Bulk organic δ13C and C/N ratios as palaeosalinity indicators within a Scottish isolation basin     

Elizabeth A. V. Mackie  Melanie J. Leng  Jeremy M. Lloyd  Carol Arrowsmith 《第四纪科学杂志》2005,20(4):303-312

Microfossils in isolation basin sediments are frequently used to reconstruct sea‐level change, but preservation problems and non‐analogue situations can limit their usefulness. Here we investigate the potential of stable carbon isotopes (δ¹³C) and C/N ratios from bulk organic matter, as an alternative proxy of salinity within isolation basin sediments from a basin in northwest Scotland. Within the Holocene sediment δ¹³C and C/N are determined largely by the mean weighted values of the predominant source of the organic material. Analysis of modern materials and comparison with the diatom record shows that the marine parts of the sequence are dominated by high δ¹³C and variable C/N. In the fresh water sequences the organic material is a mixture of both freshwater aquatic and terrestrial plant input that have relatively low δ¹³C and high C/N. The application of δ¹³C and C/N ratios in the studied basin in general follow the environmental change recorded by the diatoms and shows the potential of bulk organic matter in the investigation of salinity change in isolation basins. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Emission lines and optical continuum in low-luminosity radio galaxies     

K. A. Wills  R. Morganti  C. N. Tadhunter  T. G. Robinson  M. Villar-Martin 《Monthly notices of the Royal Astronomical Society》2004,347(3):771-786

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GEOGRAPHY IN CANADA     

J. Lewis Robinson 《The Professional geographer》1986,38(4):411-417

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A review of data processing in the earth sciences in Canada     

S. C. Robinson 《Mathematical Geology》1970,2(4):377-397

Much effort is presently being given in Canada to the development of a national system for storage and retrieval of geologic data. Coordination of these efforts is directed by the secretariat of the National Institute for Geoscience Data under guidance of the Geological Survey of Canada. Most files are project oriented but archival files are justified for data whose observations cannot be repeated, such as those for mineral deposits. Presently, extensive file systems have been created for storage of information obtained in petroleum exploration and exploitation, mineral deposits, field mapping, and geochemistry and geophysics. A Canadian Index to Geoscience Data has been prepared and contains references to all maps and reports, published or unpublished, data banks, and all documents on open file for the federal and provincial agencies.SAFRAS, a general, self-adaptive free-format retrieval and storage system, is employed to retrieve data in plain language. Although geologists are using data systems, it will be the coming generation of geologists who will make maximum use of data processing in geology.presented to the Geological Society of Washington, 8 December 1969.  相似文献   

Clumpy Langmuir waves in type III radio sources     

P. A. Robinson 《Solar physics》1992,139(1):147-163

A model is developed for the clumpy Langmuir waves observed in type III source regions. In this model the waves are generated by instability of a beam which propagates outward from the Sun in a state close to marginal stability. Ambient density perturbations cause fluctuations about the marginally stable state, leading to nonuniformities in both beam and waves and, hence, to spatially inhomogeneous growth. High damping rates and high wave levels are strongly anti-correlated, leading to suppression of the net damping. Below saturation stochastic growth causes the waves to follow a random walk in the logarithm of their energy density and the resulting probability of observing a field of magnitude E is approximately proportional to E ^-1. Comparison with observations shows that this model can account for the levels and clumpiness of the Langmuir waves, the small net dissipation required for the beams to propagate to 1 AU, the characteristic decay time of type III electromagnetic emission, and the negative mean growth rate observed in situ in type III sources. At 1 AU only the very highest fields approach the threshold for nonlinear wave collapse, but this threshold may be more commonly exceeded closer to the Sun.  相似文献   

TRENDS IN LATIN AMERICANIST GEOGRAPHY IN THE UNITED STATES AND CANADA     

David J. Robinson  Brian K. Long 《The Professional geographer》1989,41(3):304-314

The question of what lies ahead is of particular concern for Latin Americanists. The last decade has witnessed a serious erosion of both the popularity of their specialty, and an equally troublesome reduction in employment opportunities. This paper uses Association of American Geographers (AAG) data bases to document the age-gender structure of contemporary Latin Americanist geographers, and projects likely compositional changes through the end of the century.  相似文献   

A study of type V solar radio bursts     

R. D. Robinson 《Solar physics》1978,56(2):405-416

A model for the solar Type V event is developed. This model assumes that the basic difference between Type III and Type V bursts is the evolution of the electron beam. For a Type V this beam rapidly elongates, so that it takes progressively longer times to pass higher plasma levels. Physical process influencing the beam development, including Coulomb collisions, non-linear interactions with Langmuir waves and wave-particle scattering from various hydromagnetic wave modes is discussed. The model is compared with previously derived models and with observations.Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation.  相似文献   

Observations of the infrared triplet of singly ionized calcium     

Jeffrey L. Linsky  Richard G. Teske  Carol W. Wilkinson 《Solar physics》1970,11(3):374-383

Observations are presented of the Caii infrared triplet (8498 Å, 8542 Å, and 8662 Å) at three positions on the solar disk to make possible direct analyses of the lines and comparisons with theoretical computations. The source functions for the two strongest lines (8542 Å and 8662 Å) are equal at those heights corresponding to the wings of the lines (¦¦ > 0.4 Å) but not to those of the cores. We suggest that the apparent source function inequality in the cores is due to limb darkening caused by inhomogeneities in the chromosphere.Of the National Bureau of Standards and University of Colorado.  相似文献   

Mode coupling due to twisting of magnetic field lines     

D. B. Melrose  P. A. Robinson  T. M. Feletto 《Solar physics》1995,158(1):139-158

A new approach to the theory of mode coupling in an inhomogeneous, birefringent medium is used to treat mode coupling in a magnetized plasma with a twisted magnetic field. The twist introduces a resonance, corresponding to the rate of twisting being equal to the rate of generalized Faraday rotation. When this resonance occurs it introduces a new regime of strong mode coupling. The implications of this regime are discussed in connection with the long-standing problem in solar radiophysics that mode coupling appears to be stronger than theory implies, but no obvious resolution of the problem is found.  相似文献   

Long-Term Behaviour of an Aftershock Sequence: The Inangahua, New Zealand, Earthquake of 1968     

Russell Robinson  Walter J. Arabasz  F. F. Evison 《Geophysical Journal International》1975,41(1):37-49

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