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41.
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
42.
Prosenjit Ghosh S. K. Bhattacharya Ashok Sahni R. K. Kar D. M. Mohabey K. Ambwani 《Cretaceous Research》2003,24(6):743-750
A single locality of the Late Cretaceous (Maastrichtian) Lameta Formation at Pisdura in Central India has yielded a large number of coprolites attributed to titanosaurian dinosaurs. Internally the coprolites are dark grey and contain abundant plant tissues and other organic materials. The plant tissues are mostly of gymnospermous origin. In addition, remains of bacterial colonies, fungal spores and algae are seen in the macerated fraction under scanning electron microscope. The dark grey appearance is probably attributable to fine-grained organic matter within voids in tracheids or xylem. The average 13C/12C ratio of the organic matter in the coprolites is -24‰ (relative to PDB) suggesting that plants of C3type were the main diet of their producers. A comparison of δ15N value (about 4‰ w.r.t. air) of the coprolites with that of faecal matter of modern herbivores and carnivores suggests that gut fermentation may not have been an active mechanism in the digestion process of titanosaurs. 相似文献
43.
Haimanti Biswas Mitali Dey Dipnarayan Ganguly Tarun K. De Sandip Ghosh Tapan K. Jana 《Estuaries and Coasts》2010,33(2):395-398
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
44.
The dispersion relation for magnetosonic waves within the upper atmospheric plasma has been derived. The result can be used to study the variation of the longitudinal and transverse component of velocities. 相似文献
45.
46.
Shamik Ghosh Pankaj Jain Gopal Kashyap Rahul Kothari Sharvari Nadkarni-Ghosh Prabhakar Tiwari 《Journal of Astrophysics and Astronomy》2016,37(4):25
There currently exist many observations which are not consistent with the cosmological principle. We review these observations with a particular emphasis on those relevant for the Square Kilometre Array (SKA). In particular, several different data sets indicate a preferred direction pointing approximately towards the Virgo cluster. We also observe a hemispherical anisotropy in the Cosmic Microwave Background radiation (CMB) temperature fluctuations. Although these inconsistencies may be attributed to systematic effects, there remains the possibility that they indicate new physics and various theories have been proposed to explain them. One possibility, which we discuss in this review, is the generation of perturbation modes during the early pre-inflationary epoch, when the Universe may not obey the cosmological principle. Better measurements will provide better constraints on these theories. In particular, we propose measurement of the dipole in number counts, sky brightness, polarized flux and polarization orientations of radio sources. We also suggest test of alignment of linear polarizations of sources as a function of their relative separation. Finally we propose measurement of hemispherical anisotropy or equivalently dipole modulation in radio sources. 相似文献
47.
Tapan Pal Biswajit Ghosh Anindya Bhattacharya S. K. Bhaduri 《Journal of Earth System Science》2010,119(1):19-25
The bedded felsic tuff exposed in Rutland Island, Andaman, consists of two facies:
– |
white massive tuff with ill-defined bedding contacts (facies-A) and 相似文献
48.
Nonlinear kinetic analysis of phenol adsorption onto peat soil 总被引:1,自引:0,他引:1
Phenolic compounds are considered as a serious organic pollutant containing in many industrial effluents particularly vulnerable when the plant discharge is disposed on land. In the present study, the phenol removal potential of peat soil as adsorption media was investigated as the adsorption process are gaining popular for polishing treatment of toxic materials in industrial wastewater. Batch experiments were performed in the laboratory to determine the adsorption isotherms of initial concentrations for 5, 8, 10, 15, and 20 mg/L and predetermined quantity of peat soil with size ranges between 425 and 200 μm poured into different containers. The effects of various parameters like initial phenol concentration, adsorbent quantity, pH, and contact time were also investigated. From experimental results, it was found that 42 % of phenol removal took place with optimized initial phenol concentration of 10 mg/L, adsorbent dose of 200 g/L, solution pH 6.0 for the equilibrium contact time of 6 h. The result exhibits that pseudo-first-order (R 2 = 0.99) and Langmuir isotherm models are fitted reasonably (R 2 = 0.91). Adams–Bohart, Thomas, Yoon–Nelson, and Wolborska models were also investigated to the column experimental data of different bed heights to predict the breakthrough curves and to determine the kinetic coefficient of the models using nonlinear regression analysis. It was found that the Thomas model is the best fitted model to predict the experimental breakthrough curves with the highest coefficient of determination, R 2 = 0.99 and lowest root mean square error and mean absolute performance error values. 相似文献
49.
Analysing the spatio-temporal evolution of an active debris slide in Eastern Himalaya,India 总被引:1,自引:0,他引:1
Saibal Ghosh Anjan Bora Sudipta Nath Ashok Kumar 《Journal of the Geological Society of India》2014,84(3):292-302
Landslide is one of the prominent geohazards in the Himalayas where loss of lives and property are common. Owing to the complicated geomorphic and tectono-stratigraphic setting of this active Fold-thrust belt (FTB), landsliding of all possible types and spatial scales observed exhibit conspicuous spatio-temporal signatures and evolution. This evolution of landslides is commonly studied by regional assessment and by examining the multi-temporal landslide inventories of a particular area. The success of creating such multi-temporal landslide inventory depends on (i) the availability of relevant past source data (e.g., images, post event maps, air photos etc.) of suitable resolution, scale and quality, (ii) time of generation of source data with respect to the time of landsliding event, (iii) skill of the investigators in interpreting the old images, air photos etc. However, this method is of restricted use in studying the spatio-temporal evolution of a single landslide which is perennially active in the Himalayan terrain, where rapid changes in land use and land cover patterns readily obliterate the signatures of past landsliding. Moreover because of scale constraints, subtle and frequent changes in the spatial dimensions of these individual landslides, and their temporal activity become difficult to identify in such regional assessment carried out over a larger area. In this study therefore, a different approach is adopted whereby the spatio-temporal activity and style of Lanta Khola landslide, a perennially active and large (0.25 km2) debris flow in the Eastern Himalayas, has been studied in detail through detailed scale (1:1000) site-specific geological mapping in phases during the last 28 years (1983–2011). Such site-specific geological observations coupled with numerical slope stability analysis utilising the limit equilibrium method facilitate in detailed understanding of the temporal and spatial evolution and inherent mechanism of this perennial landslide. 相似文献
50.
Contrasting Signals of Glacier Changes in Zanskar Valley,Jammu & Kashmir,India Using Remote Sensing and GIS 总被引:1,自引:0,他引:1
Swagata Ghosh A. C. Pandey M. S. Nathawat I. M. Bahuguna Ajai 《Journal of the Indian Society of Remote Sensing》2014,42(4):817-827
The study of advancement and recession of the glaciers in the Himalayas is essential due to their contrasting response towards climatic change. In the present study, Survey of India (SOI) topographical maps of 1962, IRS: LISS-III image of 2001 and LANDSAT-5: TM (Thematic Mapper) image of 2009 were used to analyze the glacier fluctuations in a part of Zanskar valley. The analysis carried out on 212 glaciers indicated decrease of 57 km2 (8 %) of glacier area over many glacier which was partly compensated with area increase by 42 km2 (6 %) in other glaciers, resulting an overall glacier area decrease by only 15 km2 (2 %) from 1962–2001. Due to glacier fragmentation the number of glaciers increased from 212 in 1962 to 238 by 2001. Although majority of glaciers (88 %) exhibited retreat (up to 13 my?1), minor advancement (<15 my?1) also took place in few glaciers during this period. Advancement took place mainly in larger glaciers (2–5 km2 and >5 km2) located over wider altitudinal range (700 m–1,000 m) whereas smaller glaciers (<2 km2) with narrow altitudinal range (100 m–500 m) exhibited retreat. The supraglacial debris analysis indicated that percentage of debris cover over glaciers ranges from 1.43 % to 18.15 %. Smaller glaciers (<2 km2) were debris free in comparison to the larger glaciers (>5 km2). During 2001–2009 majority of the glaciers were apparently stable in terms of their area and snout position indicating less impact of climate forcing in parts of Zanskar valley as compared to other parts of the Himalaya. 相似文献
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