Distribution of elements between coexisting phengite and chlorite from the greenschist facies of the Tennant Creek area,Central Australia     

T. Ramamohana Rao 《Lithos》1977,10(2):103-112

The Lower Proterozoic Warramunga Group of the Tennant Creek area consists essentially of slates, phyllites and greywackes. ‘Porphyroidal’ rocks of pyroclastic origin, consisting of quartz porphyry and quartz-feldspar porphyry, form conformable horizons within the Warramunga Group and both show the same structural evolution. Recrystallization of phengite and chlorite in the Warramunga rocks was synchronous with regional folding and took place under greenschist facies conditions. Recrystallization of groundmass matrix into phengite and chlorite in the ‘porphyroidal’ rocks also took place under greenschist facies conditions during regional deformation. The major elements in coexisting phengite and chlorite from these groups were analysed in 14 samples by electron microprobe. Total analyses of 6 rocks were carried out by X-ray fluorescence spectrograph. Distribution of Mg and Fe²⁺ between coexisting phengite and chlorite shows a vague linear trend. The distribution coefficient K_D(Mg) is influenced in part by X_Mg of phengite. The tie lines for the mineral pairs on the triangular diagram show a subparallel trend. The Mg/Mg + Fe²⁺ of chlorite varies sympathetically with the Mg/Mg + Fe²⁺ of the rock.  相似文献   

Interpretation and analysis of multispectral data for aricultural crop cover types-role of crop spectral response and crop sectral signature     

R. S. Ayyangar  M. V. Krishna Rao  K. R. Rao 《Journal of the Indian Society of Remote Sensing》1980,8(2):39-48

Airborne multispectral data obtained over mono and multiple cropping systems of small farming agriculture was studied for two cropping seasons for a possible development of crop spectral signatures and to utilize such signatures for interpretation of multispectral data and for assessing agricultural potentials of a region. In multiple cropping system, the unique crop spectral response exhibited by crop species at specific growth stages facilitated interpretation and analysis of multispectral data with the knowledge of crop phenology. For resolving spectral confusion between crop species due to growtn stages of different crop species, temporal data were observed to be useful. Development and use of crop spectral sigrature for interpretation and analysis multispectral data related to mono cropping system were found to be relatively less complex and offer great promise because of minimum spectral confusion.  相似文献   

Moisture relationships for the Southern Hemisphere     

Nandamudi Jagan Mohana Rao  Y. Viswanadham  G. S. S. Nunes 《Pure and Applied Geophysics》1980,118(2):1076-1089

Values for mean precipitable water are computed for four seasons of the year and for different regions of the Southern Hemisphere. Relationships between surface dew-point temperature and precipitable water were studied for these regions. A harmonic analysis of our data on precipitable water is attempted. Out results are presented and discussed.  相似文献   

Magnetic study of the dolerite dyke near Amarpur,Dhanbad (Bihar)     

Jagdeo Singh  M. Krishna Rao 《Pure and Applied Geophysics》1970,82(1):133-148

Summary The dolerite dyke of post-lower Gondwana age reported earlier by the authors [5]²) has been taken for detailed magnetic study. Seven magnetic traverses have been taken across the dyke using Schmidt vertical force variometer. Negative anomalies varying from 1400 to 2200 gammas have been observed. Magnetic susceptibility of samples from the dyke has been determined on both cores and crushed material, using the Model MS-3 susceptibility bridge. The average susceptibility of 20 samples has been found to be 1930x10^–6 C.G.S. units. Direction and intensity of remanence on 10 oriented samples have been determined by an Astatic magnetometer. The average intensity of remanence has been found to be 3.13x10^–3 C.G.S. units and the average direction has a declination of 323° and inclination-68° (up dip). The Koenigsberger ratio varies from 1.6 to 5.6. The high negative magnetic anomalies have been explained in terms of remance-that more than 80% of the anomaly is due to remance and that negative anomalies are due to negative inclination of remanent direction of the rocks. The magnetic direction for the dyke gave the position for Dhanbad as 51° south latitude in Jurassic period. This is in conformity with the deductions made by other workers from the palaeomagnetic studies of the Deccan and Rajmahal traps. The virtual geomagnetic pole in Jurassic period as deduced from the palaeomagnetism of the dyke has a position of latitude 8 1/2°N and longitude 71°W, in the southern Carribean. On palaeomagnetic evidence this dyke has been correlated with Rajmahal traps of eastern Bihar.  相似文献   

A gradient method for interpreting magnetic anomalies due to horizontal circular cylinders,infinite dykes and vertical steps   总被引：2，自引：0，他引：2  

I. V. Radhakrishna Murthy  C. Visweswara Rao  G. Gopala Krishna 《Journal of Earth System Science》1980,89(1):31-42

A new method of interpreting magnetic anomalies of arbitrarily-magnetised horizontal circular cylinders, dipping dykes and vertical steps is presented. The method makes use of both horizontal and vertical gradients of the magnetic field of the model under consideration, rather than the observed magnetic anomaly. Vertical and horizontal gradients are calculated from the observed anomalies, and plotted one against the other to find out the locus of tip of the resultant gradient vector. This locus is a symmetrical curve for each of the three models mentioned above. The properties of these curves are used to deduce the various parameters of these models and the direction of magnetisation.  相似文献   

Clay mineralogy of the late pleistocene red sediments of the Visakhapatnam region,east coast of India     

N.V.N. Durgaprasada Rao  Y. Srihari 《Sedimentary Geology》1980,27(3):213-227

The fine-fraction mineralogy of the red sediments and of the upland soils along the Visakhapatnam—Bhimunipatnam coastal region has been studied by X-ray analysis. Dominant kaolinite with subordinate illite is the general clay-mineral assemblage in both the red sediments and the soils. The similar clay-mineral composition indicates that the upland soils are the source for the clay material in the red sediments. Montmorillonite is present in some samples and shows greater abundance in the red sediments than in the soils. The additional montmorillonite is considered to have been formed by post-depositional diagenesis in the red sediments at the expense of illite. Differences in the intensity of the weathering process controlled by the gradient in the source area have been suggested as being responsible for the variation in type and abundance of the clay minerals in the red sediments. It is inferred that humid and tropical to subtropical climatic conditions prevailed and persisted throughout the Late Pleistocene and Holocene in the Visakhapatnam region.  相似文献   

Generation of spectrum compatible accelerograms     

R. Narayana Iyengar  P. Narasimha Rao 《地震工程与结构动力学》1979,7(3):253-263

In this paper a new method is presented for generating earthquake accelerograms which have pre-established response spectra. The non-stationary random nature and other salient features of the accelerograms can be taken care of by the procedure developed. The method leads to a sample spectrum which lies above the given spectrum. The generation of records to suit several spectra simultaneously can also be handled by this approach. The method is detailed first. This is followed by several numerical examples.  相似文献   

The inelastic vibration absorber subjected to earthquake ground motions     

K. S. Jagadish  B. K. Raghu Prasad  P. Vasudeva Rao 《地震工程与结构动力学》1979,7(4):317-326

Two storey bilinear hysteretic structures have been studied with a view to exploring the possibility of using the dynamic vibration absorber concept in earthquake-resistant design. The response of the lower storey has been optimized for the Taft 1952, S69°E accelerogram with reference to parameters such as frequency ratio, yield strength ratio and mass ratio. The influence of viscous damping has also been examined.  相似文献   

Water and energy use efficiencies of native grasslands in the arid regions of India     

G. G. S. N. Rao  A. S. R. A. S. Sastri 《Theoretical and Applied Climatology》1982,31(1-2):127-132

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Toxicity of Phenol,Pentachlorophenol and Sodium Pentachlorophenolate to a Freshwater Teleost Lebistes reticulatus (Peters)     

P. K. Gupta  V. S. Mujumdar  P. S. Rao  V. S. Durve 《洁净——土壤、空气、水》1982,10(2):177-181

Lebistes reticulatus (Peters) was exposed to various concentrations of phenol, pentachlorophenol and sodium pentachlorophenolate to determine their toxicity, lethal concentrations and slope functions by a static bioassay procedure. Simultaneous controls were also run. The 94h LC₅₀ values were 47.5mg/l (42.04 … 53.68) for phenol, 0.77 mg/l (0.616 … 0.963) for sodium pentachlorophenate and 0.97 mg/l (0.866 … 1.086) for pentachlorophenol. On this basis, the rank order is sodium pentachlorophenolate-pentachlorophenol-phenol. During the treatment, fish showed an abnormal swimming reflex, excessive mucus secretion, haemorrhage near lips, abdomen and basis of fins and loss of equilibrium followed by death.  相似文献