Planetary science: A lunar perspective: Stuart Ross Taylor. Lunar and planetary Institute,Houston, 1982. xix + 481 pp., $39.95     

William M. Kaula 《Icarus》1982,51(3):670-671

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Sedimentology of the Middle Marker (3.4 Ga), Onverwacht Group,Transvaal, South Africa     

William P. Lanier  Donald R. Lowe 《Precambrian Research》1982,18(3):237-260

The Middle Marker is a thin (3–6 m) sedimentary unit at the base of the Hooggenoeg Formation in the 3.4 Ga old Onverwacht Group, Barberton Mountain Land, South Africa. The original sediments consisted largely of current-deposited volcaniclastic detritus now represented by green to buff-colored silicified volcaniclastic rock and fine-grained gray chert. Black chert, possibly formed by the silicification of a non-volcaniclastic precursor, makes up a significant part of the unit. The Middle Marker is underlain and overlain by mafic and commonly pillowed volcanic flowrock. Although the original sediment has been replaced by and/or recrystallized to a microquartz, chlorite, sericite, carbonate and iron oxide mosaic under lower greenschist-grade metamorphism, sedimentary textures and structures are remarkably well preserved. Textural pseudomorphs indicate the primary volcaniclastic sediment consisted of a mixture of crystal, vitric and lithic debris. Middle Marker sediments were deposited as a prograding, cone-flanking volcaniclastic sedimentary platform in a relatively-shallow and locally current/wave-influenced subaqueous sedimentary environment. Available paleocurrent data indicate a largely bimodal, orthogonal distribution pattern which is quite similar to both ancient and modern shallow marine/shelf systems. Diagnostic evidence for tidal activity is lacking. As felsic volcanic activity waned, an extensive airfall blanket of fine-grained volcanic ash and dust was deposited in a low-energy subaqueous environment. The sedimentary cycle was terminated with a renewal of submarine mafic volcanism. Middle Marker volcaniclastic sediments accumulated in an anorogenic basin removed or isolated from the influence of continental igneous and metamorphic terranes. Although compositionally dominated by a volcanic source, Middle Marker sediments owe their final texture and sedimentary structures to subaqueous sedimentary rather than volcanogenic processes.  相似文献   

Lightning generation in planetary atmospheres     

Zev Levin  William J. Borucki  Owen B. Toon 《Icarus》1983,56(1):80-115

The possibilities of lightning generation on other planets are considered, and the basic conditions that exist in terrestrial clouds during lightning discharges and the various theories of charge separation are reviewed. Recent measurements of cloud structure and whistlers, as well as optical observation of lightning on Jupiter, suggest that charge separation and lightning discharges occur on other planets in ways similar to those in which they occur on Earth. Using these terrestrial ideas, it is concluded that lightning on Venus will probably be found in clouds that are located in regions of convection such as those observed downwind of the subsolar point. It is also possible that if volcanoes on Venus are erupting, they too can produce lightning discharges in their plumes although it seems unlikely that this process can account for the observed rate of discharge. Jovian lightning is most probably generated in the lower water-ice clouds. These clouds are of moderate temperatures and have strong convection and large mass loading, all important ingredients for electrical buildup. Lightning is all but ruled out for Mars, even though some electrification is possible owing to the large dust storms on that planet.  相似文献   

Theoretical interpretation of the ground-based photometry of Saturn's B ring     

Kari Lumme  William M. Irvine  Larry W. Esposito 《Icarus》1983,53(2):174-184

New photographic photometry at small tilt angles during the 1979 and 1981 apparitions is combined with earlier data to yield several physical parameters for Saturn's B ring in red and blue colors. Phase curves are obtained for a mean tilt angle B ? 6°. The value of the volume density D is 0.020±0.004 with no indication of dependence on either the color or the tilt angle for 6°<B<26°. This conclusion is not altered significantly if the individual ring particles have a phase function similar to the phase curves of bright solar system objects. For the geometric albedo of a single particle we derive 0.61±0.04 (red) and 0.41±0.03 (blue), which are superior to earlier estimates because of the additional data now available. These values and the derived amount of multiple scattering as a function of tilt angle constrain the particle phase function in the red to be moderately backscattering. Inferred values of the particle single-scattering albedo are $\text{0.7≤}\text{ω}{}_0\text{(}\text{red}\text{) ≤0.92}$ and $\text{0.5≤}\text{ω}{}_0\text{(}\text{blue}\text{) ≤0.7}$, depending on the choice of phase function. No indication was found that the particle photometric properties might depend on the vertical distance from the central plane. Our results show that the ground-based photometry is entirely consistent with the classical, many-particle-thick ring model.  相似文献   

The comparative study of the planets: Angioletta Coradini and Marcello Fulchignoni,Editors. D. Reidel Publ. Co., Dordrecht, 1982. 516 pp., f140     

William K. Hartmann 《Icarus》1983,53(3):552

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A general precompiler for algebraic manipulation     

Randall L. Ricklefs  William H. Jefferys  Roger A. Broucke 《Celestial Mechanics and Dynamical Astronomy》1983,29(2):179-190

A generalized precompiler for systems performing algebraic manipulation of Poisson series has been written. It accepts a trigonometric superset of FORTRAN IV similar to Jefferys' TRIGRUN language (Jefferys, 1972) and generates a valid FORTRAN IV program which drives an abstract formula manipulation machine. This machine is designed to be generally compatible with any manipulation system, and has been implemented with two such systems. The precompiler is written in standard FORTRAN IV and was designed to allow simple conversion for use on most computers.  相似文献   

On the temperature dependence of the reaction O + NO → NO¹₂     

William E. Sharp 《Planetary and Space Science》1984,32(2):257-260

The published data on the temperature dependence of the radiative combination of atomic oxygen with nitric oxide at pressures near 1 torr is examined. Arguments are advanced to suggest that radiation near the cut-off wavelength (～ 3875Å) is coming from the unstabilized activated complex, No¹₂. At 4000Å a positive activation energy of 1 kcal mole^?1 is deduced. Application of this temperature dependence with the rate coefficient at 5200Å is made to airglow measurements in aurora. The deduced NO concentration is about 10⁹ cm^?3, in general agreement with that deduced from the measured NO⁺/O⁺₂ ratio as well as an auroral model prediction.  相似文献   

Photometric analysis of EL Aqr     

Surjit S. Wadhwa  William J. Zealey 《Astrophysics and Space Science》2004,291(1):21-25

We present an analysis of the Hipparcos and ASAS photometry of the W UMa star EL Aqr. The Wilson-Devinney code is employed in conjunction with recent spectroscopic mass ratio of 0.203 to model the V band light curve. We confirm that the system is an A type contact binary however our analysis suggests that it is over massive for its spectral class and has a relatively high fillout of 44%. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Trends in atmospheric Cd deposition recorded in a 64-meter long ice-core and a 5-m snow pit record from Devon Island,Nunavut, Canada     

Zheng  Jiancheng  Krachler  Michael  Fisher  David  Shotyk  William 《中国地球化学学报》2006,25(1):15-15

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La Cordillera Central Colombiana transecto Parque Los Nevados. ECOANDES Volume 5. Studies on tropical Andean ecosystems. T. van der Hammen and Alice G. Santos (eds). Publisher Gebrüder Borntraeger,Berlin, 2003 (545 pp., 3 maps, 1 CD‐Rom). ISBN: 3 443 65004 X     

William D. Gosling  Dunia H. Urrego 《第四纪科学杂志》2006,21(1):107-108

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