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1.
A core from the Cambay Shale Formation of the Cambay Basin, containing immature Type III organic matter, was pyrolysed at 300°C for different durations of time to different maturation levels. Fractionation effects were studied employing a three-step extraction technique after removal of the expelled pyrolysate. The extractable organic matter (EOM) obtained on extraction of the whole core is assumed to be that present in open pores, while that obtained on finely crushing the sample is assumed to be that present in closed pores. The EOM obtained from 1 cm chips is termed EOM from semi-open pores. The gross composition of the pyrolysates expelled during pyrolysis is not similar to the oils reservoired in the area, and there is no significant fractionation observed between expelled pyrolysates and unexpelled EOM. Our study indicates movement of fluids between closed, semi-open and open pores. In both systems, there is a higher concentration of EOM in open pores than in semi-open and closed pores, and the fraction of EOM in open pores is much greater in the artificial system than in the natural system. Fractionation effects on n-alkane and isoprenoid hydrocarbon-based parameters were also studied. n-Alkenes are present in semi-open and closed pores of the immature core and in the core after it was pyrolysed to 300°C for 6 and 48 h, but are absent in the open pores. n-Alkenes are present in closed pores in the naturally matured core. Presence of n-alkenes in the pyrolysates expelled during the 6 and 48 h experiments, but their absence in the open pores of the core, indicates that expulsion also occurs through temporary microfractures during laboratory pyrolysis, whereas in the natural system expulsion from closed pores seems to be only via semi-open and open pores. 相似文献
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Hydrogeology Journal - The study defines the hydrogeological framework of the Quaternary aquifer of south Bengal Basin, India, and the impact of urbanisation on the groundwater resources in and... 相似文献
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Rahul Sharma S. Jai Sankar Sudeshna Samanta A. A. Sardar D. Gracious 《Geo-Marine Letters》2010,30(6):617-626
Factors such as non-uniform illumination of seafloor photographs and partial burial of polymetallic nodules and crusts under
sediments have prevented the development of a fully automatic system for evaluating the distribution characteristics of these
minerals, necessitating the involvement of a user input. A method has been developed whereby spectral signatures of different
features are identified using a software ‘trained’ by a user, and the images are digitized for coverage estimation of nodules
and crusts. Analysis of >20,000 seafloor photographs was carried out along five camera transects covering a total distance
of 450 km at 5,100–5,300 m water depth in the Central Indian Ocean. The good positive correlation (R2 > 0.98) recorded between visual and computed estimates shows that both methods of estimation are highly reliable. The digitally
computed estimates were ∼10% higher than the visual estimates of the same photographs; the latter have a conservative operator
error, implying that computed estimates would more accurately predict a relatively high resource potential. The fact that
nodules were present in grab samples from some locations where photographs had nil nodule coverage emphasises that nodules
may not always be exposed on the seafloor and that buried nodules will also have to be accounted for during resource evaluation.
When coupled with accurate positioning/depth data and grab sampling, photographic estimates can provide detailed information
on the spatial distribution of mineral deposits, the associated substrates, and the topographic features that control their
occurrences. Such information is critical for resource modelling, the selection of mine sites, the designing of mining systems
and the planning of mining operations. 相似文献
5.
Jagadish Prasad Sahoo Pradip Kumar Pradhan 《Geotechnical and Geological Engineering》2010,28(6):889-897
An experimental investigation was undertaken to study the effects of lime-stabilized soil-cushion on the strength behavior
of expansive soil. In the present investigation, a series of laboratory tests (Unconfined compression tests and CBR tests)
were conducted on both expansive soil alone and expansive soil cushioned with lime-stabilized non-expansive cohesive soil.
Lime contents of 2, 4, 6, 8 and 10% by dry weight of cohesive non-swelling soil was used in the stabilized soil cushion. Both
expansive soil and lime stabilized soil cushion were compacted to Standard Proctor’s optimum condition with thickness ratio
2:1. Tests on cushioned expansive soils were conducted at different curing and soaking periods i.e., 7, 14, 28 and 56 days.
The test results revealed that maximum increase in strength was achieved after 14 days of curing or soaking period with 8%
of lime content. 相似文献
6.
Application of geostatistics in estimating recoverable reserves of beach sand deposit is rare. This paper made an attempt to estimate local recoverable reserves using disjunctive kriging and discrete Gaussian model considering support and information effects for a beach sand deposit located in the eastern part of India. The dependence of different selective mining unit (SMU) sizes and different production sampling strategies on the estimated tonnage, metal quantity, and the ore tonnage versus metal quantity relationships has been examined. The results of the study show that nonlinear geostatistics should be used for more precise assessment of the grade, ore tonnage, and metal quantity and their relationships, which are necessary for recoverable reserve estimation. In selective mining operation, both support and information effects have significant influence on recoverable reserve. Recoverable reserve estimation based on SMU involves estimating grade distributions of mining unit with much bigger support than the available drill core sample data. Information effect comes into picture from the real scenario where the actual grades of the blocks remain unknown even during mining. At the mining stage, discrimination of ore and waste blocks is carried out based on estimated grades of the production samples and it is likely that the blocks might be misclassified as either ore or waste and thus sent to wrong destination. Information effect modeling makes the estimation more reliable by taking care of misclassification. 相似文献
7.
Binita Pathak Arup Borgohain Pradip Kumar Bhuyan Shyam Sundar Kundu S Sudhakar Mukunda M Gogoi Toshihiko Takemura 《Journal of Earth System Science》2014,123(4):651-663
In order to examine the spatial variability of the aerosol characteristics across the Brahmaputra valley, a land campaign was conducted during late winter (February 3–March 2) 2011. Measurements of particulate matter (PM, PM10, PM2.5) and black carbon (BC) concentrations were made onboard an interior redesigned vehicle. The length of the campaign trail stretched about 700 km, covering the longitude belt of 89.97°–95.55°E and latitude belt of 26.1°–27.6°N, comprising 13 measurement locations. The valley is divided into three sectors longitudinally: western sector (R1: 89.97°–91.75°E), middle sector (R2: 92.5°–94.01°E) and eastern sector (R3: 94.63°–95.55°E). Spatial heterogeneity in aerosol distribution has been observed with higher PM10 and PM2.5 concentrations at the western and middle sectors compared to the eastern sector. The locations in the western sector are found to be rich in BC compared to the other two sectors and there is a gradual decrease in BC concentrations from west to east of the Brahmaputra valley. Two hotspots within the western and middle sectors with high PM and BC concentrations have been identified. The associated physico-optical parameters of PM reveal abundance of PM2.5 aerosols along the entire valley. High population density in the western and middle sectors, together with the contribution of remote aerosols, leads to higher anthropogenic aerosols over those regions. Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS) slightly underestimates the measured PM10 and PM2.5 at the eastern sector while the model overestimates the measurements at a number of locations in the western sector. In general, BC is underestimated by the model. The variation of BC within the campaign trail has not been adequately captured by the model leading to higher variance in the western locations as compared to the middle and eastern locations. 相似文献
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Interpolation of climate variables and temperature modeling 总被引:1,自引:0,他引:1
Sailesh Samanta Dilip Kumar Pal Debasish Lohar Babita Pal 《Theoretical and Applied Climatology》2012,107(1-2):35-45
Geographic Information Systems (GIS) and modeling are becoming powerful tools in agricultural research and natural resource management. This study proposes an empirical methodology for modeling and mapping of the monthly and annual air temperature using remote sensing and GIS techniques. The study area is Gangetic West Bengal and its neighborhood in the eastern India, where a number of weather systems occur throughout the year. Gangetic West Bengal is a region of strong heterogeneous surface with several weather disturbances. This paper also examines statistical approaches for interpolating climatic data over large regions, providing different interpolation techniques for climate variables' use in agricultural research. Three interpolation approaches, like inverse distance weighted averaging, thin-plate smoothing splines, and co-kriging are evaluated for 4°?×?4° area, covering the eastern part of India. The land use/land cover, soil texture, and digital elevation model are used as the independent variables for temperature modeling. Multiple regression analysis with standard method is used to add dependent variables into regression equation. Prediction of mean temperature for monsoon season is better than winter season. Finally standard deviation errors are evaluated after comparing the predicted temperature and observed temperature of the area. For better improvement, distance from the coastline and seasonal wind pattern are stressed to be included as independent variables. 相似文献
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