions include precious, rare metals and non-ferrous metals. The concentration of gold in glauconite may be as high as 42.9 ppb. Abundant inclusions of various compositions in glauconites indicate enrichment of marine sediments in precious and non-precious metals. While major element composition of glauconites is affected by subaerial exposure, the broadly similar micro-inclusions in both altered and unaltered varieties are possibly related to the comparatively immobile nature of REE and trace elements.(C) 2017 Elsevier B.V. All rights reserved.

A comprehensive study was carried out in order to determine the radioelement and rare earth element (REE) concentrations in beach placer deposits at selected locations along the eastern coast of Andhra Pradesh in India. This was done to evaluate the economic value of these deposits. The findings of this study suggest that high Th and low K concentrations delineate the prospective regions having REE deposits. The beach placers, in general, can be characterized by high thorium and moderate uranium concentrations. The concentrations of REEs vary in the following order: Ce > La> Nd > Pr > Sm > Gd > Dy. Rapid in situ thorium prospectivity coupled with laboratory-based techniques like ICP-MS, as proposed in this study, would help in the identification of prospective REE sources along the coastal placers. The development of indigenous resources of light rare earth elements (LREEs), medium rare earth elements (MREEs), and heavy rare earth elements (HREEs) would decrease the dependence on imports, which have a strategic hold on the production and supply of the REEs, globally.

The neutral particle temperature in the edge region of the Aditya-U tokamak has been measured by recording the hydrogen Balmer alpha emission spectra at 656.28 nm from different lines of sight in both the high and low field sides. The spatial profile of the H α emission has been recorded using a 1 m multi-track spectrometer. The neutral temperature is estimated from the Doppler broadening of the measured H α spectrum by appropriately removing the contribution from the Zeeman splitting of the spectral lines. A computer simulation code was developed to estimate the neutral temperature by including the broadening mechanisms such as Doppler broadening and the Zeeman effect to simulate the H α emission spectrum along with the proper convolution of the instrumental width of the diagnostic system. It has been observed that the high field side neutral temperature (~4–6 eV) during plasma flat top is almost twice that of the low field side (~2–3 eV) suggesting poloidal asymmetry in the neutral temperature.

The first Indian tokamak ADITYA, operated over 2 decades with circular poloidal limiter has been upgraded to a tokamak named ADITYA Upgrade (ADITYA-U) for attaining shaped-plasma operations with open divertor in single and double-null configurations. The experimental research in ADITYA-U has made significant progress, since last FEC 2016. After installation of PFC and standard tokamak diagnostics in ADITYA-U, the Phase-I plasma operations has been initiated from December 2016 with graphite toroidal belt limiter. Ohmically heated circular plasmas supported by filament pre-ionization with plasma parameters, Ip ~ 80 – 95 kA, duration ~ 80 – 180 ms with maximum toroidal field ~ 1T and chord-averaged electron density ~ 2.5 x 10^19 m^-3 has been successfully obtained. The runaway electron (RE) generation, transport and mitigation experiments along with MHD activities and density enhancement with H2 gas puffing experiments have carried out in Phase-I, which is completed in March 2017. The Phase-II operation preparation in ADITYA-U includes calibration of magnetic diagnostics followed by commissioning of major diagnostics and installation of baking system. After repeated cycles of baking the vacuum vessel up to ~ 135°C, the Phase-II operations resumed from February 2018 and are continuing to achieve plasma parameters close to the design parameters of circular limiter plasmas using real time plasma position control. The plasma current has been raised to ~ 135 kA in phase-II with maximum chord averaged electron density of ~ 4 x 10^19 x m^-3. Hydrogen gas breakdown has been observed in more than ~ 2000 discharges including Phase-I and Phase-II operation without a single failure. Several experiments, including the control of REs with fuelling of Supersonic Molecular Beam Injection as well as sonic H2 gas puffing during current flat-top, MHD modes studies using multiple periodic gas puffs and radiative improved modes using Neon gas puff have been carried out. The experimental results from Phase-I and Phase-II operations of ADITYA-U tokamak are discussed in this paper.

The formation of a density blob in the boundary region of a tokamak plasma is widely believed to be due to the presence of poloidal velocity shear that differentially breaks off a radially elongated streamer structure. However, blobs have also been experimentally detected in the absence of poloidal velocity shear. We ascribe the formation of such blobs to the differential stretching of the streamer arising from a radial velocity shear and thereby present a unified picture of the breaking mechanism that takes into account both the processes in a synergistic manner. Our universal condition for blob formation is validated from detailed numerical simulations of the edge turbulence in a typical L-mode scenario.

Tidal sand bars and tidal sand ridges are extensively developed in the macrotidal Gulf of Khambhat, offshore western India. The inner and outer regions of the gulf are characterised by the development distinct tidal sand bodies with discrete geometries and dimensions. The outer gulf ridges are long, narrow, curvilinear and several metres high (similar to 20 m). They are asymmetric in cross-section and migratory in nature, forming 'ribbon' like sand bodies separated by tidal channels. Active dunes on these ridges indicate the presence of sand and their orientation parallel to palaeo-shorelines supports a tidal origin. In contrast to the outer gulf tidal sand ridges, sand bars associated with macrotidal estuaries flanking the Gulf of Khambhat typically have an elongate to diamond shape and are only hundreds of metres in width and a few kilometres length. These tidal sand bars occur in the estuary mouths and within the tidally influenced fluvial reaches of the rivers flowing into the gulf. The height of these sand bars is in the range similar to 1-3 m. Due to high tidal ranges and bi-directional flow the sand bars do not develop significant height and are formed between the mutually evasive ebb and flow channels. Their bi-directional foresets and the presence of abundant mud drapes associated with the dunes within in-channel sand bars indicate a tidal origin. The Gulf of Khambhat acquired the present configuration in the last few thousand years since the Pleistocene sea-level lowstand (last glacial maximum, similar to 18 Ka) when the entire continental shelf was subaerially exposed and rivers down-cut into the coastal plain. With increasing sea-level rise, the exposed shelf was drowned, flooding parts of the Modern western Indian peninsula, and large tidal sand ridges formed in the outer gulf. After the fall of sea-level at 2 ka the gulf acquired the Modern configuration with multiple estuaries on both coastlines, rivers supplied the embayment with sandy sediment, and tidal sand bars formed in the Modern estuaries. Quantitative data gathered from the Modern Gulf of Khambhat indicates that for the P50 case, a vertical drill hole will encounter tidal sand bodies (ridges and bars combined) of approximate dimensions 1700 m long, 470 m wide and 1.5 m high, with a spacing of 400 m. In subsurface hydrocarbon reservoirs, where data is sparse and only limited amount of core is available, this quantitative dataset can be useful to constrain subsurface geocellular models. Also, the overall geometry, distribution and aspect ratio of the tidal sand ridges and tidal sand bars can be used to identify ancient counterparts through seismic geomorphology or in core. (C) 2016 Elsevier Ltd. All rights reserved.

Plasma flows and their profiles in edge and scrape-off layer (SOL) regions of a tokamak plasma are important as these can modify the interchange plasma turbulence. These flows have been investigated in the presence of neutral gas numerically using the two-dimensional model equations. A reduction of poloidal flows, radial particle, and energy fluxes has been observed in the edge and SOL regions by the presence of the neutral gas. The reduction of radial flux is due to the reduction in the radial velocity of the plasma blob. We have investigated Reynolds stress in the presence of the gas. It is found that in the presence of ion-neutral collisions, the magnitude of the stress decreases. The gas also reduces the diamagnetic drift frequency in the edge and SOL regions.

Dust events are recorded in the SST-1 tokamak with fast visible imaging and infrared imaging systems. The events are analyzed from the image sequences with an in-house developed dust tracking routine in MATLAB called FINDUST. Specific operating scenarios for dust observation and their deleterious effects on discharge evolution are identified. A clear correlation of the dust events frequency and strength with the successful start-up and discharge evolution is observed over eight consecutive experimental campaigns in SST-1. It has been seen that the electron cyclotron resonance heating (ECRH) generated pre-ionization slab annular-plasma around the fundamental layer is most likely to generate dust, while the strongest effect of the ECRH fundamental layer on the plasma facing components is seen when the confined plasma column disrupts by some means while the ECRH pulse is still ON.

Major disruptions in Aditya tokamak are initiated by the growth and subsequent locking of m/n = 2/1 and 3/1 tearing modes, which leads to the thermal quench of the plasma. Thick filaments are seen to evolve at the low field side (LFS) of the plasma column following the thermal quench, and during the current quench. The number of filaments and inter filament spacing are observed to be related with the plasma stored energy just prior to the disruption. Rapid enhancement of the outward particle flux is seen during the thermal quench phase and the plasma conductivity reduces considerably. Interchange modes, with low poloidal wavenumber, are inferred to grow due to the reduced plasma conductivity and enhanced effective diffusivity. This may be a plausible explanation for the visualization of the thick filaments at the LFS.

Several experiments, related to controlled thermonuclear fusion research and highly relevant for large size tokamaks, including ITER, have been carried out in ADITYA, an ohmically heated circular limiter tokamak. Repeatable plasma discharges of a maximum plasma current of ~160 kA and discharge duration beyond ~250 ms with a plasma current flattop duration of ~140 ms have been obtained for the first time in ADITYA. The reproducibility of the discharge reproducibility has been improved considerably with lithium wall conditioning, and improved plasma discharges are obtained by precisely controlling the position of the plasma. In these discharges, chord-averaged electron density ~3.0–4.0 × 1019 m−3 using multiple hydrogen gas puffs, with a temperature of the order of ~500–700 eV, have been achieved. Novel experiments related to disruption control are carried out and disruptions, induced by hydrogen gas puffing, are successfully mitigated using the biased electrode and ion cyclotron resonance pulse techniques. Runaway electrons are successfully mitigated by applying a short local vertical field (LVF) pulse. A thorough disruption database has been generated by identifying the different categories of disruption. Detailed analysis of several hundred disrupted discharges showed that the current quench time is inversely proportional to the q edge. Apart from this, for volt–sec recovery during the plasma formation phase, low loop voltage start-up and current ramp-up experiments have been carried out using electron cyclotron resonance heating (ECRH). Successful recovery of volt–sec leads to the achievement of longer plasma discharge durations. In addition, the neon gas puff assisted radiative improved confinement mode has also been achieved in ADITYA. All of the above mentioned experiments will be discussed in this paper.

Supersonic molecular beam injection (SMBI) is one of the most effective fuelling methods for injecting neutral particles at very high velocity into the plasma core. Due to higher speed and lower divergence, the beam penetrates several centimetres into the plasma and hence increases the fuelling efficiency. For SST-1 Tokamak, two types of SMBI systems are proposed. One will be installed in the low field side (LFS) while other will be integrated in the high field side (HFS). This paper describes the design, fabrication and implementation of SMBI system in SST-1 Tokamak.