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1.
Dilip K Mukhopadhyay Bidyut K Bhadra Tamal K Ghosh Deepak C Srivastava 《Journal of Earth System Science》1996,105(2):157-171
Numerous peraluminous and porphyritic granitic bodies and augen gneisses of granitic compositions occur in the nappe sequences
of the Lower Himalaya. They are Proterozoic-to-lower Paleozoic in age and have been grouped into the ‘Lesser Himalaya granite
belt’. The mode of emplacement and tectonic significance of these granites are as yet uncertain but they are generally considered
to be sheet-like intrusions into the surrounding rocks. The small and isolated granite body (the Chur granite) that crops
out around the Chur peak in the Himachal Himalaya is one of the more famous of these granites. Several lines of evidence have
been adduced to show that the Chur granite has a thrust (the Chur thrust) contact with the underlying metasedimentary sequence
(locally called the Jutogh Group). The Chur granite with restricted occurrence at the highest topographic and structural levels
represents an erosional remnant of a much larger sub-horizontal thrust sheet. The contact relations between the country rocks
and many of the other granite and granitic augen gneisses in the Lesser Himalaya belt are apparently similar to that of the
Chur granite suggesting that at least some of them may also represent thrust sheets. 相似文献
2.
A numerical technique for delineation of soil mapping units using multi-spectral remote sensing data
Ravinder Kaur S K Bhadra M Bhavanarayana B C Panda 《Journal of the Indian Society of Remote Sensing》1998,26(4):149-160
A numerical technique for transformation of ground based sail spectral information into soil mapping — unit information, in terms of the total information content index has been proposed. The study carried out on 14 surface soil samples. widely differing in their physical appearance of colour and collected from different parts of India, revealed that total information content index could distinctly discriminate between the contrasting soil physiographic units with black cotton, red and sandy soil types. A comparison of the proposed index with the conventionally used two or three waveband specific indices (e.g. NIR/Red and NIR-Red/Red-Green) showed that the proposed index was more characteristic of the various soil types studied. Further, unlike the conventional 2-D indices, the proposed, numerical technique lead to the complete compression of the information contained in the entire reflectance spectrum (irrespective of the number of wavebands) to a single characteristic value in 1-D Space and a simplified 1-D clustering analysis. 相似文献
3.
A. Bhadra 《Astrophysics and Space Science》2007,310(1-2):169-172
Scalar tensor (ST) theories of gravitation contain an attractor mechanism towards general relativity. The mechanism is supposed
to start back at time of inflation. Consequently the characteristic coupling function of the ST theories could attain a very
large value during the radiation epoch. Here ST cosmology in the radiation dominated universe is studied under such situation.
A general solution of the scale factor in the radiation dominated flat universe is obtained that is characterized by an additional
degree of freedom. An implication of this extra parameter is discussed.
相似文献
4.
B. K. Bhadra A. K. Gupta J. R. Sharma 《Journal of the Geological Society of India》2009,73(2):273-288
Detailed studies on the status of Saraswati Nadi of northern Haryana have been carried out using multi date and multi resolution
satellite images, GIS techniques and ground data. Palaeochannels have been delineated using remote sensing techniques and
validated using discovered archaeological sites, sedimentological data from drilled wells and water quality data. Detailed
analysis of hydrological data (rainfall and stream discharge), catchment area and petrographic analysis of rock samples have
been done to decipher the dwindling state of Saraswati Nadi. Likelihood of Adi Badri as the place of origin of Saraswati Nadi
and its possible linkage with the Vedic Saraswati River is discussed. Suggestions have been given for safeguarding and revival
of Saraswati Nadi as a national heritage. 相似文献
5.
Syed Mohammad Saalim R. Saraswat T. Suokhrie S. R. Bhadra S. R. Kurtarkar R. Nigam 《Environmental Earth Sciences》2017,76(20):706
Being sensitive to environmental changes, foraminifera have been extensively used to monitor pollution level in the marine environment, including the effect of mining in coastal areas. In the Goa state of India, the rejects from opencast mining on land largely find their way to the estuaries, as washout during monsoon. Additionally, the Mormugao Port at the mouth of the Zuari estuary is the hub of activities due to the transport of ore from hinterland areas by barges and its subsequent loading for export. On the directive of the Supreme Court of India, all the mining-related activities abruptly stopped throughout India, including that in Goa in 2012, and got reinstated in 2015. Therefore, it provided a fit case to test the effectiveness of benthic foraminifera as an indicator of environmental impact due to mining activities. A total of ten surface sediment samples from five locations in Zuari estuary were collected from a depth range of 4.5–8.5 m in the years of 2013 and 2016 and were analyzed for both the living (stained) and dead benthic foraminifera. The year 2013 represents a time interval immediately after the closure of extensive mining activity, and the sampling during 2016 represents minimal mining. The living benthic foraminiferal abundance was higher (19–54/g sediment) during 2013 and decreased substantially during 2016 (3–22/g sediment), suggesting an adverse effect of activities associated with mine closure on benthic foraminifera. Additionally, the relative abundance of Ammonia was also significantly low during the year 2016. The temporal variation in dead foraminifera was, however, different than that of the living foraminifera. The differential response was attributed to the terrigenous dilution as a result of change in sedimentation rate. Therefore, we conclude that living foraminifera correctly incorporate the changes in mining pattern and may be used as an effective tool to monitor the impact of mining. We further suggest that the potential counter effect of terrigenous dilution on total and living benthic foraminiferal population should be considered while interpreting temporal variations in foraminiferal abundance in marginal marine settings. 相似文献
6.
Groundwater levels in hard-rock areas in India have shown very large declines in the recent past. The situation is becoming more critical due to a paucity of rainfall, limited surface water resources and an increasing pattern of groundwater extraction in these areas. Consequently, the Ground Water Department with the aid of World Bank has implemented the water structuring programme to mitigate groundwater scarcity and to develop a viable solution for sustainable development in the region. The present study has been undertaken to assess the impact of artificial groundwater recharge structures in the hard-rock area of Rajasthan, India. In this study groundwater level data (pre-monsoon and post-monsoon) of 85 dug-wells are used, spread over an area of 413.59 km2. The weathered and fractured gneissic basement rocks act as major aquifer in the area. Spatial maps for pre- and post-monsoon groundwater levels were prepared using the kriging interpolation technique with best fitted semi-variogram models (Spherical, Exponential and Gaussian). The groundwater recharge is calculated spatially using the water level fluctuation method. The entire study period (2004–2011) is divided into pre- (2004–2008) and post-intervention (2009–2011) periods. Based on the identical nature of total monsoon rainfall, two combinations of average (2007 and 2009) and more than average (2006 and 2010) rainfall years are selected from the pre- and post-intervention periods for further comparisons. All of the water harvesting structures are grouped into the following categories: as anicuts (masonry overflow structure); percolation tanks; subsurface barriers; and renovation of earthen ponds/nadis. A buffer of 100 m around the intervention site is taken for assessing the influence of these structures on groundwater recharge. The relationship between the monsoon rainfall and groundwater recharge is fitted by power and exponential functions for the periods of 2004–2008 and 2008–2011 with R 2 values of 0.95 and 0.98, respectively. The average groundwater recharge is found to be 18% of total monsoon rainfall prior to intervention and it became 28% during the post-intervention period. About 70.9% (293.43 km2) of the area during average rainfall and more than 95% (396.26 km2) of the area during above-average rainfalls show an increase in groundwater recharge after construction of water harvesting structures. The groundwater recharge pattern indicates a positive impact within the vicinity of intervention sites during both average and above-average rainfall. The anicuts are found to be the most effective recharge structures during periods of above-average rainfall, while subsurface barriers are responded well during average rainfall periods. In the hard-rock terrain, water harvesting structures produce significant increases in groundwater recharge. The geo-spatial techniques that are used are effective for evaluating the response of different artificial groundwater recharge techniques. 相似文献
7.
B.K. Bhadra 《Gondwana Research》2000,3(3)
In the eastern part of southern Peninsular India, the charnockitic hills of the Madras block are cut across by the E-W trending Attur shear zone (ASZ) which is characterised by a thick (1 to 1.5 km) phyllonite zone, showing intense mylonitisation due to ductile shearing. Steeply plunging (70°–80°) stretching lineation on steeply dipping mylonitic foliation within this zone indicates a relative vertical upliftment of the adjacent blocks. A dextral shearing event from west to east is envisaged from the kinematic analysis of shear sense indicators such as S-C fabric, asymmetric folds, asymmetric augens and asymmetric porphyroclasts. Simultaneous development of these features, related to vertical and horizontal movements may be explained by the mechanism of transpressional deformation. The Attur shear zone may be correlated with the Moyar shear zone based on distinct lithological and structural similarities. 相似文献
8.
Massif type anorthosites at Bolangir, eastern India are emplaced at the vicinity of the proto-Indian craton—Eastern Ghats Granulite belt contact. Micro- and meso-structural evidences indicate that the emplacement of the anorthosite pluton and the adjoining granitoids was syn-tectonic with respect to the D3 deformation phase (950–1,000 Ma) in the host gneiss. Anisotropy of magnetic susceptibility confirms that magnetic fabrics within anorthosite were dominantly developed during D3 deformation. Emplacement of felsic melts in the N-S trending dilatant shear zones in the granitoids, Fe-Ti-Zr-REE rich melt bands along N-S trending shear zones and localized N-S magnetic foliation in anorthosite near the Fe-Ti-Zr-REE rich melt bands indicate change in the stress field from NNW-SSE (D3) to E-W (D4). Available geochronological and paleogeographic data coupled with the structural analyses of the intrusive and the host gneiss indicate that the emplacement of massif type anorthosite in the EGP is not related to the accretion of Eastern Ghats Granulite Belt over proto-Indian continent during late Neoproterozoic. 相似文献
9.
Surface samples (Ap horizon) of twenty one soils widely differing in their physical appearance of colour were collected from different parts of India. Air-dried soils, passed through 2 mm sieve, were packed in black round trays for reflectance measurements. Soil colour of air-dry soils was designated using Munsell colour charts. Spectral reflectance patterns were obtained by a portable spectroradiometer using sunlight as the illuminant. For each sample, the XYZ tristimulus values; x,y chromaticity coordinates were obtained from reflectance patterns using the CIE standard methods. Munsell. notations were also converted to tristimulus and chromaticity coordinates using published tables of Wyszecki and Stiles (1982). The RGB colour coordinates obtained from both the systems were compared. The RGB values from spectral data were well correlated with reflectance in TM bands, while those from Munsell notation were correlated to a lesser extent. The tristimulus values were used to designate each soil with specific set of values to locate them in Universal Colour Space. 相似文献
10.
In the Ranmal migmatite complex, non-anatectic foliated graniteprotoliths can be traced to polyphase migmatites. Structural–microtexturalrelations and thermobarometry indicate that syn-deformationalsegregation–crystallization of in situ stromatic and diatexiteleucosomes occurred at 800°C and 8 kbar. The protolith,the neosome, and the mesosome comprise quartz, K-feldspar, plagioclase,hornblende, biotite, sphene, apatite, zircon, and ilmenite,but the modal mineralogy differs widely. The protolith compositionis straddled by element abundances in the leucosome and themesosome. The leucosomes are characterized by lower CaO, FeO+MgO,mg-number, TiO2 , P2O5 , Rb, Zr and total rare earth elements(REE), and higher SiO2 , K2O, Ba and Sr than the protolith andthe mesosome, whereas Na2O and Al2O3 abundances are similar.The protolith and the mesosome have negative Eu anomalies, butprotolith-normalized abundances of REE-depleted leucosomes showpositive Eu anomalies. The congruent melting reaction for leucosomeproduction is inferred to be 0·325 quartz+0·288K-feldspar+0·32 plagioclase+0·05 biotite+0·014hornblende+0·001 apatite+0·001 zircon+0·002sphene=melt. Based on the reaction, large ion lithophile element,REE and Zr abundances in model melts computed using dynamicmelting approached the measured element abundances in leucosomesfor >0·5 mass fraction of unsegregated melts withinthe mesosome. Disequilibrium-accommodated dynamic melting andequilibrium crystallization of melts led to uniform plagioclasecomposition in migmatites and REE depletion in leucosome. KEY WORDS: migmatite; REE; trace element; partial melting; P–T conditions 相似文献