A method for rapid evaluation of magnetic anomalies over thin sheets     

H. V. Ram Babu  D. Atchuta Rao 《Pure and Applied Geophysics》1983,121(2):327-337

A method for rapid evaluation of magnetic anomalies over thin sheets is presented. This method is based on characteristic distancesX _3/4,X _1/2,X _1/4 at which the anomaly falls off to 3/4, 1/2, and 1/4 of the total (peak to peak) amplitude, respectively. Simple mathematical relations using these characteristic distances are presented to estimate the death and dip of the sheet. This method is fast and does not require prior knowledge of the base level and the origin. A few field examples are included to show the applicability and efficacy of the method.  相似文献   

A study of the vertical magnetic anomaly caused by magnetite deposits in Sua area of Palamau district,Bihar (India)     

C. L. Singh  Avadh Ram 《Pure and Applied Geophysics》1971,85(1):283-289

Summary A magnetic survey carried out in Sua area of the Palamau district, Bihar (India) has shown very interesting anomalies. The survey has been conducted specially to obtain the extension of the magnetite deposits which are being quarried at Sua. The interpretation of magnetic anomalies have clearly brought out the following facts: a) the magnetite is extending both sides of the quarry to a considerable distance, b) the nature of the anomaly indicates that the magnetite occurs in the form of veins. It has also been possible to find out the thickness of the veins and the depth at which they occur.  相似文献   

The organic analysis of the murchison meteorite   总被引：1，自引：0，他引：1  

Ram L. Levy  Michael A. Grayson  Clarence J. Wolf 《Geochimica et cosmochimica acta》1973,37(3):467-483

The organic compounds released from the Murchison carbonaceous chondrite following vaporization-pyrolysis at 150, 300 and 430°C were investigated. The total organic yield was 272 ppm and consisted of n-alkanes, alkenes, aromatic hydrocarbons and thioaromatics. The composition and yield at all three temperatures are compared with those obtained by an identical analysis on another carbonaceous chondrite, Allende, and two terrestrial rocks.Comparison of compounds released by 150°C volatilization of Murchison and Allende reveals remarkable similarities, suggesting commonality in the processes responsible for their formation. The origin of the organic compounds found can be explained in terms of the Fischer-Tropsch synthesis followed by partial equilibration of the primary products. However, problems concerning the relationship between types of carbonaceous chondrites remain unresolved.  相似文献   

Circulation and fertility of waters in Concepcion Bay     

Ahumada B. Ramón  Rudolph G. Anny  Martinez M. Victorino 《Estuarine, Coastal and Shelf Science》1983,16(1):95-105

The spatial and temporal distributions of oxygen, nutrients and pigments in the waters of Concepcion Bay, Chile (36°40′S, 73°01′W) are described for 1978–1979. Analysis of the seasonal fluctuations shows the upwelling of water poor in oxygen and rich in nutrients inside the bay during summer. The upwelled water fertilizes the bay and produces progressive eutrophication, causing mass mortalities, discoloured water and mineralization of organic matter.  相似文献   

Mercury in sediments of Ulhas estuary   总被引：5，自引：0，他引：5  

Ram A  Rokade MA  Borole DV  Zingde MD 《Marine pollution bulletin》2003,46(7):846-857

Hg levels in water, suspended particulate matter and sediment of the Ulhas estuary are under considerable environmental stress due to the indiscriminate release of effluents from a variety of industries including chlor-alkali plants. Concentration ranges of dissolved (0.04-0.61 micro gl(-1)) and particulate (1.13-6.43 micro gg(-1)) Hg reveal a definite enhancement of levels in the estuary. The Hg burden in sediment upstream of the weir that limits the tidal influence is low (0.08-0.19 micro gg(-1)) with low C(org) content (1.8-2.9%). The high Hg content of the sediment just below the weir varies seasonally (highest concentration recorded being 38.45 micro gg(-1)) due to incremental accretion of sediment as the fresh water flow over the weir progressively decreases. The 30 km segment of the estuary sustains markedly high levels of Hg in the sediment with an exponential decrease in the seaward direction from the weir. Higher concentrations than the expected background prevail in all the estuarine cores up to the bottom, though the overall concentration decreases from about 20 micro gg(-1) in core 7 (inner estuary) to 1 micro gg(-1) in core 31 (outer estuary). The Hg in sediment is associated with C(org), while its correlation with Al, Fe and Mn is poor. The Hg profiles in cores from the Arabian Sea (stations 34, 35 and 37) have a distinct horizon of enhanced concentration in the 5-60 cm segment. Based on 210Pb dating of core 37, the sediment at the bottom of this core is inferred to have been deposited in the year 1949, roughly two year prior to the establishment of the first chlor-alkali plant and represents the background (0.06-0.10 micro gg(-1)). The Hg profiles in the offshore cores indicate a marked increase in transfer of Hg to sediment subsequent to 1980, with a peak around 1990-1992. Based on the index of geoaccumulation it is considered that the estuarine segment between stations 4 and 23 is extremely polluted, while the sediment from the open coast is moderately polluted in the top 25-30 cm with respect to Hg. The enrichment factor of Hg in the sediment is 350-700 for core 4 and decreases to 0-7 for the open-shore cores.  相似文献   

Mass functions of five distant northern open star clusters     

Ram Sagar  & W. K. Griffiths 《Monthly notices of the Royal Astronomical Society》1998,299(3):777-788

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Deformational and crystallization history of the Precambrian rocks in north-central Aravalli Mountain,Rajasthan, India     

Ram S. Sharma 《Precambrian Research》1977,4(2):133-162

Large-scale structures, textures and mineral assemblages in the Precambrian rocks of the Banded Gneissic Complex and the overlying Delhi Group in north-central Aravalli Mountain reveal a complex deformational-crystallization history. In the basement Gneissic Complex at least three deformational events, D₀, D₁ and D₂, and two separate episodes of metamorphism, M₁ and M₂, are recognized. The supracrustal Delhi Rocks display only two phases of deformation, D₁ and D₂, associated with a single protracted period of metamorphism, M₂.The first phase of deformation (D₁) of the Delhi orogeny (1650-900 m.y.) produced large isoclinal folds that are overturned towards the southeast and have gentle plunges in NE and SW directions. The second phase of deformation (D₂) gave rise to tight open folds on the limbs and axial-plane surfaces of the D₁ folds. These folds generally plunge towards the N and NNW at 30°–80°. In the Basement Complex one more deformation (D₀) of the Pre-Delhi orogeny (> 2000 m.y.) is recorded by the presence of reclined and recumbent folds with W to WNW trending fold axes. The D₀ folds were superimposed by D₁ and D₂ folds during the Delhi orogeny.The three deformational events have been correlated with the crystallization periods of minerals in the rocks and a setting in time is established for this part of the Aravalli range.  相似文献   

Concurrent Use of OSCAT and AltiKa to Characterize Antarctic Ice Surface Features     

Kamaljit Singh Rajkumar  Megha Maheshwari  Jayaprasad Pallipad  Dhani Ram Rajak  Raj Kumar 《Marine Geodesy》2015,38(3):497-509

Radar altimetry provides an important geophysical parameter, backscatter coefficient (σ₀), which is useful in studying target surface characteristics. Ku-band (Oceansat-2 scatterometer- OSCAT) and Ka-band (SARAL-AltiKa altimeter) data are concurrently used to characterize polar surface features over the Antarctic region. Maximum-likelihood classification has been employed to classify combined data set (AltiKa and OSCAT) for discrimination among sea ice, open water, and ice sheet (interior and exterior). The sea ice region obtained using the current approach has been compared with sea ice boundary derived from passive microwave data.  相似文献   

Links between teleconnection patterns and mean temperature in Spain     

David Ríos-Cornejo  Ángel Penas  Ramón Álvarez-Esteban  Sara del Río 《Theoretical and Applied Climatology》2015,122(1-2):1-18

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Role of selected riparian herbs in reducing soil erosion and nutrient loss under simulated rainfall   总被引：3，自引：2，他引：1  

Nishant Kumar Srivastava  Lal C. Ram  R. E. Masto 《Environmental Earth Sciences》2010,61(2):405-417

The native riparian herbs such as Leonotis nepetaefolia (L.) R. Br., Cassia tora L., Ageratum conyzoides L., Parthenium hysterophorus L. and Sida acuta burm f., dominant on the bank of River Damodar in Eastern Jharia Area, Dhanbad (India), were selected to assess experimentally their quantitative role in conserving the soil and reducing water runoff and nutrient (N and P) losses. A total of 42.5 mm simulated rainfall were applied at 30 cm h⁻¹ rain intensity on both vegetated and bare plots. The collected runoff water and eroded soil from each plot were determined in terms of soil, water and nutrient conservation value (CV). Among the vegetated plots, soil CV ranged from 30 to 85% and water CV from 20 to 48%. Nutrient (N and P) CV varied from 22 to 65% for total-N, 48 to 80% for ammonia-N and 50 to 86% for nitrate-N. CV for total-P varied from 40 to 62%, inorganic-P from 42 to 60% and organic-P from 20 to 58%. In a stepwise multiple regression equation comprising four independent variables (canopy cover, litter mass, soil moisture and plant biomass), canopy cover explained 70–88% (P < 0.01) of variability in conserving soil, water and nutrient. The losses through runoff water and eroded soil from vegetated plots were found to be minimized to a great extent as compared to bare plots. The role of these species in maintaining the texture and fertility status of riparian soil is discussed.  相似文献