Occurrence of thorite and radioactive zircon in syenite pegmatite,North of Ashwaraopet,Khammam district,Andhra Pradesh,India     

K. Surya Prakash Rao  R. S. N. Sastry  Gautam Roy 《Journal of Earth System Science》1989,98(2):183-187

This paper reports the occurrence of thorite and confirms the earlier find of radioactive zircon by Subbarao, Murali and others from syenite pegmatite in the Vinayakapuram-Kunavaram alkaline belt in the Khammam district of Andhra Pradesh, India. Thorite has also been found as residual concentrations in soil overlying the pegmatite.  相似文献   

Use of remote sensing in lineament analysis for tectonic evolution and resource study of a part of Vindhyan Basin,Jhalawar area,India     

S. M. Ramasamy  P. C. Bakliwal  K. L. V. Ramana Rao 《Journal of the Indian Society of Remote Sensing》1988,16(1):63-71

Synoptivity and the exemplified fracture systems exhibited by the space borne imagery data has helped in solving many of the geological enigma in various parts of the world. The study conducted, using such remotly sensed data, in Jhalawar anticline, part of Proterozoic Cratonic Vindhyan Basin, Rajasthan, India, led to infer the history of tectonic evolution of peribasinal deformation which has been a matter of controversy for a century and more. In Landsat MSS data the Jhalawar region displays a panorama of lineaments and their analysis through azimuthal frequency diagrams, isofracture, lineament incidence and lineament intersection incidence density maps shows that the mean orientation of the lineaments fall in NW-SE and NE-SW and the shape of the various lineament density contours also show NE-SW and NW-SE orientations. In aerial photographs the area exhibits four sets of lineaments in NE-SW, NW-SE, N-S and E-W directions. Amongst these the former two sets are expressed as wide open master fracture systems with prolific vegetation fills along them and the latter two sets are characteristically observed as thin vegetation linears with frequent strike slip faulting along them. The further analysis of these fracture/lineament systems derived from multi-level remote sensing data shows that the Jhalawar anticline, which followed the pattern of flexural slip fold mechanism, was evolved by horizontally disposed σ1 (greatest principal stress) and 3σ (least principal stress) with the former oriented in NE-SW and the latter aligned in NW-SE directions with vertically disposed 2σ. The inference of such palaeostress environment of the Jhalawar region lead in the identification of a buried rigid basement high southwest of Jhalawar anticline, beneath the Deccan pile and loci of ground water, silica sand and probable igneous plug.  相似文献   

Random-walk model studies of the transport and diffusion of pollutants in katabatic flows     

Ashok K. Luhar  K. Shankar Rao 《Boundary-Layer Meteorology》1993,66(4):395-412

The flow and turbulence quantities governing dispersion in katabatic flows vary with both height and downslope distance. This variation cannot be accounted for in conventional plume dispersion models. In this study, three random-walk models of varying complexity are formulated to simulate dispersion in katabatic flows, and their strengths and weaknesses are discussed. The flow and turbulence parameters required by these models are determined from a high-resolution two-dimensional katabatic flow model based on a turbulent kinetic energy closure. Random-walk model calculations have been performed for several values of source height and slope angle to examine the influence of these parameters on dispersion. Finally, we simulated the perfluorocarbon and heavy methane tracer releases for Night 4 of the 1980 ASCOT field study over a nearly two-dimensional slope in Anderson Creek Valley, California. The observed peak concentrations are generally well-predicted. The effects of the pooling of the drainage air could not be taken into account in our katabatic flow model and, consequently, the predicted concentrations decay much more rapidly with time than the observed values.  相似文献   

On the crosscorrelation between drought indices and solar activity     

G. Padmanabhan  A. Ramachandra Rao 《Theoretical and Applied Climatology》1990,41(1-2):55-61

Summary Crosscorrelation structure between solar activity and drought indices is investigated by analyzing the cross correlation of the residual time series of solar activity and drought indices. Double Sunspot Cycle, Zürich Sunspot number, Palmer's Drought Index and Drought Area Index data are used in the study. White residual series derived from the observed data series by using valid time series models are used for the crosscorrelation analysis. Weak correlations between solar activity and drought area indices are inferred. The lags of significant correlation appear to vary for the different time series used in the study.With 3 Figures  相似文献   

地球化学计算中误差传递分析的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

徐伟彪  饶纪龙 《地质科学》1990,(2):187

 通过两个实例讨论了地球化学计算中的误差传递问题,对照了四种不同方法的潜力和限制,拓广了蒙特卡洛方法在相关变量分析中的应用,指出其在不同条件下总能用有限机时逼近合理结果,揭示出协方差矩阵法的特殊效益,可相对于独立初始变量展现中间变量的相关关系。  相似文献   

地球化学计算中误差传递分析的应用          下载免费PDF全文

徐伟彪  饶纪龙 《地质科学》1990,(2):187-193

通过两个实例讨论了地球化学计算中的误差传递问题,对照了四种不同方法的潜力和限制,拓广了蒙特卡洛方法在相关变量分析中的应用,指出其在不同条件下总能用有限机时逼近合理结果,揭示出协方差矩阵法的特殊效益,可相对于独立初始变量展现中间变量的相关关系。  相似文献   

Applications of Error Propagation Analyses to Geochemical Calculation     

徐伟彪  饶纪龙 《中国地球化学学报》1991,10(2):166-173

Two examples are given for comparing applications and limitations of four methods which can be used to deal with error propagation in geochemical calculations.The examples indicate that the Monte Carlo method can also be employed to evaluate the effect of covariance.A special function of the method for covariance matrix shown here can reveal the correlations of middle variables relative to the independent primary variables.  相似文献   

Geochemistry of the Baishitouquan Amazonite—and Topaz—bearing Granite in the Mid—Tianshan Belt,Xinjiang,China     

Gu Lianxing  Yang Hao  Gou Xiaoqin  Guo Jichun  Wang Jinzhu 《中国地球化学学报》1994,13(4):289-304

The Baishitouquan amazonite and topaz-bearing granite is one of the typical high-rubidium and high-fluorine granites in the eastern part of the Mid-Tianshan belt. This intrusion is in sharp contact with Mid-Proterozoic schists, gneisses and marbles, and is composed of four zones transitional from the bottom upwards: leucogranite, amazonite granite, topaz-bearing amazonite granite and topaz quartz albitite. The Baishitouquan granite contains highly ordered K-feldspar, Li-rich mica, Mn-rich garnet, α-quartz and low temperature zircon and is chemically high in Si, K, Na, Al, Li, Rb, Cs and F, and low in Ti, Fe, Ca, Mg, P, Co, Ni, Cr, V, Sr and Ba, with Na₂O<K₂O. Amazonite from the amazonite granite zone contains 1867 ppm Rb. The F contents of bulk rocks are 3040 and 4597 for the amazonite granite and topaz-bearing amazonite granite zones, respectively. These two zones have δ¹⁸O values of 8.97–9.85‰ (SMOW) and show flat REE distribution patterns with strong Eu depletion. K-Ar and Rb-Sr ages of this intrusion are 226. 6 Ma and 209. 6 Ma respectively, with an initial⁸⁷Sr/⁸⁶Sr ratio of 0.987±0.213. The Baishitouquan granite is the product of crystallization of a low temperature, and water, rubidium and fluorine-rich magma, which may have been derived from partial melting of muscovite-rich crustal rocks. Consolidation of this granite involved two contrasting and successive stages: melt crystallization and hydrothermal metasomatism and precipitation. Various geological features of this granite were formed during the transition from the magmatic to the hydrothermal stage.  相似文献   

A two-stage evolution of Visakhapatnam-Paradip shelf,east coast of India,from magnetic studies     

A S Subrahmanyam  K S R Murphy  T C S Rao  M M Malleswara Rao  S Lakshminarayana  K Venkateswarlu 《Journal of Earth System Science》1994,103(1):17-26

A detailed analysis of bathymetry and magnetic data of Visakhapatnam-Paradip shelf, east coast of India revealed three major structural lineaments over the shelf/slope of the area. Models derived from the anomalies associated with the trends indicate that trend A represents horst and graben type continental basement while trend B is due to a series of dyke intrusions. Trend C off Chilka lake forms the northward extension of 85°E lineation from deep sea Bengal Fan. A two stage evolution of the eastern continental margin of India has been inferred from the study of this part of the margin, viz., the rift stage evidenced by dyke intrusions of reverse polarity located within the inner part of the shelf and post-rift stage characterized by vertical tectonics in the form of a horst and graben type continental basement. The hotspot related aseismic 85°E ridge further complicated the tectonics of this part of the area.  相似文献   

The atmospheric heat source over the Bolivian plateau for a mean January   总被引：2，自引：0，他引：2  

Gandikota V. Rao  Suat Erdogan 《Boundary-Layer Meteorology》1989,46(1-2):13-33

The atmospheric heat sources of large plateaus strongly influence the general circulation particularly in the summer season. The Bolivian plateau and the adjacent areas affect the upper tropospheric flow in a typical summer month by developing an anticyclone and deflecting the prevailing westerlies. The plateau initially warms the atmosphere through sensible heating and then through latent heating as thunderstorms develop.The atmospheric heat source over the Bolivian and adjacent plateau was computed employing conventional surface and satellite radiation data for the mean January 1979. Because of a lack of direct ground temperature data, the surface radiation was estimated following an empirical formula devised for some earlier Tibetan studies.The results revealed that the latent heating developing in the eastern and northeastern part of the plateau is the biggest contributor to the atmospheric heat source (500 W m^-2). A comparison of these results against similar recent results from Tibet showed that the atmospheric heat source in South America is stronger than that over Tibet, primarily because of increased rainfall over Bolivia.  相似文献