PGE geochemistry of low-Ti high-Mg siliceous mafic rocks within the Archaean Central Indian Bastar Craton: implications for magma fractionation

Boninite-norite (BN) suites emplaced in an intracratonic setting in Archaean Cratons, are reported from many parts of the world. Such high-Mg low-Ti siliceous rocks are emplaced during Neoarchaean-Paleoproterozoic. The Archaean central Indian Bastar Craton also contains such a boninite-norite suite, which occurs in the form of dykes and volcanics. The spatial and temporal correlation of these high-Mg low-Ti siliceous rocks with similar rocks occurring around the northern Bastar and Dharwar Cratons probably represent a Bastar-Dharwar Large Igneous Province during the Neoarchaean-Paleoproterozoic. Platinum group element (PGE) abundances in these rocks provide constraints on their geochemical evolution during the Neoarchaean-Paleoproterozoic. The PGE geochemistry of the boninite-norite suite from the southern part of the central Indian Bastar Craton is presented to understand their behaviour during magma fractionation. In primitive mantle-normalized plots all samples have similar PGE fractionated patterns that are enriched in Pd, Pt and Rh relative to Ru. The Pd/Ru ratios for eight samples range from 2.0 to 7.0 which is higher than primitive mantle (primitive mantle Pd/Ru ≈1.2). The Pd/Pt ratios range between 0.2–2.5 with an average value of 0.7 which is near chondritic (primitive mantle Pd/Pt ≈0.5). PGE variations in these rocks together with those of major and other trace elements are consistent with a model involving olivine fractionation along with chromite as a cotectic phase. The Pt fractionation from Pd and Rh is controlled by both olivine and chromite crystallization at an early stage during high temperature crystal fractionation when the Pt was strongly compatible and Pd and Rh were incompatible. Strong negative correlations of the S content with iron and TiO₂ plus lithophile element contents of the rock suggest a decrease of the S solubility in the parental high-Mg magma and separation of an immiscible sulfide liquid with decreasing temperature. Palladium plus other available chalcophile elements (e.g., Re, Au, Ag) have been fractionated in this immiscible sulfide liquid after considerable olivine fractionation of the magma.     

Role of selected riparian herbs in reducing soil erosion and nutrient loss under simulated rainfall

The native riparian herbs such as Leonotis nepetaefolia (L.) R. Br., Cassia tora L., Ageratum conyzoides L., Parthenium hysterophorus L. and Sida acuta burm f., dominant on the bank of River Damodar in Eastern Jharia Area, Dhanbad (India), were selected to assess experimentally their quantitative role in conserving the soil and reducing water runoff and nutrient (N and P) losses. A total of 42.5 mm simulated rainfall were applied at 30 cm h⁻¹ rain intensity on both vegetated and bare plots. The collected runoff water and eroded soil from each plot were determined in terms of soil, water and nutrient conservation value (CV). Among the vegetated plots, soil CV ranged from 30 to 85% and water CV from 20 to 48%. Nutrient (N and P) CV varied from 22 to 65% for total-N, 48 to 80% for ammonia-N and 50 to 86% for nitrate-N. CV for total-P varied from 40 to 62%, inorganic-P from 42 to 60% and organic-P from 20 to 58%. In a stepwise multiple regression equation comprising four independent variables (canopy cover, litter mass, soil moisture and plant biomass), canopy cover explained 70–88% (P < 0.01) of variability in conserving soil, water and nutrient. The losses through runoff water and eroded soil from vegetated plots were found to be minimized to a great extent as compared to bare plots. The role of these species in maintaining the texture and fertility status of riparian soil is discussed.     

Effects of coronal mass ejections on distant coronal streamers

The effects of a large coronal mass ejection (CME) on a solar coronal streamer located roughly 90° from the main direction of the CME propagation observed on January 2, 2012 by the SOHO/LASCO coronograph are analyzed. Radial coronal streamers undergo some bending when CMEs pass through the corona, even at large angular distances from the streamers. The phenomenon resembles a bending wave traveling along the streamer. Some researchers interpret these phenomena as the effects of traveling shocks generated by rapid CMEs, while others suggest they are waves excited inside the streamers by external impacts. The analysis presented here did not find convincing arguments in favor of either of these interpretations. It is concluded that the streamer behavior results from the effect of the magnetic field of a moving magnetic flux rope associated with the coronal ejection. The motion of the large-scale magnetic flux rope away from the Sun changes the surrounding magnetic field lines in the corona, and these changes resemble the half-period of a wave running along the streamer.     

Effect of metal content on chlorophyll fluorescence and chlorophyll degradation in lichen Pyxine cocoes (Sw.) Nyl.: a case study from Uttar Pradesh,India

The major aim of the present study is to identify the relationship of physiological parameters of the photosynthetic system with the elemental content of the naturally growing lichen Pyxine cocoes. The epiphytic foliose lichen P. cocoes was used as biomonitoring indicator and effect of atmospheric pollutants on physiological integrity was examined. Potential quantum yield of Photosystem II (fluorescence ratio Fv/Fm), chlorophyll degradation ratio and quantitative estimation of Al, As, Cd, Cr, Cu, Pb, Fe and Zn contained in the lichen thallus were ascertained. Statistical analysis revealed significantly positive correlations between Fv/Fm and element contents (Al and Cr). The chlorophyll degradation as well as alteration in the pigment content was found to be the most sensitive parameters to assess the vitality of lichen thallus against polluted environment. The species accumulated higher amounts of elements (Al, As, Cu, Fe and Zn) in the polluted sites as compared to the non polluted sites. It was also evident from this study that vehicular emission played a significant role in the release of elements as pollutants in the surrounding environment. The effectiveness of this lichen could be further investigated by comparing this species with other biomonitors.     

Appraisal of land use/land cover of mangrove forest ecosystem using support vector machine

Human activities in many parts of the world have greatly changed the natural land cover. This study has been conducted on Pichavaram forest, south east coast of India, famous for its unique mangrove bio-diversity. The main objectives of this study were focused on monitoring land cover changes particularly for the mangrove forest in the Pichavaram area using multi-temporal Landsat images captured in the 1991, 2000, and 2009. The land use/land cover (LULC) estimation was done by a unique hybrid classification approach consisting of unsupervised and support vector machine (SVM)-based supervised classification. Once the vegetation and non-vegetation classes were separated, training site-based classification technology i.e., SVM-based supervised classification technique was used. The agricultural area, forest/plantation, degraded mangrove and mangrove forest layers were separated from the vegetation layer. Mud flat, sand/beach, swamp, sea water/sea, aquaculture pond, and fallow land were separated from non-vegetation layer. Water logged areas were delineated from the area initially considered under swamp and sea water-drowned areas. In this study, the object-based post-classification comparison method was employed for detecting changes. In order to evaluate the performance, an accuracy assessment was carried out using the randomly stratified sampling method, assuring distribution in a rational pattern so that a specific number of observations were assigned to each category on the classified image. The Kappa accuracy of SVM classified image was highest (94.53 %) for the 2000 image and about 94.14 and 89.45 % for the 2009 and 1991 images, respectively. The results indicated that the increased anthropogenic activities in Pichavaram have caused an irreversible loss of forest vegetation. These findings can be used both as a strategic planning tool to address the broad-scale mangrove ecosystem conservation projects and also as a tactical guide to help managers in designing effective restoration measures.     

Indications of an extreme event deposits along the west coast of India: evidences from GPR investigations

The ground-penetrating radar (GPR) was used to trace the subsurface details in the Palshet coastal zone (Maharashtra) as it exhibits an interesting array of geomorphological features. Furthermore, our main goal was to identify and locate features that might have formed during a reported extreme event and its effects on the flow of the nearby Sundri River. Two profiles (8 and 4 m depth) were collected across the beach and along the backshore, respectively. While the 8-m depth profile (west to east; across the beach) indicates a series of coastline regression in this area, the 4-m depth profile along the coastline (north to south) in the backshore zone reveals two significant incidents viz., (1) stages of development of the paleo-channels that indicate the migration of the Sundri River towards south and (2) huge sediment deposits up to 2.5-m thick in the backshore area. The erosional relict surface (~2.5 m depth) was traced along with various spells of sediments that perhaps occurred due to an extreme event. Sand samples were collected from two trial pits along the GPR profiles to understand the sedimentology and mineralogy in the backshore area. These data together with beach profiles and geomorphological maps suggest that the sands were deposited by an extreme event perhaps during the 1854 cyclonic storm. The sands were trapped in suitable geomorphological sites along the Palshet coast and these sand deposits of about 2.5 m thickness forced the River Sundri to shift its course towards the south. This new revelation facilitates a further study that could focus on the nearby coastal areas to document such extreme event deposits and their influence on the geomorphic set-up.     

Provenance of the late Paleocene sandstones of the Jaisalmer Basin,Western India

Provenance of the late Paleocene sandstone of the Jaisalmer basin has been determined by petrographic and heavy minerals analysis supported by paleocurrent study. Petrography of the quartzose-arenite sandstone reveals an abundance of sub-angular to sub-rounded monocrystalline non-undulatory quartz and some amount of feldspar and rock fragments. The rock fragments are dominated by argillites (slate, phyllite) and limestone. The heavy minerals suite of these sandstones comprises of angular to sub-angular grains of magnetite, zircon, tourmaline, kyanite and staurolite. The paleocurrent analysis indicates bipolar paleocurrent pattern with the dominance of NW flow suggesting that the provenance was in the SE direction of the depositional basin. Q-F-L and Qm-F-Lt diagrams suggest for a provenance at the margin of the craton interior and transitional continental. It is envisaged that the basic igneous rocks of the Deccan basalt, low- to medium-grade metamorphic rocks of the Aravalli belt and Jurassic limestones present in the vicinity are the source rocks for the late Paleocene sandstones of the Jaisalmer basin.     

Environmental impact on coastal wetlands since 4 ka in Cauvery Delta: Palynology and thecamoebian study

Palaeoclimate and Palaeoecological study was carried out in ～2 m sediment core deposited since 4 ka in an estuarine environment along Uppanar River mouth, Cauvery Delta. Palynological and thecamoebian evidences indicate (1) a basal fluvial lacustrine depositional environment (～4–3 ka) characterized by sandy sediment, with low salinity and dominance of non-pollen forms like foraminiferal linings and thecamoebians with a low percentage of pollen and spores and (2) an estuarine environment (since 3 ka) characterized by clayey sediment with high salinity and a good percentage of mangrove and terrestrial pollen along with non-pollen forms. A shift in the depositional environment since ～3 ka indicates monsoonal and geomorphological changes in the coastal wetland. During this period dominance of Avicennia and Cheno/Ams indicate low freshwater runoff from land suggesting a weakened monsoon condition enhanced by anthropogenic activity.     

Use of remote sensing in characterization and management of Dhamni micro-watershed of Chandrapur district of Maharashtra

Soil resource characterization of Dhamni micro-watershed in Chandrapur district of Maharashtra was carried out using IRS-1D LISS-III data in conjunction with field survey and ancillary data. The study indicates that nearly 84.2 per cent of the total geographical area of the watershed is under cultivation. Forest (mainly degraded) occupy only 4.5 per cent area Whereas wasteland with scrub cover 9.4 per cent area of the watershed. Nine soil series were tentatively identified and mapped as soil series association in to five mapping units. These soils belong to order Inceptisol, Vertisol and Mollisol. Except the soils of wasteland with scrub, other soils are moderately suitable for pigeonpea and soybean and have average to good productivity.     

Data analysis of continuous gravitational wave: Fourier transform – II

In this paper we obtain the Fourier Transform of a continuous gravitational wave. We have analysed the data set for (i) a 1-yr observation time and (ii) an arbitrary observation time, for an arbitrary location of detector and source, taking into account the effects arising due to the rotational as well as orbital motion of the Earth. As an application of the transform we considered spin-down and N -component signal analysis.