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The Magba Shear Zone is made up of granites, migmatites, orthogneiss, metagabbro, mafic dyke and mylonites with coarse grained texture, porphyroblastic, granoblastic, cataclastic and mylonitic texture respectively. Structural features and kinematic indicators testify the syntectonic emplacement of Magba granitoids and also provide detailed information on the relative timing of deformation as follows: (1) D1 of tangential movement immediately followed by (2) the D2 phase which is heterogeneous simple shear in dextral transpressive context with a NW-SE direction (3) D3 tectonic phase is marked by sinistral transpressive tectonic and superposed folding with a NE-SW kinematic direction. Combined ductile NE-SW shear movements and NWSE compressional movements defined a transpressional tectonic regime during the D3 deformation (4) A brittle stage D4 is controlled by transcurrent tectonics and responsible for the emplacement of faults, and joints. The Magba granites would have intruded along sub-vertical mid-crustal feeder channels and were emplaced as a sheet or sheets along the shear zone during the early stage of the C3 shearing, followed by gabbro and mafic dyke at the late stage. Strike-slip dilatancy pumping under transpressive tectonic is suggested as a possible mechanism for the emplacement of the Magba granites. Copyright 2017 Geological Society of India

The Tikar plain is located on the Cameroon Central Shear Zone. It is also part of the North Equatorial Pan-African Belt. It is formed of granitoids intruded in places by mafic and intermediate dykes. The mafic dykes are essentially banded gabbros composed of plagioclases, pyroxenes, amphiboles, biotites and opaques. Their textures range from porphyroblastic to porphyritic. The intermediate dykes are monzonites and monzodiorites and are characterized, respectively, by cataclastic and mylonitic textures. The minerals identified are amphiboles, potassium feldspar, pyroxenes, epidotes, sphenes and opaques. Seritization reaction is mostly present on the mafic and intermediate dykes, while chloritization is much more pronounced on the intermediate dykes. The Tikar plain dykes are high-k calc-alkaline to shoshonitic. They are characterized by low to moderate SiO 2 content (42.08–61.96 wt%), low to high TiO 2 (0.47–2 wt%) and low Ni (1.48–99.18 ppm) contents. The mafic dykes show fractional trends with negative anomalies of Zr, U and P and positive Rb, Ba, Ta, Pb and Sr in multi-element diagrams, while the intermediate dykes present negative anomalies of Nb, Ta, Zr, Sr P and Ti and relative positive anomalies of Rb, Ba and Pb. The rare-earth elements (REE) patterns show positive Eu anomalies for the mafic dykes and negative anomalies for the intermediate dykes. The REE spectrum of all the dykes shows enrichment in LREE with relatively flat HREE, which can indicate arc magmatism. In the Zr–Ti/100–Sr/2 diagram, the mafic dykes plot in the island arc tholeiite and calc-alkaline basalt fields. The Th, Nb and LREE concentrations indicate that the subducted lithosphere with crustal component contributed to generation of the intermediate dykes of the Tikar plain. The geochemical characteristics of the mafic to intermediate dykes suggest their derivation from a various degree of partial melting in the garnet spinel facies, probably between depths of 80 and 100 km. The collision between the Central African Fold Belt and the northern edge of the Congo craton resulting in crustal thickening, sub-crustal lithospheric delamination and upwelling of the asthenosphere may have been the principal process in the generation of the intermediate dykes in the Tikar plain. The magma for the mafic and intermediate dyke would have migrated through the faults network of the Central Cameroon Shear Zone before crystallizing in the granito-gneissic basement rocks.

The sediments of 90 rivers from five states along the west coast of India were analysed for their chemistry. The major element ratios of sediments suggest lateritic soils in Kerala, lateritic soils admixed with particulates weathered from Fe–Mn ores in Karnataka and Goa and, non-lateritic, chemically weathered soils in Maharashtra and Gujarat. The sediments from the Archean-Proterozoic (A-P) terrain are strongly weathered, while those from Deccan Traps (DT) terrain are intermediate to strongly weathered. The mean total rare earth elements content (∑REE) of sediments from the rivers of Kerala is much higher than in other states. ∑REE shows strong positive correlation with oxides of Fe, Mn and P from A-P terrain and Al, Fe and Ti from DT terrain and, strong positive correlation with heavy metals (Zr, U, Hf and Th) from both terrains. The low Sm/Nd and Y/Ho ratios corresponding to high chemical index of alteration (CIA) and, high ratios corresponding to high and low CIA are typical. The Post-Archean average Australian shale (PAAS)-normalized REE shows LREE- and MREE-enriched patterns in the sediments of Kerala and MREE- and HREE-enriched patterns in other sediments. Distinct positive Ce anomaly occurs in the sediments of Karnataka, Goa and south Maharashtra and, weak positive to weak negative Ce anomaly in the sediments of other states. The Eu anomaly is negative in the silts of south Kerala and positive in all other sediments. The primary sources for REEs are adsorbed REEs onto secondary mineral phases and clay minerals and, heavy minerals. The change in REE patterns is primarily related to the source rock composition. Fractionation of REEs is related to the intensity of chemical weathering, supply of REE and transport processes. The average REE composition of river sediments from peninsular India is more mafic than in UCC and World Rivers Average Clay.

We present field, petrographic, mineralogical and whole-rock geochemical data for part of the Neoarchean granite and associated microgranular enclaves (MEs) occur in the Nalgonda region, NE part of Eastern Dharwar Craton (EDC), and demonstrate the end-member magma mixing processes in the petrogenesis of the host granite. Extensive occurrence of ME and uni-directional flow band structures (N–S trend) in all the studied outcrops exposed over about 20 km depict that intensive magma mixing–mingling occurred at magma chamber scale. MEs are the portions of intermediate mafic magma that had interacted at two stages with acidic host granite. Mixing at the initial stage promoted efficient thorough mixing which resulted in rapakivi texture and mesocratic enclaves. Wispy filament structures around these enclaves indicate that mafic magma globules were mechanically diluted in the host granite magma by chaotic advection. These filamental magmas were further linearly diluted along with convection-related flow of the host magma. Smaller mafic globules also got linearly stretched along with this flow. Upon solidification of the host magma, these wispy mafic filaments were preserved as flow structures. The second stage of mafic magma mixing did not promote thorough mixing due to the large viscosity contrast with the host granite magma and preserved their physical entity. These enclaves are melanocratic with sharp boundary and devoid of gradational contact and filament structures around it. They characteristically show network of granitic vein injection which often show crenulation folding. These evidences indicate that during the second-stage interaction, the enclave magma was rigid to plastic nature with respect to the host granite magma. Coherent linear Harker variation trend of CaO, MgO, TiO 2 , K 2 O/Na 2 O, V, Y and Sc indicates that mixing has promoted to develop chemical gradient between ME and host granite magmas. Mechanical dilution by chaotic advection must have enhanced the chemical diffusion of both magmas. Smooth decreasing Harker trend of Y content in both the magmas indicates that theyhad undergone certain degree of fractional crystallisation. In contrast, elements like Rb, Ba and Sr with large value of diffusion coefficient ( D ) show scattered behaviour in element–element plots suggesting that diffusive fractionation was active during chaotic advection mixing. It is concluded that heterogeneity in compositional variation of Nalgonda granite can be attributed to difference in degree of mechanical dilution of mafic magma, fractional crystallisation and diffusive fractionation. The geochemical evidences indicate the role of subduction in the evolution of these rocks.

This paper undertakes a thorough review of the legislative and policy framework of water supply and sanitation in India within the larger backdrop of the universal affirmation of right to water and sanitation under the UN WASH initiatives, first articulated under the Millennium Development Goals (MDGs). Recognizing the proactive role played by the Indian judiciary in this regard, the paper examines various patterns of judicial reasoning in realising the right to water and sanitation as Constitutional rights of citizens. The paper observes that through a consistent ‘rights-based’ approach, the Indian judiciary has systematically articulated and achieved the objectives of the UN WASH initiatives long before they were spelled out under the MDGs. The paper highlights the need for the Government to recognise and incorporate judicial insights in implementing developmental projects under the WASH initiatives.

This paper addresses the issue of the Mullaperiyar Dam dispute between Kerala and Tamil Nadu with specific reference to the two judgments delivered by the Supreme Court of India on the matter. This paper attempts to examine the arguments, facts, and the judgment of the Court on each of the primary issues raised during the course of the dispute. The first case was filed by the Mullaperiyar Environmental Protection Forum in 2001, wherein the Court adjudged the case in favour of the respondents, the State of Tamil Nadu. Consequently, due to certain developments, examined in the course of the second case, the State of Tamil Nadu filed a petition before the Supreme Court against Kerala in 2006 seeking relief for the actions on the part of the latter after the judgment in the first case. A Constitution Bench was constituted to adjudicate this case, which re-examined certain issues raised during the first case and conclusively laid down its decision in favour of Tamil Nadu.

The early Archean represents an important eon in the evolution of the earth’s continental crust and could provide insights into the nature of geodynamic processes that operated during that period. The Singhbhum Craton from the Indian Shield is the only major archive of Palaeo–Mesoarchean geological processes. The Palaeoarchean granitoids from the Keonjhar area of Singhbhum Craton are potassic granites and granodiorites of calc-alkaline affinity. Their age and elemental concentrations resemble the low Al₂O₃ granites reported from the Eastern Pilbara Craton of Australia. The geochemical systematics of these granitoids suggests their derivation due to crustal reworking involving partial melting of a tonalitic source, possibly older metamorphic tonalitic gneiss (OMTG). The OMTG could have been derived due to the melting of an enriched basaltic source at the base of an oceanic plateau. In the second stage, the resultant underplating at crustal levels caused the reworking that led to intracrustal melting and differentiation of OMTG to form potassic granites, similar to that of Keonjhar pluton. Consolidating the evidences from the available geochemical and isotopic studies with our own data and correlating them with the geophysical evidences, we interpret that the Keonjhar granitoids are the product of intracrustal melting in an oceanic plateau setting.

We present field, petrographic and mineral compositions of biotite, amphibole, and feldspars from Neoarchean Nizamabad granites from the northeastern part of the Eastern Dharwar Craton, southern India. These granites are classified as hornblende biotite granite (HBG), biotite granite (BTG), monzogranite (MG), and microgranular enclaves (ME) hosted in HBG and BTG. The temperature estimates using amphibole and biotite thermometry exhibit similar results, with higher temperatures for HBG (818 to 859 ±22°C) and ME (800 to 855 ±22°C), and slightly lower temperatures for BTG and MG (829 to 830 ±12°C and 820 to 829 ±12°C). Based on barometry, HBG amphiboles crystallized at pressures between 363 and 448 ±60 MPa (avg. P HBG  = 398 MPa), whereas the MEs crystallized at pressures between 313 and 438 ±60 MPa (avg. P ME  = 386 MPa). The estimated pressures suggest that these granites crystallized at depths of 14–15 km, corresponding to the upper to mid-continental crust. The amphibole compositions reveal that these granites crystallized from a water-rich magma, with >5 wt.% H 2 O and evolved under high oxidizing conditions NNO + 2 (Nickel–Nickel–Oxide), corresponding to magnetite (oxidized) series granites. The amphibole and biotite compositions suggest a crust-mantle mixed source for HBG, ME, and BTG, while the MG is purely crustal derived. The water-rich and highly oxidizing conditions of the parental magmas rule out a lower crustal granulitic source for the Nizamabad granites. The amphibole and biotite compositions suggest their crystallization from calc-alkaline parental magma in a subduction setting at high oxygen fugacity ( f O 2 ) conditions. This study infers the role of convergent margin tectonics in the emplacement of these granites, and their compositional variability is attributed to crust–mantle interactions in this domain of the Eastern Dharwar Craton. Research Highlights The granitoids from the NE part of the Eastern Dharwar Craton are characterized as hornblende biotite granites (HBG), biotite granites (BTG), monzogranite (MG), and mafic enclave (ME). Estimated pressures suggest that these granites crystallized at depths of 14 to 15 km, corresponding to the upper to mid-continental crust. The water-rich (> 5 wt.% H 2 O content) and high oxidizing conditions (NNO+2) of HBG, BTG, and ME corresponds to magnetite (oxidized) series granites. The amphibole and biotite compositions from the Nizamabad granites suggest the crust-mantle mixed source for HBG, ME, and BTG, while the MG are purely crustal derived. The compositions of these granites suggest their crystallization from calc-alkaline parental magma in subduction settings at high oxygen fugacity ( f O 2 ) conditions. The study infers the role of convergent margin tectonics in the emplacement of compositionally variable granitoids in the NE part of the Eastern Dharwar Craton.

The rare earth elements (REE) in the clay fraction of sediments in 15 rivers and their estuaries along the east coast of India were analysed in this study. The total REE content (ΣREE) varied from 130.98 to 289.85 μg/g and from 70.89 to 352.61 μg/g in rivers and estuaries respectively. The ΣREEs of estuarine clays (except the Brahmani and Baitarani) was lower than in rivers. The Post-Archean average Australian Shale-normalized REE patterns in rivers and estuaries were similar and categorized into three types. The REE patterns reflect the composition of dominant geological formations in river basins and extent of sediment mixing from different sources during transport. Hydrodynamic conditions controlled the abundance and fractionation of REE in the estuaries. The Sm/Nd ratios of clays were largely controlled by mineral composition and Y/Ho ratios were affected by sedimentary processes in the estuaries.

Savonius wind turbines have distinct advantages in terms of simplicity, low noise, and ease of manufacturing, yet they are not preferred for large-scale power generation due to their lower aerodynamic performance and high wind loads. This study is aimed at reducing the thrust load with retractable type telescopic blades. This novel telescopic Savonius turbine is tested in an open jet wind tunnel to assess the performance in terms of torque, power, and thrust on the rotor. The dynamic and static characteristics are obtained for both extended and retracted configuration after correcting the experimental data for wind tunnel blockage. A preliminary numerical study is carried out in an effort to determine the variation of the drag coefficient in relation to the bucket thickness. The proposed telescopic turbine demonstrates a reduction in thrust load of 72.4% with a maximum power coefficient of 0.14 at the tip speed ratio of 0.7 compared to an extended operating configuration, similar to a conventional Savonius turbine. Thus, the telescopic Savonius turbine can be scaled up to higher kilowatt capacity with the cost comparable to other high-speed rotors such as Darrieus or horizontal axis wind turbines.