Spatial Modeling for Base-Metal Mineral Exploration Through Integration of Geological Data Sets     

Venkataraman  G.  Madhavan  B. Babu  Ratha  D. S.  Antony  Joju P.  Goyal  R. S.  Banglani  S.  Roy  S. Sinha 《Natural Resources Research》2000,9(1):27-42

This study involves the integration of information interpreted from data sets such as LandsatTM, Airborne magnetic, geochemical, geological, and ground-based data of Rajpura—Dariba,Rajasthan, India through GIS with the help of (1) Bayesian statistics based on the weights ofevidence method and (2) a fuzzy logic algorithm to derive spatial models to target potentialbase-metal mineralized areas for future exploration. Of the 24 layers considered, five layers(graphite mica schist (GMS), calc-silicate marble (CALC), NE-SW lineament 0–2000 mcorridor (L4-NESW), Cu 200–250 ppm, and Pb 200–250 ppm) have been identified from theBayesian approach on the basis of contrast. Thus, unique conditions were formed based onthe presence and absence of these five map patterns, which are converted to estimate posteriorprobabilities. The final map, based on the same data used to determine the relationships, showsfour classes of potential zones of sulfide mineralization on the basis of posterior probability.In the fuzzy set approach, membership functions of the layers such as CALC, GMS, NE-SWlineament corridor maps, Pb, and Cu geochemical maps have been integrated to obtain thefinal potential map showing four classes of favorability index.  相似文献   

Linear oscillation of the system of two inter-connected satellites about the position of equilibrium for small eccentricity near the main resonance     

Sachindra Kumar Sinha  R. B. Singh 《Astrophysics and Space Science》1990,174(2):235-239

In this paper the effect of periodic sine-force on the oscillation of the system has been analyzed in its most general form which covers the resonance as well as non-resonance cases.  相似文献   

Propagation of spherical MHD shock-waves in self-gravitating gas     

S. N. Ojha  Onkar Nath  A. D. P. Sinha 《Astrophysics and Space Science》1990,168(1):13-21

A theoretical model of shock-wave propagation has been studied in a heat-conducting and a self-gravitating medium. The effects of magnetic field has been taken into consideration. The shock is strong enough to neglect the ambient gas pressure. The variation of flow variables behind the shock have been investigated numerically.  相似文献   

Anomalous seismic crustal structure of oceanic fracture zones   总被引：2，自引：0，他引：2  

Robert S. White  Robert S. Detrick  Martin C. Sinha  Marie H. Cormier 《Geophysical Journal International》1984,79(3):779-798

Summary. The seismic structure of crust found within fracture zones falls outside the range of velocity structures observed for normal oceanic crust in the North Atlantic. The crust in fracture zones is frequently very thin and is characterized by low crustal velocities and by the conspicuous absence of a refractor with a velocity typical of oceanic layer 3. Anomalous crust is present in both large- and small-offset fracture zones. Since they are among the most common tectonic features in the ocean basins, and are particularly closely spaced on slow-spreading ridges, fracture zones represent a major source of seismic crustal heterogeneity. We interpret the anomalous crust as a thin, intensely fractured, faulted and hydrothermally altered basaltic and gabbroic section overlying ultramafics that, in places, are extensively serpentinized. The unusually thin crust found within fracture zones and the gradual crustal thinning over a distance of several tens of kilometres on either side of the fracture zones can be explained by two main processes; firstly the cold lithosphere edge opposite the spreading centre at the ridgetransform intersection modifies the normal intrusive and extrusive processes of the spreading centre leading to the accretion of an anomalous and thin igneous section; and secondly each spreading ridge segment is fed from a separate subcrustal magma supply point, so as the magma flows laterally down the spreading centre it generates a crustal section of decreasing thickness, culminating in the very thin crust of the fracture zones at either end of the ridge segment.  相似文献   

Mesozoic neo-tethyan pre-orogenic deep marine sediments along the Indus–Yarlung Suture,Himalaya     

Anshu K. Sinha  Rajeev Upadhyay 《地学学报》1993,5(3):271-281

Shelf, forereef and basin margin (slope) olistoliths (Exotic blocks of limestone) of Permian–Jurassic age are tectonically juxtaposed within the Triassic to Eocene age pre-orogenic, deep abyssal plain turbidites of the Lamayuru. The pre-collision tectonic setting and depositional environment of the limestone olistoliths can be reconstructed from within the neighbouring Zanskar range. The disorganized Ophiolitic Melange Zone, an association of different tectonic rock slivers of Jurassic–Eocene age, is tectonically underlain by the overthrusted Lamayuru Formation and tectonically overlain by the Nindam Formation. Tectonic slivers of Late Jurassic–Early Cretaceous age red radiolarian cherts represent a characteristic lithotectonic unit of the Ophiolitic Melange Zone, those occurring near the contact zone with the Lamayuru Formation, were deposited within the neo-Tethyan deep-ocean floor of the Indian passive margin below the carbonate compensation depth. These tectonic slivers accumulated along the northern margin of the Indus–Yarlung Suture Zone of the Ladakh Indian Himalaya during subduction accretion associated with the initial convergence of the Indian plate beneath the Eurasian plate.  相似文献   

Radio observations of the BL Lae object 1400+ 162     

D. J. Saikia  G. Swarup  R. P. Sinha 《Journal of Astrophysics and Astronomy》1984,5(4):475-482

We present total-intensity and linear-polarization observations made with the VLA at 5 GHz of 1400+ 162, a BL Lac object in a group of galaxies. It has a misaligned triple structure with a prominent radio jet towards the east. There is evidence of a weak counter-jet towards the western component, which also has the more prominent warm-spot. We discuss possible explanations for some of the observed features of this source. Although interaction with the cluster medium is possibly partly responsible for the observed distortion, we suggest that the large observed misalignment could also be due to amplification of a smaller misalignment by projection effects. In the relativistic beaming model, where BL Lac objects arise when the relativistic jets are seen end-on, we suggest that 1400+ 162 is more oblique to the line of sight than most members of this class.  相似文献   

A seismic refraction experiment in the Tyrrhenian Sea     

J. Duschenes  M. C. Sinha  K. E. Louden 《Geophysical Journal International》1986,85(1):139-160

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Extragalactic sources with asymmetric radio structure     

D. J. Saikia  P. Shastri  R. P. Sinha  V. K. Kapahi  G. Swarup 《Journal of Astrophysics and Astronomy》1984,5(4):429-473

We present total-intensity and linear-polarization observations with the Very Large Array (VLA) at λ6 and 2 cm of 17 sources, almost all of which were suspected to have extended emission only on one side of the nucleus. Five of them are still one-sided, three appear unresolved, while seven have radio lobes on both sides of the nucleus. The outer components in the double-lobed sources, however, have significantly different surface brightness or are very asymmetrically located with respect to the nucleus.  相似文献   

Effect of solar radiation pressure on the motion and stability of the system of two inter-connected satellites when their center of mass moves in a circular orbit     

Sachindra Kumar Sinha  R. B. Singh 《Astrophysics and Space Science》1987,129(2):233-245

The effect of the perturbative force, solar pressure, on the motion and stability of two cableconnected satellites in the Earth's central gravitational field of force has been studied. The osculating plane of the orbit of the centre of mass has been supposed to be inclined at a constant angle with the plane of the ecliptic. The particular solutions of the nonlinear, non-homogeneous and non-autonomous equations of relative motion in three-dimensional cases have been obtained.The particular solution in which the system lies wholly along the radius vector joining the attracting centre and the centre of mass of the system under the central attracting force alone was found to be stable (cf. Singh, 1973). It has been established in our case too that the same particular solution remains stable if the parameter of the solar pressure lies within a certain limit.  相似文献   

Spectral reflectance characteristics of soils and its correlation with soil properties and surface conditions   总被引：1，自引：0，他引：1  

A. K. Sinha 《Journal of the Indian Society of Remote Sensing》1986,14(1):1-9

In-situ spectral reflectance of soils was measured at various test sites of India in four spectral bands within the visible and near-infrared wavelength comparable to Landsat Multispectral Scanner (MSS). Reflectance behaviour of soils under different field conditions was analysed and the spectral reflectance curves for different soil types were obtained. Soil samples pertaining to each test site were analysed for mechanical composition, physioco-chemical properties to identify their relationship with soil reflectance. These spectral reflectance curves were further examined as to their usefulness in discriminating various soil types. Five distinct soil types namely, Black cotton soils (Typic Pellusterts), Marine Soils (Typic Halaquepts), Lateritic Soils (Plinthic Tropohumults), Alluvial Soils (Typic Ustochrepts), Coastal Sandy Soils (Typic Psammaquents), were discriminated on the basis of significant relationships between the spectral reflectance data and soil properties.  相似文献