The horizontal component of spicule motion     

Spencer R. Weart 《Solar physics》1970,14(2):310-314

In movies of H spectra taken with the slit tangential to the solar limb we can observe motion of spicules both parallel to the slit and along the line of sight. We find strong evidence that, although most motion is along the axis of the spicule, some features move at right angles to their axes. Several cases were observed of features separating into two widely-split components. A power spectrum of the changes of Doppler shifts with time shows the 1/frequency characteristics of random motion.  相似文献   

Compact steep-spectrum sources from the S4 sample     

D. J. Saikia  S. Jeyakumar  C. J. Salter  P. Thomasson  R. E. Spencer  F. Mantovani 《Monthly notices of the Royal Astronomical Society》2001,321(1):37-43

We present the results of 5-GHz observations with the VLA A-array of a sample of candidate compact steep‐spectrum (CSS) sources selected from the S4 survey. We also estimate the symmetry parameters of high-luminosity CSS sources selected from different samples of radio sources, and compare these with the larger sources of similar luminosity to understand their evolution and the consistency of the CSS sources with the unified scheme for radio galaxies and quasars. The majority of CSS sources are likely to be young sources advancing outwards through a dense asymmetric environment. The radio properties of CSS sources are found to be consistent with the unified scheme, in which the axes of the quasars are observed close to the line of sight, while radio galaxies are observed close to the plane of the sky.  相似文献   

Variability of dense water formation in the Ross Sea   总被引：1，自引：0，他引：1  

Karen M. Assmann  Ralph Timmermann 《Ocean Dynamics》2005,55(2):68-87

This paper presents results from a model study of the interannual variability of high salinity shelf water (HSSW) properties in the Ross Sea. Salinity and potential temperature of HSSW formed in the western Ross Sea show oscillatory behaviour at periods of 5–6 and 9 years superimposed on long-term fluctuations. While the shorter oscillations are induced by wind variability, variability on the scale of decades appears to be related to air temperature fluctuations. At least part of the strong decrease of HSSW salinities deduced from observations for the period 1963–2000 is shown to be an aliasing artefact due to an undersampling of the periodic signal. While sea ice formation is responsible for the yearly salinity increase that triggers the formation of HSSW, interannual variability of net freezing rates hardly affects changes in the properties of the resulting water mass. Instead, results from model experiments indicate that the interannual variability of dense water characteristics is predominantly controlled by variations in the shelf inflow through a sub-surface salinity and a deep temperature signal. The origin of the variability of inflow characteristics to the Ross Sea continental shelf can be traced into the Amundsen and Bellingshausen Seas. The temperature anomalies are induced at the continental shelf break in the western Bellingshausen Sea by fluctuations of the meridional transport of circumpolar deep water with the eastern cell of the Ross Gyre. In the Amundsen Sea, upwelling due to a persistently cyclonic wind field carries the signal into the surface mixed layer, leading to fluctuations of the vertical heat flux, anomalies of brine release near the sea ice edge, and consequently to a sub-surface salinity anomaly. With the westward flowing coastal current, both the sub-surface salinity and deep temperature signals are advected onto the Ross Sea continental shelf. Convection carries the signal of salinity variability into the deep ocean, where it interacts with modified circumpolar deep water upwelled onto the continental shelf as the second source water mass of HSSW. Sea ice formation on the Ross Sea continental shelf thus drives the vertical propagation of the signal rather than determining the signal itself.  相似文献   

Near-surface models in Saudi Arabia     

Ralph Bridle  Robert Ley  Ameerah Al-Mustafa 《Geophysical Prospecting》2007,55(6):779-792

A single‐layer model of the near surface throughout the Kingdom of Saudi Arabia is available. While this simple model suffices for most areas and large subsurface structures, it fails in situations where the surface topography is complex, the base of weathering is below the datum, or where the time structural closure is less than the uncertainty in the static correction. In such cases, multiple‐layered models that incorporate velocities derived from analysis of first arrivals picked from seismic shot records have proved to be successful in defining the lateral heterogeneity of the near surface. The additional velocity information obtained from this first‐arrival analysis (direct as well as refracted arrivals) vastly improves the velocity–depth model of the near surface, regardless of the topography. Static corrections computed from these detailed near‐surface velocity models have significantly enhanced subsurface image focusing, thereby reducing the uncertainty in the closure of target structures. Other non‐seismic methods have been used either to confirm qualitatively or to enhance the layer models previously mentioned. Gravity data may be particularly useful in sandy areas to confirm general structure, while geostatistical modelling of vibrator base‐plate attributes has yielded information that enhances the velocity field. In the global context, exploration targets of the oil and gas industry are seeking smaller and lower relief‐time structures. Thus, near‐surface models will need to enhance and integrate these methods, particularly in areas where the assumption of flat‐lying near‐surface layers cannot be met.  相似文献   

Advanced techniques for clay mineral analysis: J.J. Fripiat (Editor). Elsevier,Amsterdam, 1982, vi + 234 pp., US $42.50/Dfl.100.00 (hardcover)     

Ralph E. Grim 《Sedimentary Geology》1983,34(4):341-342

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Hydrogeology of an Alkaline Fly Ash Landfill in Eastern Iowa   总被引：1，自引：0，他引：1  

Linda Le Seur Spencer  Lon D. Drake 《Ground water》1987,25(5):519-526

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Granites and yet more granites forty years on   总被引：17，自引：0，他引：17  

Wallace Spencer Pitcher 《International Journal of Earth Sciences》1987,76(1):51-79

The theme of this synoptic review is the relationship between cause, process, source and the geological context during the genesis of the granitic rocks. A close environmental relationship occurs because granites can arise as the end-stage of several generative processes, involving different source rocks, each appropriate to a particular tectonic situation. Expressed in geological terms the differences can be used to erect a genetic classification, to set in perspective the intervention of basic magma, to reveal the importance of the volcanoplutonic interface, to evaluate the significance of the texture, to predict the type of mineralisation, to understand the mode of emplacement and to determine the contribution of the various source rocks.

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Zusammenfassung Das Thema dieser synoptischen übersicht behandelt das Verhältnis zwischen Ursache, Prozess, Herkunft und dem geologischen Rahmen während der Genese granitischer Gesteine.Es besteht hier eine enge Beziehung, weil Granite das Endstadium sehr unterschiedlicher Entstehungsprozesse sein können, die verschiedene Ausgangsgesteine einbeziehen und von denen jeder einer speziellen tektonischen Situation entspricht.Geologisch ausgedrückt kann man die Unterschiede dazu verwenden, eine genetische Klassifikation zu erstellen, um damit den Einflu\ basischen Magmas im richtigen Verhältnis zu sehen, die Bedeutung des vulkanisch-plutonischen Grenzbereiches aufzuzeigen, die Wichtigkeit der Textur herauszustreichen und den Typ der Mineralisation vorherzusagen. Auf diese Weise lä\t sich das Verständnis für den Modus der Platznahme erzielen und der Einflu\ verschiedener Ausgangsgesteine abschätzen.

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Résumé Cette revue synoptique a pour thème les relations entre la cause, le processus, la source et le contexte géologique au cours de la genèse des roches granitiques. Il existe entre ces facteurs des relations étroites, car les granites peuvent représenter le stade final de plusieurs processus de genèse, impliquant des roches de départ diverses, et appropriés chacun à une situation tectonique particulière.Exprimées en termes géologiques, les différences peuvent Être utilisées en vue d'établir une classification génétique, de mettre en évidence l'intervention du magma basique, d'exprimer l'importance de l'interface volcano-plutonique, d'estimer la signification de la texture de mise en place et de déterminer la contribution des diverses roches de départ.

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On the solution of transient free-surface flow problems in porous media by the finite element method     

Ralph Ta-Shun Cheng  Chih-Yen Li 《Journal of Hydrology》1973,20(1):49-63

A numerical procedure is presented to deal with solution of transient free-surface flows in porous media. The governing boundary-value problem for the piezometric potential is solved by the finite element method. The initial-value problem which describes the transient motion of the free-surface is solved by the method of quasi-linearization. The numerical scheme has been applied to isotropic and anisotropic earth dam problem and also to a ditch drainage problem. Excellent agreements have been reached when compared with known solutions. This computational procedure is shown to be stable and suitable for this class of problems with the aid of a digital computer.  相似文献   

Minor and trace elements in some meteoritic minerals     

Ralph O. Allen  Brian Mason 《Geochimica et cosmochimica acta》1973,37(6):1435-1456

The mineral phases including olivine, orthopyroxene, clinopyroxene, troilite, nickel-iron, plagioclase, chromite and the phosphates were separated from several meteorites. These were a hypersthene chondrite (Modoc), a bronzite chondrite (Guareña), an enstatite chondrite (Khairpur), and two eucrites (Haraiya and Moore County); diopside was separated from the Nakhla achondrite. The purified minerals were analyzed for trace and minor elements by spark source mass spectrometry and instrumental neutron activation analysis. On the meteorites examined our results show that Co, Ni, Cu, Ge, As, Ru, Rh, Pd, Sn, Sb, W, Re, Os, Ir, Pt and Au are entirely or almost entirely siderophile; Na, Rb, Sr, Y, Ba and the rare earth elements lithophile; Se chalcophile. The transition elements So, Ti, V, Cr and Mn are lithophile in most stony meteorites, but show chalcophile affinities in the enstatite chondrites (and enstatite achondrites), as do Zn, Zr and Nb. In the ordinary chondrites Ga shows both lithophile and siderophile affinities, but becomes entirely siderophile in the enstatite chondrites. Molybdenum and tellurium show strong siderophile and weaker chalcophile affinity. The lithophile elements are distributed among the minerals according to the crystallochemical factors, the most effective controlling factor being ionic size.  相似文献   

Metamorphic petrology — mineralogical,field, and tectonic aspects | Francis J. Turner, 1981. 2nd ed. International Series in the Earth and Planetary Sciences. McGraw-Hill Book Co. GmbH,Hamburg, xv + 524 pp., DM 80.90 (hardcover)     

Ralph Kretz 《Earth》1982,18(1):98-99

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