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81.
Sankar R Rajkumar M SUN Jun Gopalakrishnan A Vasanthan T M Ananthan G Trilles J P 《海洋学报(英文版)》2011,30(1):113-117
Three species,Bathynomus decemspinosus,B.doederleini and B.kensleyi (Crustacea,Isopoda,Cirolanidae),are reported for the first time from the Parangipettai coastal waters,Southeast coast of India.Several Trilasmis (Temnaspis) tridens (Cirripedia Thoracica,Lepadomorpha) were attached to the pleopods of some individuals.So,five bathynomid species are currently reported from India. 相似文献
82.
G Ja Sankar M Jagannadha Rao B S Prakasa Rao D K Jugran 《Journal of the Indian Society of Remote Sensing》2001,29(3):165-174
Hydromorphogeological studies have been carried out around Agnigundala mineralised belt (longitude 70°.39′ - 16°.51′ and latitude 16°.2′ - 16°.15′) using remote sensing IRS-IB and SPOT data for ground water exploration. Based on erosional and depositional characters of various geomorphic units like Hills (Structural and denudational) Pediment, Buried pediment, plains and valley fills have been identified in various lithologies like granite, granite gneiss, biotite schist, phyllite,. quartzite and dolomite. The acclamations of individual geomorphic units through visual interpretation are verified from field data. The groundwater potentials of the individual geomorphologic units have been evaluated to obtain a complete hvdrogcological picture of the area. The field data have further helped in quanlifying various geomorphological units with reference to their potential for ground water occurrence. 相似文献
83.
M. Sankar-Rao V. N. Lykossov E. M. Volodin A. E. Nikitin A. I. Degtiarev Kusuma G. Rao 《大气科学进展》1991,8(2):137-148
The relationships between the global general circulation and the Indian monsoon during active and break phases are investigated with the help of FGGE IIIb data.It was found that the ultralong wave component positive and negative height anomalies over Tibet are associated with active and break monsoon phases respectively. This ultralong wave component has significant effect even upto 22oN over the Indian region which is the monsoon trough region. During a monsoon break, the general circulation was found to be more turbulent in the sense that more waves become energised.It was observed that during a break, blocking prevails over the Siberian region and cold air advection takes place toward Indian region from Siberian region depressing the temperatures over the Indian region by about 1oC. During the break, the Indian region gets connected with higher latitudes by the south winds blowing from polar Soviet re-gions to the Indian region. From active to break phase the zonal component weakens by about 25% from Indian ocean area right upto Alaskan region, along the east coast of Asia. 相似文献
84.
Hydrochemical and hydrogeological studies were carried out in the groundwater of Dhaligaon refinery area, Bongaigoan district, Assam. The study revealed that the area is underlain by alluvial deposits of thickness varying from 67 to 142 meters and the groundwater occurs in unconfined alluvial formations. Transmissivity values of the formations range from 2100 to 3800 m2/day. The effluents from the refinery are disposed off into a natural drain, “Tunia nala”, which contaminates the groundwater. The effluents contain constituents like phenol, nitrite, sulphide, iron etc, which subsequently seep into the dug well zone, but the phenol concentrations get naturally attenuated during the contaminant transport to the depths below. The probable reasons leading to natural attenuation of phenol as per in-situ hydrogeological and environmental conditions have been discussed. 相似文献
85.
J. N. Pattan G. Parthiban C. Moraes R. Rajalakshmi S. Lekshmi S. Athira S. Jai Sankar 《Journal of the Geological Society of India》2016,87(1):62-68
Pumice are explosive volcanic product, occur as uncoated or coated with ferromanganese (Fe-Mn) oxide and resides in association with ferromanganese nodules on the seabed in Central Indian Ocean Basin (CIOB). The older Fe-Mn oxide coated and younger uncoated pumice clasts were leached with 6N HCl to remove Fe-Mn oxide coatings as well as the calcium carbonate present within the vesicles. The main objective of the present study is to understand the origin of these pumice by utilizing their chemical composition. Both coated and uncoated pumice samples are rhyoliteand medium K calc-alkaline series. Major, trace, rare earth elements (∑REE) concentration and chondrite-normalized REE patterns of both coated and uncoated pumice are nearly similar to each other suggesting a same source. Tectonomagmatic discrimination diagrams (Nb vs Y: Yb vs. Ta), triangular plot (TiO2-Zr-Y) and High Field Strength Element ratios (La/Ta- 25; Ta/Hf- 0.2; Nb/Ta- 9; Zr/Nb- 22 and Ba/Ta-1084) indicate volcanic arc origin. These were probably sourced from the nearest Indonesian volcanic arc and drifted to the CIOB by currents. 相似文献
86.
87.
There is a collection of about 100 years of Ca-K line spectroheliograms at the Kodaikanal Observatory (KKL) obtained on daily basis with a single instrument that can be used to study long term variations of various chromospheric features. All the Ca-K images have been digitized using specially developed digitizers with uniform and highly stable light source, high quality lens and 4k×4k format CCD camera. The digitization has been carried out in a room with controlled temperature and humidity. The digitized data are in 16-bit format with pixel resolution of 0.86 arcsec. The digitized images have been calibrated by a process that includes flat-fielding, density to intensity conversion, centering the image, and rotation of the image to make the solar north pole in the fixed direction. Then we applied correction for the limb darkening effect and also made the background in the image uniform. The image background was normalized to unity that enabled us to use the intensity contrast to identify different features, such as plages, enhanced (EN), active (AN), and quite network on images and classified them by using different image contrast and area threshold values. After several experiments with different threshold values for different features and careful analysis of a large number of images, we could fix the threshold values of intensity contrast larger than 1.35 and area larger than 1 arcmin2 for plages, larger than 1.35 but area less than 1 arcmin2 for EN, and between 1.25?–?1.35 for AN. We compared the quarterly averaged and half yearly averaged plage areas obtained from KKL with the Mount Wilson (MWO) data and sunspot number. We find that the plage area extracted from the KKL is highly correlated with the MWO plage area, though there is a slight difference between the two data set in cycle 19. The plage area of KKL is also highly correlated with the sunspot number. The areas of EN and AN are also found to have smaller quasi-periodic variations apart from the solar cycle variations. 相似文献
88.
We present the seismic source zoning of the tectonically active Greater Kashmir territory of the Northwestern Himalaya and seismicity analysis (Gutenberg-Richter parameters) and maximum credible earthquake (m max) estimation of each zone. The earthquake catalogue used in the analysis is an extensive one compiled from various sources which spans from 1907 to 2012. Five seismogenic zones were delineated, viz. Hazara-Kashmir Syntaxis, Karakorum Seismic Zone, Kohistan Seismic Zone, Nanga Parbat Syntaxis, and SE-Kashmir Seismic Zone. Then, the seismicity analysis and maximum credible earthquake estimation were carried out for each zone. The low b value (<1.0) indicates a higher stress regime in all the zones except Nanga Parbat Syntaxis Seismic Zone and SE-Kashmir Seismic Zone. The m max was estimated following three different methodologies, the fault parameter approach, convergence rates using geodetic measurements, and the probabilistic approach using the earthquake catalogue and is estimated to be M w 7.7, M w 8.5, and M w 8.1, respectively. The maximum credible earthquake (m max) estimated for each zone shows that Hazara Kashmir Syntaxis Seismic Zone has the highest m max of M w 8.1 (±0.36), which is espoused by the historical 1555 Kashmir earthquake of M w 7.6 as well as the recent 8 October 2005 Kashmir earthquake of M w 7.6. The variation in the estimated m max by the above discussed methodologies is obvious, as the definition and interpretation of the m max change with the method. Interestingly, historical archives (~900 years) do not speak of a great earthquake in this region, which is attributed to the complex and unique tectonic and geologic setup of the Kashmir Himalaya. The convergence is this part of the Himalaya is distributed not only along the main boundary faults but also along the various active out-of-sequence faults as compared to the Central Himalaya, where it is mainly adjusted along the main boundary fault. 相似文献
89.
High Mg-Al spinel-sapphirine granulites, orthopyroxene-bearing quartzofeldspathic granulites, two pyroxene-bearing mafic granulites
and metapelitic gneisses are exposed around Paderu, Eastern Ghats Belt. Geothermobarometry in orthopyroxene-bearing quartzofeldspathic
granulites and mafic granulites indicate near isobaric cooling through 90°C from ca. 720°C to 630°C, at 8.0 kbar. However,
signatures of ultrahigh temperature metamorphism are recorded from the mineralogy and reaction textures in the high Mg-Al
granulites. Mineral reactions deduced in this work, when combined with others described by Lalet al (1987) from the same area and plotted in an appropriate petrogenetic grid in the system FMASO indicate an ACW path comprising
a high dT/dP prograde arm reaching Pmax − Tmax = 9.5 kbar, ∼ 1000°C, followed by near-isobaric cooling down to 9 kbar, 900°C and subsequent decompressive reworking. 相似文献
90.
R. S. Dwivedi K. Sreenivas K. V. Ramana P. R. Reddy G. Ravi Sankar 《Journal of the Indian Society of Remote Sensing》2006,34(4):351-367
Realizing the potential of spaceborne multispectral measurements in providing spatial information on natural resources, and
of Geographic Information System (GIS) in integrating such information with the socio-economic data and other collateral information
to arrive at derivative information, we report here the results of a study which was taken up in a watershed in Charkhari
block of Mahoba district, northern India, to generate the information on natural resources from Indian Remote Sensing Satellite
(IRS-1B) Linear Imaging Self-scanning Sensor (LISS-II) images through a systematic visual interpretation, and its subsequent
integration with the collateral information in a GIS environment to develop optimal land use plan/action plan for sustainable
development of its land resources. Since permanent vegetation cover in the watershed has been dwindling due to population
pressure, the need for establishing more vegetation cover has been stressed. 相似文献