Book reviews     

Martin I. Hoffert  Eric J. Barron 《Climatic change》1981,3(3):333-335

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The late Palaeozoic Gondwana glaciation     

Prof.em. Henno Martin 《International Journal of Earth Sciences》1981,70(2):480-496

The glacial deposits of Gondwana are today spread over one whole hemisphere. On the re-assembled Gondwana continents they still occupy an area exceeding that of the Pleistocene glaciation. The onset of the glaciation in the different areas has not yet been dated satisfactorily. The earliest lower and middle Carboniferous glacial beds occur in the Andean belt and in eastern Australia, where high mountains may have existed at that time. During Stephanian-Sakmarian time, when the pole wandered over Antarctica, large ice sheets reached sealevel in all the major depositories. Palaeotopographical reconstructions allow the conclusion that some of the ice centres were supported by uplands which reached altitudes of up to 1,500 m above sealevel. Depending on their palaeotopographical positions the glacigenic sediments exhibit the full facies range to be expected between glaciated uplands and glaciomarine environments. There are indications that ice may have flowed from Africa into the Paraná Basin, and from Antarctica into the Great Karoo-Basin and into Australia. At least 12 advances and retreats have been recognized in the Paraná Basin. Closer to the ice centres the record is less complete. The retreats were probably more of an interstadial than an interglacial nature. There is some evidence that the final deglaciation proceeded in stages from South America over Africa to Antarctica. The ice centres were fed by moist air from the Pacific Ocean and the Tethys.

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Zusammenfassung Die glazialen Ablagerungen von Gondwana sind heute über eine ganze Hemisphäre verteilt. Auch auf dem rekonstruierten Gondwana nehmen sie noch ein Gebiet ein, welches das der pleistozänen Vereisung übertrifft. Die frühesten, unter- und mittelkarbonen Vereisungsspuren finden sich im Anden-Gürtel und im Tasman-Belt in Ostaustralien, wo zu dieser Zeit hohe Gebirgsketten existiert haben können. Während des Stephan und Sakmar, als der Pol sich auf der Antarktis befand, erreichten große Inlandeis-Decken den Seespiegel in allen größeren Ablagerungsbecken. Paläotopographische Rekonstruktionen erlauben die Schlußfolgerung, daß einige der Eiszentren sich auf Hochländern mit Höhen von bis zu 1500 m befanden. Die glazialen Sedimente zeigen, abhängig von ihrer paläotopographischen Position, alle zu erwartenden Faziestypen. Es gibt Hinweise, daß Eis von Afrika in das Paraná-Becken und von Antarktika in das Große Karoo-Becken und nach Australien geflossen sein könnte, Wenigstens 12 Vorstöße und Rückzüge sind im Paraná-Becken erkannt worden. In der Nähe der Eiszentren ist die Zahl geringer. Die Rückzüge hatten wahrscheinlich mehr die Natur von Interstadialen als von Interglazialen. Es gibt Hinweise, daß das finale Abschmelzen im unteren Perm in mehreren Phasen von Südamerika über Afrika nach Antarktika fortgeschritten sein könnte. Die Eiszentren wurden durch feuchte Luftmassen vom Pazifischen Ozean und der Tethys genährt.

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Résumé Les dépôts glaciaires de Gondwana sont répartis actuellement sur une hémisphère entière. Même sur le Gondwana reconstitué, ils occupent encore une surface qui dépasse celle de la glaciation pleistocène. Les traces de glaciation les plus précoces, èo- et mésocarbonifères se trouvent dans la ceinture andine et dans la ceinture tasmanienne d'Australie orientale, où des chaînes de montagnes élevées ont pu exister à cette époque. Pendant le Stéphanien et le Sakmarien, lorsque le pôle s'est trouvé dans l'Antarctique, de grandes nappes continentales de glace ont atteint le niveau de la mer dans tous les grands bassins sédimentaires. Des reconstitutions paléotopographiques permettent de conclure que quelques-uns des centres de glaciation se trouvaient dans des zones de montagnes ayant des altitudes atteignant 1500 m. Les sédiments glaciaires montrent, en fonction de leur position paléotopographique, tous les types de faciès que l'on peut attendre. D'après certaines indications, la glace aurait pu couler d'Afrique dans le bassin du Paraná et de l'Antarctique dans le grand bassin du Karoo et vers l'Australie. Au moins douze avancées et retraits ont été reconnus dans le bassins du Paraná. A proximité des centres de glaciation leur nombre est moindre. Les retraits avaient sans doute un caractère plus interstadiaire qu'interglaciaire. Certaines indications permettent de penser que la fusion finale pouvrait avoir progressé, au cours du Permien inférieur, d'Amérique du Sud vers l'Afrique puis vers l'Antarctique, en plusieurs phases. Les centres de glaciation ont été nourris par des masses d'air humides venant de l'Ocean Pacifique et de la Téthys.

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Geomorphology and landuse of Pasighat-Jonai bazar area-A photo based study in a part of Dihang river basin,Arunachal pradesh and Assam     

K. K. Sinha  A. U. Khan 《Journal of the Indian Society of Remote Sensing》1981,9(2):21-26

Photo-interpretation coupled with systematic field checks over an area of about 1500 sq. km has led to the identification of various landform units and their characteristic landuse pattern in part of the submontaneous tract of Arunachal Pradesh and Assam in the Dihang river basin. Four major geomorphic units have been mapped and their respective lithounits are studied in detail. Present landuse and the land’s capability inrespect of each of the major geomorphic units have been noted. Suggestions have been made for better utilisation of land.  相似文献   

The hydrogen and carbon isotopic composition of methane from natural gases of various origins   总被引：1，自引：0，他引：1  

Martin Schoell 《Geochimica et cosmochimica acta》1980,44(5):649-661

The deuterium concentrations (δD vs SMOW) of biogenic methanes from world-wide occurrences range from ?180 to ?280%. and were found to be depleted in deuterium by approx. 160%. compared to the deuterium concentration of their associated waters. Theoretical considerations support this relationship to be the result of bacterial transformation of CO₂ to methane and is therefore indicative of the biogenic origin of methane.Thermogenic gases with high C₂₊ concentrations (wet gases associated with crude oil) have D/H ratios from ?260 to ?150%. with deuterium contents tending to increase with decreasing wetness. Dry gases which are not associated with petroleum are more enriched in deuterium (?180 to ?130%.) and show an increase in deuterium with increasing rank of the source beds as it is similarly known for carbon-13.Many dry gases in young sedimentary basins were found to contain significant amounts of C₂₊ hydrocarbons. These gases cannot be grouped with either the biogenic or thermogenic gases and their methane is concluded to be of mixed biogenic and thermochemical origin.Using a $\text{δ}{}^{13}\text{C}\text{δD}$ diagrammatic display of the isotope data of methanes the various genetic groups of natural gases can be defined more clearly.  相似文献   

Rare earth geochemistry of fused ophiolitic and alpine lherzolites     

Martin Menzies  Douglas Blanchard  Joyce Brannon  Randy Korotev 《Contributions to Mineralogy and Petrology》1977,64(1):53-74

Partial fusion hypotheses have been proposed for the origin of lherzolite-harzburgite alpine peridotite associations. Analyzed lherzolites from Othris, Ronda, Lanzo and Beni Bouchera, have light REE depleted to chondritic REE abundances, and clinopyroxenes contain most of the REE relative to depleted olivine and orthopyroxene. Variation in the level of REE enrichment within these lherzolites indicates mantle heterogeneity probably caused by partial melting processes. The Beni Bouchera spinel lherzolite and the Othris plagioclase lherzolite are the best candidates for relatively undepleted mantle based on REE studies. Fractional fusion calculations (15–25%) reveal that partial melts have REE characteristics somewhat similar to oceanic tholeiites. Conversely, computed source peridotites from oceanic tholeiites (Schilling, 1975) are similar to the alpine lherzolites reported here. Alpine lherzolites are, however, depleted in trace elements (K, Rb, Sr and Ba, Menzies and Murthy 1976). Since the lherzolites have an undepleted major, minor and REE chemistry close to that of pyrolite, the lost trace element-rich fraction must represent a small degree of melting. It is proposed that alpine lherzolites are residue left after the loss of a nephelinitic/alkalic fraction, ([Ce/Yb]_N=2.0–4.01) representing a small degree of partial fusion. This labile fraction may have existed as an intergranular phase or hydrous mineral prior to melting.  相似文献   

On the efficiency with which aerosol particles of radius larger than 0.1 μm are collected by simple ice crystal plates     

J. J. Martin  P. K. Wang  H. R. Pruppacher  A. E. Hamielec 《Pure and Applied Geophysics》1980,118(2):1109-1129

A theoretical model is presented which allows computing the efficiency with which aerosol particles of radius 0.1r10 m are collected by simple ice crystal plates of radius 50a _c 640 m in air of various relative humidities, temperatures and pressures. Particle capture due to thermophoresis, diffusiophoresis and inertial impaction are considered. It is shown that the capture efficiency of an ice crystal in considerably affected by phoretic effects in the range 0.1r1 m. For aerosol particles ofr>1 m the efficiency is strongly controlled by the flow field around the crystal and the density of the aerosol material. Trajectory analysis also predicts that aerosol particles are preferentially captured by the ice crystal rim. Our theoretica results are found to agree satisfactorily with the laboratory studies presently available. Comparison shows that for the same pressure, temperature and relative humidity of the ambient air ice crystal plates are better aerosol particle scavengers than water drops.  相似文献   

On the error introduced into Stokes' formula by applying the Honkasalo tidal gravity term     

Martin Ekman 《Journal of Geodesy》1980,54(4):528-530

The error caused by using the Honkasalo tidal gravity term in geoid computations with Stokes' formula is discussed. It is pointed out that the relatively large value of the error to a great extent is generated by interaction between the Honkasalo term and the weight function in Stokes' formula.  相似文献   

A note on visual interpretation of landsat imagery to locate possible locust habitat in a part of Rajasthan     

P. P. Sinha 《Journal of the Indian Society of Remote Sensing》1980,8(2):7-10

Visual interpretation of Landsat data from an area in Rajasthan desert has been used to delineate vegetation and other associated parameters helpful for locust breeding and development. The results indicate the usefulness of Landsat in date locust surveys by reducing time and cost involved.  相似文献   

The Evolving Earth : L.R.M. Cocks (editor) Brit. Museum (Nat. Hist.). Cambridge Univ. Press, Cambridge, 1981, VII + 264 pp., £stg 30.00 (Hardcover),  stg. 10.50 (softcover)     

Martin Schwarzbach 《Tectonophysics》1982,86(4):403-404

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A scheme for computing surface fluxes from mean flow observations   总被引：3，自引：0，他引：3  

Martin I. Hoffert  Joel Storch 《Boundary-Layer Meteorology》1979,17(4):429-442

A computational scheme is developed for estimating turbulent surface stress, sensible heat flux and humidity flux from mean velocity, temperature and humidity at a single height in the atmospheric surface layer; conditions at this reference level are presumed known from observations or from a numerical atmospheric circulation model. The method is based on coupling a Monin-Obukhov similarity profile to a force-restore formulation for the evolution of surface soil temperature to yield the local values of shear stress, heat flux and surface temperature. A self-contained formulation is presented including parameterizations for solar and infrared radiant flux at the surface.In addition to reference-level mean flow properties, the parameters needed to implement the scheme are thermal heat capacity of the soil, surface aerodynamic roughness, latitude, solar declination, surface albedo, surface emissivity and atmospheric transmissivity.Sample calculations are presented for (a), constant atmospheric forcing at the reference level, and (b) variable atmospheric forcing corresponding to Kahle's (1977) measurements of windspeed, air temperature and radiometer soil surface temperature under dry vegetatively sparse conditions in the Mohave Desert in California. The latter case simulated the observed diurnal variations resonably well for the parameters used.Consultant, Atmospheric Sciences Division, Department of Energy and Environment, Brookhaven National Laboratory, Upton, N.Y., pc11973, U.S.A.  相似文献