Transverse Oscillations in a Coronal Loop Triggered by a Jet     

S. Sarkar  V. Pant  A. K. Srivastava  D. Banerjee 《Solar physics》2016,291(11):3269-3288

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New triple oxygen isotope data of bulk and separated fractions from SNC meteorites: Evidence for mantle homogeneity of Mars          下载免费PDF全文

Arshad Ali  Iffat Jabeen  David Gregory  Robert Verish  Neil R. Banerjee 《Meteoritics & planetary science》2016,51(5):981-995

We report precise triple oxygen isotope data of bulk materials and separated fractions of several Shergotty–Nakhla–Chassigny (SNC) meteorites using enhanced laser‐assisted fluorination technique. This study shows that SNCs have remarkably identical Δ¹⁷O and a narrow range in δ¹⁸O values suggesting that these meteorites have assimilated negligibly small surface materials (<5%), which is undetectable in the oxygen isotope compositions reported here. Also, fractionation factors in coexisting silicate mineral pairs (px‐ol and mask‐ol) further demonstrate isotopic equilibrium at magmatic temperatures. We present a mass‐dependent fractionation line for bulk materials with a slope of 0.526 ± 0.016 (1SE) comparable to the slope obtained in an earlier study (0.526 ± 0.013; Franchi et al. 1999). We also present a new Martian fractionation line for SNCs constructed from separated fractions (i.e., pyroxene, olivine, and maskelynite) with a slope of 0.532 ± 0.009 (1SE). The identical fractionation lines run above and parallel to our terrestrial fractionation line with Δ¹⁷O = 0.318 ± 0.016‰ (SD) for bulk materials and 0.316 ± 0.009‰ (SD) for separated fractions. The conformity in slopes and Δ¹⁷O between bulk materials and separated fractions confirm oxygen isotope homogeneity in the Martian mantle though recent studies suggest that the Martian lithosphere may potentially have multiple oxygen isotope reservoirs.  相似文献   

Seismicity, Earthquake Hazard and Rising Economy in Asia     

Paramesh Banerjee 《《地质学报》英文版》2018,92(Z1):266-266

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Copper Ore Identification using Spectral Similarity Measurement from Hyperion Image,Mapping of Porphyry Copper Mineralized Zone     

Krishnendu Banerjee  Manish Kumar Jain 《Journal of the Geological Society of India》2018,91(2):239-247

This work illustrates the effectiveness of hyperspectal image spectroscopy and lab spectroscopy in identification techniques of minerals in alteration zone of ore body. The adopted procedure involves testing of Hyperion image spectra, their processing for noise, spectral matching and spectral similarity measurement with selected library spectra. Average weighted spectral similarity; visual and statistical matching techniques were used to select end-members from image spectra. Minimum noise fraction and pixel purity index technique were used to retrieve end-member spectra from hyperion image. Hyperspectral image like hyperion has the capability to deliver laboratory standard spectroscopic result. This paper illustrates the capability of hyperion image spectra in copper ore identification and mapping of chalcopyrite outcrop. A systematic approach has been made in this paper. This approach describes how image end member spectra and laboratory spectra can be co-related to fetch accurate spectral form of chalcopyrite ores. Thus, statistical and graphical comparison has been carried out between image derived end member spectra and laboratory spectra of chalcopyrite for better accuracy. The visual measurements is satisfactory, R = 0.973 for fine and 0.976 for medium grained chalcopyrite ore. Excellent statistical significance levels (90–97%) are found while comparing these spectra. There are many success stories of sub-pixel and N-dimensional feature space methods to separate the hydrothermal alteration zones from iron oxide mixed ore bodies. Thus, unmixing methods are very useful for mapping of most dominating mineral parts of a pixel from hyperspectral images which have coarse spatial resolution. Finally, mapping of mineralized zone has been achieved through sub-pixel based classifiers like spectral angle mapper (SAM), constrained energy minimization (CEM) and adaptive coherence estimator (ACE) techniques.  相似文献   

Determination of seismic wave attenuation in Delhi,India, towards quantification of regional seismic hazard     

Banerjee  Soham  Kumar  Abhishek 《Natural Hazards》2018,92(2):1039-1064

Natural Hazards - National capital of India, Delhi is under moderate to high seismic hazard due to active regional faults such as the Mahendragarh fault, the Delhi Haridwar fault, the Sohna fault,...  相似文献   

Bridge construction and river channel morphology—A comprehensive study of flow behavior and sediment size alteration of the River Chel,India     

Mery Biswas  Puja Banerjee 《Arabian Journal of Geosciences》2018,11(16):467

Human has always modified its surroundings for better adaptation which include the building of urban landscapes, dams, and engineering constructions like bridges and other infrastructures. It has been unveiled from the study of River Chel that when the rail bridge was constructed before 1913, the natural width of the river was nevertheless maintained but the problem was initiated and after the road bridge construction in 1970s when the river width was minimized,the morphological changes started in a large scale. Such modifications have affected nature as well as human communities both positively and negatively. This paper will try to portray the evolution of channel shifting and changes of sediment size regime that the River Chel is experiencing due to the construction of bridges across the middle part of its course. So, this study is concerned about the changes in channel pathway since last 100 years and field-based hydrological parameters and sediment size analysis reveals some distinct changes in the channel planform with alteration of sediment size regime. Simulation of the hydraulic modeling in HEC-RAS specifies the probable affected area with bridges and without bridges in both upstream and downstream of the river course. Hence, the study unveils the alteration of the river hydrology and sediment size caused due to anthropogenic effects and impact of such flow analysis has been evaluated through the bridge scour calculation by CUS method. The discussion concludes that the Odlabari road bridge construction (after 1970) has modified the normal hydrological behavior of the river with a higher probability of bank erosion in downstream and floods in upstream resulting river bottleneck condition.  相似文献   

Analytic hierarchy process and information value method-based landslide susceptibility mapping and vehicle vulnerability assessment along a highway in Sikkim Himalaya     

Polash Banerjee  Mrinal Kanti Ghose  Ratika Pradhan 《Arabian Journal of Geosciences》2018,11(7):139

In hilly areas, highway projects can be a cause of landslides as well as an element of vulnerability due to landslides. Hence, landslide susceptibility mapping of highway corridors can substantially mitigate loss of life and property. For this, a Landslide Susceptibility Assessment Model (LSAM) was developed for a corridor of 27 km along NH 10 in the East Sikkim. Landslide inducing factors viz. Aspect, Distance from Fault, Distance from Road, Drainage Density, Land use and Land cover, Lithology, Plan Curvature, Rainfall, Slope, Soil Depth, and Soil Texture were considered for the study. Results show that areas in proximity to the highway and areas with steeper slope had a higher landslide susceptibility than otherwise. Spatial explicit sensitivity analysis indicated that LSAM was sensitive to distance from the highway and slope. Vehicle vulnerability assessment of base year and horizon years showed that vulnerability increased through time. LSAM is appropriate for hazard mitigation for areas with poor historical data on landslides.  相似文献   

Petrology and geochemistry of the ultramafic–mafic Mawpyut complex,Meghalaya: a Sylhet trap differentiation centre in northeastern India     

Srinanda Chaudhuri  Jyotisankar Ray  Christian Koeberl  Martin Thni  Riya Dutta  Abhishek Saha  Mousumi Banerjee 《Geological Journal》2014,49(2):111-128

The present article describes, for the first time, petrological and geochemical details of the Mawpyut differentiated complex which is related to the Sylhet trap located at Jaintia Hills district, Meghalaya, northeastern India. The Mawpyut complex occurs as an arcuate body that intrudes into the surrounding Shillong Group rocks. The complex in general contains ‘ultramafic’ and ‘mafic’ rocks, as well as minor syenitic veins that postdate the main units. The lithotypes correspond to cumulate and noncumulate units. The cumulate unit is represented by olivine clinopyroxenite, clinopyroxenite, plagioclase‐bearing ultramafic, olivine gabbronorite, mela‐gabbronorite, melagabbro, orthopyroxene gabbro, and gabbro, all with a pronounced cumulus texture. The noncumulate unit is marked by gabbro, monzonite, monzodiorite, and quartzsyenite. The use of several major and trace element variation diagrams suggests that magmatic differentiation led to the formation of cumulate and noncumulate units. In chondrite‐normalized REE diagrams the cumulate rocks show flat LREE and MREE patterns and a moderate positive Eu anomaly (in plagioclase‐bearing ultramafics) due to plagioclase cumulation. The rocks of the noncumulate unit show a strongly fractionated REE pattern and no Eu anomaly. The noncumulate mafic rocks are geochemically comparable to high‐phosphorous/high‐titanium basalts (HPT) indicative of low pressure fractional crystallization. In a primitive mantle‐normalized multielement diagram some of the cumulate rocks show pronounced negative anomalies for K and P, indicating anorogenic mafic magmatism in a within‐plate setting. The rocks of the noncumulate unit show a slight negative anomaly for Yb and a Nb–Ta trough, indicating a subduction‐related signature that perhaps is inherited from subducted sedimentary rocks incorporated during crustal contamination of the derived magma (left after crystal cumulation) with country rocks. Various trace element ratios for the cumulate mafic rocks indicate parent EMI/EMII/HIMU sources with a very limited crustal signature. The noncumulate mafic rocks (corresponding to the derived evolved magma) indicate EMI/EMII/HIMU sources with a pronounced crustal contamination. The Sr–Nd isotopic compositions of the Mawpyut samples typically plot in the continental flood basalt field, with an affinity to the EMII source. The isotopic compositions of the noncumulate rocks also clearly indicate crustal contamination. We suggest that partial melting (involving garnet in the residue) of the enriched mantle source EMI/EMII/HIMU could have derived the parental melt; this melt, in turn, underwent assimilation and fractional crystallization to produce the variety of cumulate‐noncumulate lithologies of the Mawpyut complex. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Changes in the Level of Proteins,Free Amino Acids and Protease Activities of Clarias batrachus in Response to Sodium meta‐arsenite Intoxication     

Randhir Kumar  Tarun K. Banerjee 《洁净——土壤、空气、水》2013,41(12):1196-1200

Increased hazard of arsenic toxicity at many provinces of India causing extensive contamination of their wetlands. To illustrate the consequences of the arsenic menace on the aquatic fauna, a nutritionally important freshwater catfish Clarias batrachus (Linn.) was subjected to the stress of sublethal concentration (1 mg/L; 5% of 96‐h LC₅₀ value) of sodium meta‐arsenite. The alterations induced by the arsenic salt on certain biomolecules (proteins, free amino acids (FAA), and protease activities) in five tissue components (muscle, liver, brain skin, and gills) of the fish using biochemical techniques were estimated. Significant (p < 0.01) decrease in the concentration of proteins in all the tissues (19.74–44.84% in muscles; 3.17–49.39% in liver; 10.05–36.16% in brain; 12.62–52.01% in skin and 7.34–61.69% in gills), and significant (p < 0.01) increase in FAA (6.84–269.89% in muscles; 125.89–358.03% in liver; 1.07–152.90% in brain; 29.31–401.62% in skin and 38.53–165.07% in gills), and protease activities (43.59–183.33% in muscles; 19.52–131.90% in liver; 8.85–46.72% in brain; 33.33–261.53% in skin and 25.39–50.79% in gills) of the exposed fish were observed. This increase in amino acids and enzyme activity point out toward breakdown of protein leading to their depletion.  相似文献   

Variation in U-238 and Th-232 enrichment in U-mineralized zone and geological controls on their spatial distribution,Singhbhum Shear Zone of India     

K. S. Banerjee  R. Guin  J. L. Gutierrez-Villanueva  M. E. Charro  D. Sengupta 《Environmental Earth Sciences》2012,65(7):2103-2110

The determination of the natural radioactivity has been carried out, by means of gamma-ray spectrometry, in exposed rock samples collected from various geological formations across the Singhbhum Shear Zone of India. The spatial variation in the concentration of primordial radionuclides reflects, in general, the geochemical variance among the analyzed rocks and affirms the earlier views on genesis of uranium mineralization. This study further speculates new possibilities of thorium depletion during shearing and metamorphism. All the obtained U-values were more than the worldwide average U-concentration (which is about 40 Bq/kg). Interestingly, U-concentration in mica schists from Singhbhum group of rocks and in slates and argillaceous quartzites from Iron Ore group of rocks was five to seven times higher than the global values. In contrast, the granites in study area showed comparatively lower U-concentration. The overall results suggest the control of complex metamorphism and shearing on U-distribution in the terrane. The contribution of ²³⁸U, ²³²Th and ⁴⁰K to the total radiation dose in the study area was found to be significant ranging from 110 to 310 nGy/h in comparison with the lower global, as well as Indian average values.  相似文献