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41.
In high-grade (granulite facies) quartzofeldspathic rocks the progressive development of a fabric records contrasting deformation
behaviour of quartz and feldspar. Feldspar has undergone deformation mainly by recrystallization-accommodated dislocation
creep and produced smaller recrystallized grains progressively in the course of deformation. Quartz has not deformed solely
by dislocation creep but also by a diffusion-controlled mechanism. Dislocation climb is important in the dislocation creep
of quartz. In contrast to feldspar, quartz grains have not recrystallized into smaller grains at any stage of deformation.
Rather, they have transformed initially to short monocrystalline ribbons and ultimately to long polycrystalline ribbons. This
textural change of quartz is a continuous process and has taken place in the course of bulk textural change of the rocks during
the deformation. 相似文献
42.
Basanta Kumar Samanta 《Pure and Applied Geophysics》1966,63(1):68-81
Summary A direct method has been applied in this paper to find the stresses in some steadily rotating, self-gravitating spherical earth models. 相似文献
43.
D S Mackay S Samanta D E Ahl B E Ewers S T Gower & S N Burrows 《Transactions in GIS》2003,7(1):139-153
All land surface process models require parameters that are proxies for spatial processes that are impractical or impossible to measure. Recent developments in model parameter estimation theory suggest that information obtained from calibrating such models is inherently uncertain in nature. As a consequence, identification of optimum parameter values is often highly non–specific. A calibration framework using fuzzy logic is presented to deal with such uncertain information. An application of this technique to calibrate the sub–canopy controls on transpiration in a land surface process model demonstrates that objective estimates of parameter values and expected ranges of predictions can be obtained with suitable choices for objective functions. An iterative refinement in parameter estimates was possible with conditional sampling techniques. The automated approach was able to correctly identify parameter tradeoffs such that two strongly different sets of parameters could 相似文献
44.
Natural Hazards - The present paper assesses the slope stability of the Tungnath Temple at Rudraprayag District, in the Indian state of Uttarakhand, and suggests the remedial measures. The... 相似文献
45.
S. Parida S. K. Barik B. Mohanty P. R. Muduli S. K. Mohanty S. Samanta A. K. Pattanaik 《International Journal of Environmental Science and Technology》2017,14(12):2649-2660
Five trace metals, viz. copper (Cu), chromium (Cr), iron (Fe), mercury (Hg) and zinc (Zn), in three organs (muscle, gills and liver) of four selected fish species (Mugil cephalus, Eleutheronema tetradactylum, Etroplus suratensis and Daysciaena albida) from Chilika lagoon were studied monthly to assess the concentration level and human health risk via consumption. The average and range of metal concentrations (μg g?1) in flesh of the fish species were found to be: Cu (4.15, 3.47–5.03), Cr (0.25, 0.04–0.63), Fe (19.72, 14.51–27.30), Hg (0.07, 0.05–0.08) and Zn (8.09, 4.41–11.36). The metal concentrations measured in the edible muscles of all fish species were found lower as compared to the contents in liver and gill. Analysis of variance revealed a significant difference in trace metal accumulation among the organs (p < 0.001), but the difference among the seasons and fish species was insignificant (p > 0.05), with the exception of Zn accumulation (p < 0.05). The estimated daily intake (EDI) of the trace metals through the consumption of fish as a dietary component varied widely from 0.48 to 21.33% with respect to the corresponding permissible tolerable daily intake (PTDI). The target hazard quotients (THQs) calculated considering these EDIs for individual metals indicated that the Cr and Cu metals dominantly contributed (avg. THQ = 0.198) to represent the hazard index (HI) than other metals (avg. THQ = 0.029). The average HI determined for all the species was <1 (0.484, ranged 0.255–0.605), indicating that these fish species of Chilika are safe for human consumption. 相似文献
46.
J. K. Ghosh J. Bhanja S. Purkayastha T. Samanta S. Sengupta 《Mathematical Geology》2002,34(5):505-528
A geological map is the representation, on a two-dimensional plane, of the disposition of three-dimensional rock bodies exposed on the earth's surface. The problem of mapping is essentially that of dividing an area into homogeneous subregions on the basis of the exposed rock types. Automatic Bayesian methods of model selection using default Bayes factors have been employed to solve the problem of choosing a set of boundaries between homogeneous subregions, assuming no complication excepting low-angle tilting affected rock bodies. The method is tested on two data sets. A sampling scheme for optimum allocation of observation points is also presented. 相似文献
47.
48.
Mainak?ThakurEmail authorView author&#;s OrcID profile Biswajit?Samanta Debashish?Chakravarty 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(8):2381-2404
Multigaussian kriging technique has many applications in mining, soil science, environmental science and other fields. Particularly, in the local reserve estimation of a mineral deposit, multigaussian kriging is employed to derive panel-wise tonnages by predicting conditional probability of block grades. Additionally, integration of a suitable change of support model is also required to estimate the functions of the variables with larger support than that of the samples. However, under the assumption of strict stationarity, the grade distributions and important recovery functions are estimated by multigaussian kriging using samples within a supposedly spatial homogeneous domain. Conventionally, the underlying random function model is required to be stationary in order to carry out the inference on ore grade distribution and relevant statistics. In reality, conventional stationary model often fails to represent complicated geological structure. Traditionally, the simple stationary model neither considers the obvious changes in local means and variances, nor is it able to replicate spatial continuity of the deposit and hence produces unreliable outcomes. This study deals with the theoretical design of a non-stationary multigaussian kriging model allowing change of support and its application in the mineral reserve estimation scenario. Local multivariate distributions are assumed here to be strictly stationary in the neighborhood of the panels. The local cumulative distribution function and related statistics with respect to the panels are estimated using a distance kernel approach. A rigorous investigation through simulation experiments is performed to analyze the relevance of the developed model followed by a case study on a copper deposit. 相似文献
49.
The presence of gas hydrates, one of the new alternative energy resources for the future, along the Indian continental margins
has been inferred mainly from bottom simulating reflectors (BSR) and the gas stability zone thickness mapping. Gas hydrate
reserves in Krishna Godawari Basin have been established with the help of gas-hydrate related proxies inferred from multidisciplinary
investigations. In the present study, an analysis of 3D seismic data of nearly 3,420 km2 area of Mahanadi deep water basin was performed in search of seismic proxies related with the existence of natural gas hydrate
in the region. Analysis depicts the presence of BSR-like features over a large areal extent of nearly 250 km2 in the central western part of the basin, which exhibit all characteristics of a classical BSR associated with gas hydrate
accumulation in a region. The observed BSR is present in a specific area restricted to a structural low at the Neogene level.
The coherency inversion of pre-stack time migration (PSTM) gathers shows definite inversion of interval velocity across the
BSR interface which indicates hydrate bearing sediments overlying the free gas bearing sediments. The amplitude versus offset
analysis of PSTM gathers shows increase of amplitude with offset, a common trend as observed in BSR associated with gas hydrate
accumulation. Results suggest the possibility of gas hydrate accumulation in the central part of the basin specifically in
the area of structural low at the Neogene level. These results would serve as preliminary information for selecting prospective
gas hydrate accumulation areas for further integrated or individual study from geophysical, geological, geochemical and microbiological
perspectives for confirmation of gas hydrate reserves in the area. Further, on the basis of these results it is envisaged
that biogenic gas might have been generated in the region which under suitable temperature and pressure conditions might have
been transformed into the gas hydrates, and therefore, an integrated study comprising geophysical, geological, geochemical
and microbiological data is suggested to establish the gas hydrate reserves in Mahanadi deep water basin. 相似文献