Deposition fluxes of chemical components of fog water at a rural site in north-east India   总被引：1，自引：0，他引：1  

MONIKA J. KULSHRESTHA  R. SEKAR  D. KRISHNA  A. K. HAZARIKA  N. C. DEY  P. G. RAO 《Tellus. Series B, Chemical and physical meteorology》2005,57(5):436-439

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ELECTROMAGNETIC RESPONSE OF TWO-DIMENSIONAL INHOMOGENEITIES IN A DISSIPATIVE HALF-SPACE FOR TURAM INTERPRETATION *     

A. DEY  H. F. MORRISON 《Geophysical Prospecting》1973,21(2):340-365

An integral equation technique based on the integral formulation of the electric field of a harmonically excited line-source in the presence of a two-dimensional scattering in-homogeneity is outlined. In this treatment the inhomogeneity is assumed to have an arbitrary cross-sectional shape and to be located in a layered, dissipative half-space. The scattering responses in terms of the horizontal and the vertical magnetic field components observed on the ground surface are studied for a variety of geologic models involving overburden layers, vertical or inclined veins and multiple inhomogeneities. The horizontal component of the total magnetic field appears to be the most diagnostic response parameter. A thin vein shaped target with a cross sectional area of 0.05 δ₂× 0.50 δ₂ (δ₂ being the skin-depth in the lower half-space) located 0.50 δ₂ away from the line-source and under a highly conductive overburden layer (σ₁/σ₂= 300) of thickness 0.02 δ₂ is easily detected with a moderate resolution. The scattering responses are also sensitive to changes in depths of burial, inclination and conductivity contrast with the surrounding half-space of the target inhomogeneity. An interpretation scheme as well as a number of characteristic detectability parameters are developed for the conventional Turam method used in mineral exploration.  相似文献   

The subsurface megascopic characteristics of basalt and basement rocks from Koyna-Warna area of Maharashtra,India     

D. K. Sinha  Anjan Som  Sukanta Roy 《Journal of the Geological Society of India》2017,90(6):761-768

Vertical deep boreholes of depth up to 1522.50m have been drilled in Koyna-Warna area of Maharashtra State within the Deccan Volcanic Province to study the most outstanding example of Reservoir Triggered Seismicity (RTS). The drilling of 9 bore-holes in the area has provided a window to earth scientists to peep into geological details available below Deccan Trap.The 932.50m thick pile of Deccan basalt, consisting of 30 flows at Rasati, near Koyna, which has been physically seen through cores, present a marvellous geological repository for observations. The megascopic characteristics of various flows and variation in composition have been presented in this paper. The microscopic and geochemical characteristics have been kept out of this communication, as the relevant studies are not completed to draw any conclusion. This study records the presence of granite wash (≈1m thick) over basement and below basalt representing Late Archaean to Cretaceous period hiatus. The basement rocks, presumably of Late Archaean age have been described mega-scopically. A fair picture of sub-surface pre-Deccan topography is shown with the help of borehole data, which confirm the nearly flat topography of pre-Deccan surface especially in this part of the area occupied by 30 flows of Deccan basalt. Correlation of 30 flows with the established stratigraphy has also been attempted for subsurface existence of Ambenali (Upper) and Poladpur Formations of Wai Subgroup in Koyna-Warna area.  相似文献   

Fissures and fractures in the Koyna seismogenic zone,western India     

Surajit Misra  Sukanta Roy  Vikrant Bartakke  Gaurav Athavale  Harsh Gupta 《Journal of the Geological Society of India》2017,89(2):131-132

Mn-rich ilmenites (up to 7 % MnO) have been identified in dykes cutting the Malanjkhand porphyry copper mining area in Madhya Pradesh. The dykes are hydrothermally altered and are of tholeiitic affinities. Lamprophyres have been reported from nearby areas. The presence of Mn-rich Ilmenites in the Malanjkhand copper mine dykes and the occurrence of lamprophyres and the pervasive potassium metasomatism in the area strongly suggests a possibility of finding diamondiferous rocks in the area. Such high-Mn bearing ilmenites are associated with diamondiferous deposits in other parts of the world, e.g. Juina kimberlites, Brazil. Mn-bearing ilmenite is considered as an indicator mineral for kimberlite/diamond occurrences. The presence of kimberlite pipes in Raipur district and the association of Mn-rich ilmenite with kimberlites is a fortuitous coincidence for venture-some mining companies. A probable explanation for the origin of manganese layers in the context of ‘rift’ tectonic environment is offered. Also a possible link between the dykes, quartz veins in the Malanjkhand granitic rocks and the copper mineralization is proposed.  相似文献   

Tectonic Setting of the Kadiri Schist Belt, Andhra Pradesh, India     

Sukanta GOSWAMI  Pradeep K. UPADHYAY  Purnajit BHATTACHARJEE  Malaiandi G. MURUGAN 《《地质学报》英文版》2017,91(6):1992-2006

Plate tectonic activity has played a critical role in the development of petrotectonic associations in the Kadiri schist belt. The calc alkaline association of basalt, andesite, dacite and rhyolite(BADR) is the signature volcanic rock suite of the convergent margin. The N-S belt has gone below the unconformity plane of Cuddapah sediments. In the northern part geochemical and structural attributes of the Kadiri greenstone belt is studied along with microscopic observations of selected samples. Harker diagram plots of major elements generally indicate a liquid line of descent from a common source, such that BADR rocks are derived from a common parent magma of basaltic to andesitic composition. These calc-alkaline volcanic rocks are formed at convergent margins where more silicic rocks represent more highly fractionated melt. All the litho-units of this greenstone belt indicate crush and strain effects. The stretched pebbles in the deformed volcanic matrix with tectonite development along with associated greenschist facies metamorphism, alteration and hydration is remarkable. Flow foliation plane with N-S strike and very low angle(5° to 10°) easterly dip and N-S axial planar schistosity formed due to later phase isoclinal folding can be clearly identified in the field. Basic intrusives are quite common in the surrounding area. All the observations including the field setting and geochemistry clearly demonstrate ocean-continent subduction as the tectonic environment of the study area.  相似文献