Geophysical anomalies associated with uranium mineralization from Beldih mine, South Purulia Shear Zone, India     

Animesh Mandal  Arkoprovo Biswas  Saurabh Mittal  William K. Mohanty  Shashi Prakash Sharma  Debashish Sengupta  Joydip Sen  A. K. Bhatt 《Journal of the Geological Society of India》2013,82(6):601-606

Beldih mine at the central part of the South Purulia Shear Zone (SPSZ) has been reported with low grade uranium-bearing formation within quartz-magnetite-apatite host in kaolinized formation. Therefore, the present integrated geophysical study with gravity, magnetic, radiometric, very low frequency electromagnetic (VLF) and gradient resistivity profiling methods around the known mineralized zones aimed at identifying the exact geophysical signatures and lateral extent of these uranium mineralization bands. The closely spaced gravity-magnetic contours over the low to high anomaly transition zones of Bouguer, reduced-to-pole magnetic, and trend surface separated residual gravity-magnetic anomaly maps indicate the possibility of high altered zone(s) along NW-SE direction at the central part of the study area. High current density plots of VLF method and the low resistive zones in gradient resistivity study depict the coincidence with low gravity, moderately high magnetic and low resistivity anomalies at the same locations. Moderate high radioactive zones have also been observed over these locations. This also suggests the existence of radioactive mineralization over this region. Along profile P2, drilled borehole data revealed the presence of uranium mineralization at a depth of ～100 m. The vertical projection of this mineralization band also identified as low gravity, low resistivity and high magnetic anomaly zone. Thus, the application of integrated geophysical techniques supported by geological information successfully recognized the nature of geophysical signatures associated with the uranium mineralization of this region. This enhances the scope of further integrated geophysical investigations in the unexplored regions of SPSZ.  相似文献   

Gravitational Field of Domain Walls in Higher Dimension     

Subenoy Chakraborty  Farook Rahaman  Lalit Biswas 《Astrophysics and Space Science》2000,274(4):851-858

In this paper, we study the gravitational field of domain wall in fivedimensional space-time. Exact solutions of Einstein's equations for a scalarfield with a potential V(Ø) are presented, describing thegravitational field of plane symmetric domain walls. The solution showsthat the energy density as well as pressure in the perpendicular directionon both sides of the walls to be reflection symmetric with respect to thewalls.PACS numbers: 98.80 cq, 0450  相似文献   

Solution of non-coherent spectral line transfer problem for finite atmosphere by theF n -method     

R. C. Raymandal  G. Biswas  S. Karanjai 《Astrophysics and Space Science》1988,146(2):311-319

By use of the orthogonality and normalization integrals developed by McCormick and Siewert (1970) a set of singular integral equations suitable forF _n -method is derived for non-coherent spectral line formation problem in finite media.F _n -equations for exit distributions are used to develop some algebraic equations with suitable recursion relations.  相似文献   

Hydrological and geochemical constraints on the mechanism of formation of arsenic contaminated groundwater in Sonargaon,Bangladesh     

Takaaki Itai  Harue Masuda  Ashraf A. Seddique  Muneki Mitamura  Teruyuki Maruoka  Xiaodong Li  Minoru Kusakabe  Biswas K. Dipak  Abida Farooqi  Toshiro Yamanaka  Shinji Nakaya  Jun-ichi Matsuda  Kazi Matin Ahmed 《Applied Geochemistry》2008

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Application of AHP with GIS in drought risk assessment for Puruliya district,India   总被引：1，自引：0，他引：1  

Moumita Palchaudhuri  Sujata Biswas 《Natural Hazards》2016,84(3):1905-1920

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Analysis of eve-teasing potential zones using geospatial technologies and AHP: a study in Midnapore town,West Bengal,India     

Biswas  Priyanka  Das  Kousik  Das Chatterjee  Nilanjana 《GeoJournal》2021,86(3):1043-1072

GeoJournal - Application of geospatial technologies in criminological study is most relevant in present day context. Crime mapping with the help of Geographical Information System is being a very...  相似文献   

Particle creation and non-equilibrium thermodynamical prescription of dark fluids for universe bounded by an event horizon     

Subhajit Saha  Atreyee Biswas  Subenoy Chakraborty 《Astrophysics and Space Science》2015,356(1):141-147

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Comparative Analysis of Phytoplankton Composition and Abundance over a Two-Decade Period at the Land–Ocean Boundary of a Tropical Mangrove Ecosystem     

Haimanti Biswas  Mitali Dey  Dipnarayan Ganguly  Tarun K. De  Sandip Ghosh  Tapan K. Jana 《Estuaries and Coasts》2010,33(2):384-394

Inter-annual variations of phytoplankton abundance and community organization were observed over a two-decade period along with the ancillary parameters at the land–ocean boundary associated with the Sundarban mangrove forest (21°32′ and 22°40′ N and 88°05′ and 89° E), along the NE Coast of the Bay of Bengal. The number of definable Bacillariophyceae species exceeded Dinophyceae taxa, and the total number of bloom-forming species declined from a maximum of ten in 2000 and a minimum of two in 2007. Blooms of the diatom Coscinodiscus radiatus were common in 2000 and 2007. Tide cycles and the onset of the monsoon season played important roles in diurnal and seasonal variability of phytoplankton. Phytoplankton biovolume showed seasonality, with the highest levels during post-monsoon periods and lowest levels during the monsoon period. Phytoplankton abundance was correlated to rainfall patterns, which may be altered by long-term changes in climate.  相似文献   

Inferred attenuation from site effect-correctedT phases recorded on the island of Hawaii     

S. Koyanagi  K. Aki  N. Biswas  K. Mayeda 《Pure and Applied Geophysics》1995,144(1):1-17

Coda site amplification factors are used to eliminate the site effect from records of three circum-PacificT phases recorded by the Hawaiian Volcano Observatory (HVO) network on the island of Hawaii. ObservedT-phase amplitudes across the island generally decrease with increasing distance from the conversion point where acoustic waves in the SOFAR channel become seismic waves propagating through the crust. However, the decay of the observedT-phase signal across the island is not regular in regions of dense station coverage, in particular, the Kilauea caldera region. We divide the maximum observedT-phase amplitudes at a given station by the coda site amplification factor obtained for the same station and frequency band (3.0Hz); the distribution of these amplitudes reveals a smooth pattern over the entire island. The distance over which the site effect-correctedT-phase amplitude decreases by one-half, combined with the apparent velocity of propagation ofT phases across the island, allows for an approximate determination of near-surfaceQ over much of the island of Hawaii. We found a region of lowQ in the Kilauea summit area (Q≈30) and east rift zone (Q≈60) with considerably higherQ in the Kaoiki and northern portions of the island (Q≈150 to 200). The lowQ values obtained in the Kilauea summit region and east rift zone are significantly lower than estimates of codaQ in the same region, suggestingT phases may be sampling the earth's near-surface properties.  相似文献   

An electromagnetic prospecting instrument for subsurface conducting zones     

Dharmajit G. Sarma  Sakti K. Biswas 《Pure and Applied Geophysics》1965,62(1):124-128

Summary A portable electromagnetic prospecting unit comprising a transmitter, receiver and resolver, designed and constructed to operate with a vertical setup of coils at a single frequency of 1250 cps, measures the components of the magnetic field at the receiver station resolved in phase and at quadrature with field near the transmitter. This may be used to locate vertical or steeply dipping conductors down to a depth of about 0.6 times the maximum workable transmitter receiver separation of 120 meters, the accuracy of measurements of the resolved components being better than 2%. The variation of resolved components over a buried conductor indicates its position and depth.This paper is published by the kind permission of the Director General, Geological Survey of India.  相似文献