On the widespread occurence of oxidized chlorites in the pennine zone of the western Italian Alps     

Dr. Niranjan Deb Chatterjee 《Contributions to Mineralogy and Petrology》1966,12(4):325-339

Oxidized chlorites, having optical properties quite similar to those of biotite, stilpnomelane or iron-rich vermiculite, are described from the schistes lustrés and other similar metamorphites of the Pennine Zone of the western Italian Alps. Optical, x-ray, chemical, DTA and infrared spectroscopic data are furnished. From the results of the chemical study it seems reasonable to conclude that the chlorite has undergone an internal oxidation. Possible petrogenetic implications of its occurenee are discussed in some details.  相似文献   

Anomalous soil radon fluctuations – signal of earthquakes in Nepal and eastern India regions     

Argha Deb  Mahasin Gazi  Chiranjib Barman 《Journal of Earth System Science》2016,125(8):1657-1665

The present paper deals with pre-seismic soil radon-222 recorded at two different locations 200 m apart, at Jadavpur University main campus, Kolkata, India. Solid state nuclear track detector method is used for detection of the radioactive radon gas. Two simultaneous 4-month long time series data have been analysed. Anomalous fluctuations in the radon datasets have been observed prior to recent earthquakes in Nepal and eastern India during the monitoring period, mainly, the massive 25th April 7.8 M Nepal earthquake. The simultaneous measurements assist in identifying seismogenic radon precursor efficiently.  相似文献   

Mineralogical evolution of indium in high grade tin-polymetallic hydrothermal veins — A comparative study from Tosham, Haryana state, India and Goka, Naegi district, Japan   总被引：3，自引：0，他引：3  

S. Murao  M. Deb  M. Furuno 《Ore Geology Reviews》2008,33(3-4):490-504

Two tin-polymetallic vein-type deposits widely separated in time and space but with strong similarities in terms of mineralization style, ore mineralogy and chemistry have been studied comparatively with the aim of understanding the mineralogical evolution of In-rich hydrothermal systems. The Tosham deposit, Bhiwani district, Haryana, India, is of Neoproterozoic age and constitutes a Sn–Cu prospect with unusually high In content. The disseminated, crude stockwork and vein mineralization is hosted by greisenised metasedimentary rocks intruded by a porphyritic granite stock and by later rhyolitic effusives. The Goka deposit, Naegi district, Japan is probably of uppermost Cretaceous age and occurs close to a well fractionated ilmenite series granitoid body. The tin-polymetallic vein in the Goka deposit is hosted by a welded tuff unit close to a subvolcanic granodiorite porphyry.The main host minerals of indium in the Tosham and Goka ores are sphalerite, stannite, unidentified Zn–Cu–Fe–In–Sn–S phases and chalcopyrite. Up to 0.48 wt.% In has been noted in the Goka chalcopyrite, whereas at Tosham, the mineral has a maximum In concentration of 1220 ppm. At Goka the sphalerite contains up to 1.89 wt.% In, whereas In-bearing stannite carries up to ca. 9 wt.% of the metal. Roquesite is the other indium mineral present in the Tosham ores, but is absent in Goka. The mineral chemistry of the Tosham and Goka ores suggest that the In-bearing minerals belong to a multi-component Zn–Cu–Fe–(Ag)–Sn–In–S system. Based on various triangular plots of the atomic proportions of the main metals, it is inferred that there are end-member phases, roquesite and stannite, in the Tosham ores co-existing with chalcopyrite. The sphalerite is both pure end-member and Cu–In-bearing in both the Tosham and Goka ores. Some of the analysed stannite grains in Tosham ores could possibly be petrukite. The Zn–Cu–Fe–Sn–In–S system in the two ores has a Sn-poor, high-In solid solution phase and also a Sn-rich, low-In solid solution phase. It seems possible that these two solid solutions were the first to form during hydrothermal ore deposition at high temperatures from a disordered solid solution located at the (Cu + Ag):(Zn + Fe):(In + Sn) = 3:5:2 intersection in the (Cu + Ag)–(Zn + Fe)–(In + Sn) field. With decreasing temperatures, the Sn-poor, In-rich solid solution exsolved the Zn–In-mineral of Ohta [Ohta, E., 1980. Mineralization of Izumo and Sorachi veins of the Toyoha mine, Hokkaido, Japan. Bulletin, Geological Survey of Japan 31, 585–597. (in Japanese with English abstract).] and sphalerite, while the Sn-rich, In-poor solid solution was broken down to stannite and relatively-Cu-rich sphalerite.  相似文献   

Cost Optimization of Reinforced Earth Walls   总被引：1，自引：0，他引：1  

P. K. Basudhar  Amol Vashistha  Kousik Deb  Arindam Dey 《Geotechnical and Geological Engineering》2008,26(1):1-12

This paper deals with optimum cost (objective function) design of geosynthetic reinforced earth retaining walls subjected to static and dynamic loading. The design restrictions are imposed as design constraints in the analysis. Choice of the initial designed length and strength of the reinforcement, which are the elements of the design vectors are made in a way that it forms an initial feasible design vector. Thus the problem is one of mathematical programming. The constraints and the objective function being nonlinear in nature, the Sequential Unconstrained Minimization Technique (SUMT) has been used in conjunction with conjugate direction and quadratic fit methods for multidimensional and unidirectional minimization to arrive at the optimal (minimum) cost of the reinforced earth wall. Optimal cost tables are presented for different combinations of the loading and the developed procedure is validated by taking up an example problem. It has been found from the typical example problem that saving of the order of 7–8% can be made over the conventional design of mechanically stabilized earth (MSE) walls with the aid of design charts.  相似文献   

Carbonaceous and inorganic species in PM<Subscript>10</Subscript> during wintertime over Giridih,Jharkhand (India)     

S. K. Sharma  T. K. Mandal  A. K. De  N. C. Deb  Srishti Jain  Mohit Saxena  S. Pal  A. K. Choudhuri  Saraswati 《Journal of Atmospheric Chemistry》2018,75(2):219-233

Ambient concentrations of organic carbon (OC), elemental carbon (EC) and water soluble inorganic ionic components (WSIC) of PM₁₀ were studied at Giridih, Jharkhand, a sub-urban site near the Indo Gangatic Plain (IGP) of India during two consecutive winter seasons (November 2011–February 2012 and November 2012–February 2013). The abundance of carbonaceous and water soluble inorganic species of PM₁₀ was recorded at the study site of Giridih. During winter 2011–12, the average concentrations of PM₁₀, OC, EC and WSIC were 180.2?±?46.4; 37.2?±?6.2; 15.2?±?5.4 and 18.0?±?5.1 μg m^?3, respectively. Similar concentrations of PM₁₀, OC, EC and WSIC were also recorded during winter 2012–13. In the present case, a positive linear trend is observed between OC and EC at sampling site of Giridih indicates the coal burning, as well as dispersed coal powder and vehicular emissions may be the source of carbonaceous aerosols. The principal components analysis (PCA) also identifies the contribution of coal burning? +?soil dust, vehicular emissions?+?biomass burning and seconday aerosol to PM₁₀ mass concentration at the study site. Backward trajectoy and potential source contributing function (PSCF) analysis indicated that the aerosols being transported to Giridih from upwind IGP (Punjab, Haryana, Uttar Pradesh and Bihar) and surrounding region.  相似文献   

Solution of the equation of transfer for coherent scattering in an exponential atmosphere by Busbridge's method     

T. K. Deb  S. Karanjai 《Astrophysics and Space Science》1992,192(1):127-132

A solution of the transfer equation for coherent scattering in stellar atmosphere with Planck's function as a nonlinear function of optical depth, viz. $$B{\text{ }}_v (T) = b_0 + b_1 {\text{ }}e^{ - \beta \tau } $$ is obtained by the method developed by Busbridge (1953).  相似文献   

Finite volume–based modeling of flow‐induced shear failure along fracture manifolds          下载免费PDF全文

Rajdeep Deb  Patrick Jenny 《国际地质力学数值与分析法杂志》2017,41(18):1922-1942

In this paper, a numerical model to predict flow‐induced shear failure along pre‐existing fractures is presented. The framework is based on a discrete fracture representation embedded in a continuum describing the damaged matrix. A finite volume method is used to compute both flow and mechanical equilibrium, whereas specifically tailored basis functions are used to account for the physics at discontinuities. The failure criterion is based on a maximum shear strength limit, which changes with varying compressive stress on the fracture manifold. The displacements along fracture manifolds are obtained such that force balance is achieved under conditions, where shear stress of the failing fracture segment is constrained to the maximum shear strength at the segment. Simultaneously, the fluid pressure is computed independently of the shear slip. A relaxation model approach is used to obtain the maximum shear limit on the fracture manifold, which leads to grid convergence.  相似文献   

The essence of multifractal detrended fluctuation technique to explore the dynamics of soil radon precursor for earthquakes     

Chiranjib Barman  Hirok Chaudhuri  Argha Deb  Debasis Ghose  Bikash Sinha 《Natural Hazards》2015,78(2):855-877

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SPH procedures for modeling multiple intersecting discontinuities in geomaterial          下载免费PDF全文

R. Pramanik  D. Deb 《国际地质力学数值与分析法杂志》2015,39(4):343-367

A methodology is developed in SPH framework to analyze the behavior of preexisting multiple intersecting discontinuities or joints in rock material. The procedure does not require any additional unknowns to represent discontinuities and to capture velocity jump across them. Instead, a discontinuity is represented by a set of joint particles placed along the discontinuity plane, in which relative velocity and traction vector is evaluated, obeying the Mohr–Coulomb friction law with zero tension constrain. For failure of continuous rock material, the Drucker–Prager yield criterion with tensile cracking is employed in the elastic‐plastic constitutive model. Free‐sip, no‐slip, and symmetric boundary conditions are also implemented in SPH framework for proper representation of physical system. The paper analyzes behavior of a rock sample having a discontinuity plane under uniaxial loading and compares velocity and stress with a theoretical solution derived considering effective vertical stiffness of the joint planes. The efficacy of the proposed method is successfully demonstrated by solving another two problems of jointed rock mass under uniaxial and gravitational loading conditions.Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Origin of Mesoproterozoic Basins of India: Implications on India-Rodinia Assembly     

Sarbani Patranabis Deb 《Gondwana Research》2001,4(4):604-605

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