Highly heterogeneous Precambrian basement under the central Deccan Traps, India: Direct evidence from xenoliths in dykes   总被引：1，自引：0，他引：1  

Ranjini Ray  Anil D. Shukla  Hetu C. Sheth  Jyotiranjan S. Ray  Raymond A. Duraiswami  Loyc Vanderkluysen  Chandramohan S. Rautela  Jyotirmoy Mallik 《Gondwana Research》2008,13(3):375-385

Crustal or mantle xenoliths are not common in evolved, tholeiitic flood basalts that cover huge areas of the Precambrian shields. Yet, the occasional occurrences provide the most direct and unequivocal evidence on basement composition. Few xenolith occurrences are known from the Deccan Traps, India, and inferences about the Deccan basement have necessarily depended on geophysical studies and geochemistry of Deccan lavas and intrusions. Here, we report two basalt dykes (Rajmane and Talwade dykes) from the central Deccan Traps that are extremely rich in crustal xenoliths of great lithological variety (gneisses, quartzites, granite mylonite, felsic granulite, carbonate rock, tuff). Because the dykes are parallel and only 4 km apart, and only a few kilometres long, the xenoliths provide clear evidence for high small-scale lithological heterogeneity and strong tectonic deformation in the Precambrian Indian crust beneath. Measured ⁸⁷Sr/⁸⁶Sr ratios in the xenoliths range from 0.70935 (carbonate) to 0.78479 (granite mylonite). The Rajmane dyke sampled away from any of the xenoliths shows a present-day ⁸⁷Sr/⁸⁶Sr ratio of 0.70465 and initial (at 66 Ma) ratio of 0.70445. The dyke is subalkalic and fairly evolved (Mg No. = 44.1) and broadly similar in its Sr-isotopic and elemental composition to some of the lavas of the Mahabaleshwar Formation. The xenoliths are comparable lithologically and geochemically to basement rocks from the Archaean Dharwar craton forming much of southern India. As several lines of evidence suggest, the Dharwar craton may extend at least 350–400 km north under the Deccan lava cover. This is significant for Precambrian crustal evolution of India besides continental reconstructions.  相似文献   

Remote sensing and GIS application for land quality assessment for coffee growing areas of Karnataka   总被引：2，自引：0，他引：2  

G. M. Shalima Devi  K. S. Anil Kumar 《Journal of the Indian Society of Remote Sensing》2008,36(1):89-97

An assessment of land quality was carried out for coffee-growing areas of Karnataka using satellite image, toposheets and soil studies. The investigation focused on monitoring soil processes that control the land quality using satellite data in order to identify the land qualities that are ideal for coffee-growing; to identify the status of land qualities of coffee-growing areas using satellite imageries, toposheets and soil resource maps and to characterise land quality using soil studies in selected areas. The land quality was characterised using climatic data, terrain analysis and soil attributes. From the study it was observed that coffee growing lands of Gabbugal and Kelagur have best land qualities and coffee-growing areas of Balur and Nellikkad have moderate land qualities. Satellite image and aerial photographs were successfully used for monitoring the land quality and its changes in these areas. For optimum utilization of available natural resources on a sustainable basis, timely and reliable information on soils regarding their nature, extent and spatial distribution along with their potential and limitations is very important. The efficiency and accuracy of data are improved when remote sensing data products such as aerial photographs and satellite image are used.  相似文献   

Rice-acreage estimation for Orrisa using remotely sensed data     

S. Panigrahy  J. S. Parihar  N. K. Patel  V. K. Dadhwal  T. T. Medhavy  B. K. Ghose  N. Ravi  K. C. Pani  B. K. Panigrahy  V. N. Sridhar  R. R. Mohanty  S. K. Nanda  D. P. Tripathy  P. K. Mishra  H. P. Bhatt  S. R. Oza  S. Sudhakar  K. S. Sudha  P. Kumar  N. K. Das 《Journal of the Indian Society of Remote Sensing》1991,19(1):17-26

Rice is one of the most important foodgrains grown in India. Attempts have been made to estimate kharif rice acreage of Orissa state since 1986 using digital remote sensing data from Landsat MSS/TM and/or IRS-1A. Accuracies of the estimates obtained have been evaluated against BES (Bureau of Economics and Statistics) estimate. This paper describes the methodology adopted for rice acreage estimation of Orissa state, the results obtained for three years, i.e. 1986–87, 1988–89 and 1989–90, and their accuracy.  相似文献   

Inelastic seismic response of one-storey,asymmetric-plan systems: Effects of system parameters and yielding     

Rakesh K. Goel  Anil K. Chopra 《地震工程与结构动力学》1991,20(3):201-222

The inelastic response of one-storey, asymmetric-plan systems to two excitations is presented and analysed with the objective of identifying the influence of system parameters: uncoupled lateral vibration period, uncoupled torsional-to-lateral frequency ratio, stiffness eccentricity, relative values of the strength and stiffness eccentricities, and yield factor. Furthermore, the influence of yielding on the response of asymmetric-plan systems is examined. In particular, we determine whether the well known relationship between the response of yielding and elastic single-degree-of-freedom (SDF) systems is also applicable to asymmetric-plan systems.  相似文献   

Evaluation of shale gas reservoir in Barakar and barren measures formations of north and south Karanpura Coalfields,Jharkhand     

V. A. Mendhe  Alka D. Kamble  Mollika Bannerjee  Subhashree Mishra  Sabita Mukherjee  Parashar Mishra 《Journal of the Geological Society of India》2016,88(3):305-316

India recognizes the strategic importance for developing shale gas resources like other countries in the world. Shale gas reservoirs are known to be difficult for extracting gas in comparison to conventional reservoirs. Recently, due to high prices of gas, rising demand and enhancement in recovery technologies has attracted the Indian energy industries to explore the shale gas resource. Coal and lignite are the prime source of energy in India and these resources are well explored, while shale is ignored, despite it being associated with coal and lignite bearing formations. The paper presents reservoir characteristics of shale horizons in Barren Measures and Barakar formations of north and south Karanpura coalfields. Shale core samples were collected from exploratory boreholes in air tight canisters. In-situ gas content and adsorption capacities ascertained to be 0.51–1.69 m³/t and 3.90–5.82 m³/trespectively. Desorbed gas derived from canisters contains CH₄, C₂H₆, C₃H₈, CO₂, N₂ and O₂ and varies from 76.19–82.63, 0.38–0.76, 0.10–0.50, 8.65–12.34, 9.89–19.34 and 0.56–2.24 vol. % respectively. The permeability and porosity determined under reservoir simulated confining pressure is varying from 0.41–0.75 mD and 0.89–2.28 % respectively. The plots of Rock Eval S₂vs TOC and HI against Calc. VRo% indicates that all shale samples belong to Type III kerogen, which is prone to generate gas. It is evaluated that insitu gas content, sorption capacity, saturation level and low permeability of shale beds are critical parameters for development of shale gas resource in the studied area.  相似文献   

Dispersion of methane in tailgate of a retreating longwall mine: a computational fluid dynamics study     

Devi Prasad Mishra  Pradeep Kumar  Durga Charan Panigrahi 《Environmental Earth Sciences》2016,75(6):475

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Intercomparison of High-Resolution Bay of Bengal Circulation Models Forced with Different Winds     

Atul Srivastava  Suneet Dwivedi  Alok Kumar Mishra 《Marine Geodesy》2016,39(3-4):271-289

The high-resolution Bay of Bengal circulation modeling in the region [80E–95E; 5N–22N] is performed with a horizontal resolution of 10 km and the highest vertical resolution of 5 m near the surface. The intercomparison experiments, with ocean model forced with the near-surface (1) National Centers for Environmental Prediction (NCEP) reanalysis winds and (2) blended seawinds data (a combination of remotely sensed scatterometer and in situ observations) are carried out for a period of 17 years during 1998–2014. The seasonal variability of the realistically simulated surface hydrographic (temperature and salinity) and circulation (currents) variables from both the experiments is compared and contrasted with the observational data. The mixed layer depth seasonal variability of the region is also studied. The mesoscale features of currents at 50 and 100 m are also studied. The volume transport across different sections in the Bay of Bengal is computed and its relation with summer monsoon rainfall is investigated. The results suggest that there is no real advantage of using high-resolution blended seawinds over the much coarser NCEP reanalysis winds.  相似文献   

Monitoring Tamil Nadu flood of 2015 using satellite remote sensing     

Anoop Kumar Mishra 《Natural Hazards》2016,82(2):1431-1434

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Cyclone and monsoonal wave characteristics of northwestern Bay of Bengal: long-term observations and modeling     

Sisir Kumar Patra  Pravakar Mishra  P. K. Mohanty  U. K. Pradhan  U. S. Panda  M. V. Ramana Murthy  V. Sanil Kumar  T. M. Balakrishnan Nair 《Natural Hazards》2016,81(2):1051-1071

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Crustal structure in the North Arabian Sea from magnetic surveys     

D. C. Mishra 《Marine Geophysical Researches》1981,4(4):427-436

The spectral study of the aero-magnetic map of the North Arabian Sea (above 20°N) has delineated three horizons at average depths of 45 km, 21 km, and 8 km. Spectral estimates from smaller blocks of data drawn from the original map suggest that the 21 km horizon varies in depth from 14 km on the abyssal plain (oceanic crust) to 24 km towards the north and 28 km towards the east onto the continental shelf. This appears to correspond to the crust-mantle interface (Moho). The 8 km horizon corresponds to the top of the igneous basement. The significance of the deepest layer (45 km) is discussed as the maximum depth of the Curie point geotherm in this region. The spectral estimate of the block of data on the continental shelf off the west coast of India (above 20°N) has brought out some magnetic inhomogeneity at a shallower depth of 4 km. This appears to be connected with the sea-floor spreading phenomenon from the Carlsberg ridge. The presence of such a magnetic inhomogeneity at a depth of 4 km is further confirmed by the spectral estimate of a marine magnetic map off the west coast of India around Bombay. The depth of the basement inferred from this study is in close agreement with that obtained from other studies in this region, such as seismics.  相似文献