摘要:

The interpretation of heat flow anomalies in terms of contrasts of heat sources was treated in part 1; the effect on surface heat flow of the initial temperature of intrusive bodies is treated here. From the solution for an instantaneous point source, expressions are obtained for a finite line source, strip source, rectangular parallelepiped, sill edge, horizontal rectangular cylinder, dipping dike, and a buried sphere. Solutions for two‐ and three‐dimensional bodies of arbitrary shape are derived in a form suitable for digital computation. The heat flow at the surface of the earth is obtained for each c

ISSN:8755-1209    

DOI:10.1029/RG005i002p00109

年代:1967

数据来源: WILEY

摘要:

Numerical models for igneous activity on any planet must be based on thermal properties and melting relationships for realistic multicomponent systems. A consistent model for the composition of the earth's mantle may be obtained by considering a mixture of basalt and dunite, as postulated by Ringwood and others, if the uranium, thorium, and potassium concentrations of the basalt are similar to that of basalts dredged from the deep ocean floors. Present evidence does not indicate that the bulk composition of the moon is appreciably different from that of the earth's mantle.On the basis of a review of existing phase equilibria and high pressure studies, we predict melting behavior as a function of pressure and temperature for a composition equivalent to 1 part basalt and 3 parts dunite. The specific heat and fusion properties of the important minerals in this system are reviewed. The implications of these data for an understanding of magma generation are discussed.A review of the factors influencing the thermal conductivity of rocks indicates that when considering the details of heat conduction under conditions likely to be encountered within the earth's upper mantle and the moon, a model invoking constant phonon conductivity and temperature independent photon mean free path may be unrealistic. A more likely, but still oversimplified, model has a phonon conductivity inversely proportional to temperature, and, unless scattering dominates, a photon mean free path directly proportional to temperature over the range of interest. Pressure should not significantly affect the thermal conductivity within the upper mantle, except by changing the stable mineral assemblage.When the more important aspects of the melting relationships and thermal properties of the model composition are selected and used to extend thermal history calculations of the moon to include the effects of differentiation through igneous activity, the calculations indicate that a brief period of intense volcanic activity is likely to have occurred at a time which is primarily a function of the moon's temperature at the time of its formation and the concentration of radioactive heat sources. If the temperature of the moon at the time of its formation were 0°C and the uranium content were 0.05 ppm, with Th/U and K/U in the ratio 3.7 and 104, respectively, melting would have begun about 1.5 × 109years after formation, the intensity being largely controlled by the thermal conductivity. At lower U, Th, and K contents, the onset of volcanism would have been delayed or suppressed completely, depending on the conductivity. Properly selected samples of the moon's surface rocks should thus make it possible to determine its initial temperature. The total thickness of extrusive and intrusive igneous rocks is shown to be critically dependent on the efficiency of radiative heat transfer in removing heat from the interio

ISSN:8755-1209    

DOI:10.1029/RG005i002p00121

年代:1967

数据来源: WILEY

摘要:

Recently, well‐substantiated reports of color changes and other evidence of lunar activity have led to increased interest in the possibility that the moon is not entirely inert. About 400 events, most in the 18th, 19th, and 20th centuries, are analyzed from the following points of view: (1) type of event; (2) relative frequency and duration; (3) lunar phase; (4) correlation with solar activity; (5) position in the lunar orbit around the earth; (6) positions on the face of the moon of the sites of the events. Evidence is presented suggesting that the onset of a lunar event may be associated with disturbance of the lunar crust. A correlation with lunar tides has been found; the distribution of sites over the lunar surface is consistent with a hypothesis of disturbance of the surface layers through internal causes. Physical conditions in the lunar surface layers are, however, unknown; therefore many uncertainties remai

ISSN:8755-1209    

DOI:10.1029/RG005i002p00173

年代:1967

数据来源: WILEY

摘要:

TheFregion and the magnetosphere are under regular observation by the incoherent‐backscatter radar technique at three stations near 70°W longitude and ranging in magnetic latitude from the equator (Jicamarca, Peru), through 30°N (Arecibo, Puerto Rico), to 55°N (Millstone Hill, Massachusetts), and three other stations: Prince Albert in Canada, Nancay in France, and Malvern in England.The total power backscattered from the electrons in a pulse volume at a particular height is related to the number of electrons in the volume when corrected for two factors, each of which usually does not exceed 2. The corrections provide for the lack of equilibrium in the electron and ion temperatures and for the ratio of the Debye shielding distance to the operating wavelength. The corrections can be deduced from a spectral analysis of the returned signal. Alternately, and particularly in theFregion, the electron density is determined by observing the differential Faraday rotation of the polarization of the signal, or, under certain conditions by measuring the weak spectral line at the electronic plasma frequency.The total scattered power can be considered to arise from two components: one component having a frequency spectrum spread around the transmitted frequency in a band corresponding to, and produced by, the electronic thermal motions, and the second component having a frequency spectrum spread around the transmitted frequency in a band corresponding to, and produced by, the ionic thermal motion. For all of the operating observatories, the conditions are such that the ionic component dominates in theFregion and lower magnetosphere, and, since ionic thermal motion depends not only on the ion temperature but also on the ion mass, it is possible to identify the dominant ion and the ionic composition where mixtures are present. The ionic thermal motion fixes the characteristic width of the spectrum, but the shape of the central region of the spectrum is largely due to the ratio of the electron to ion temperatures. Hence from spectra at various heights it is possible to deduce electron temperature, ion temperature, and ionic composition all as functions of height.The three stations near 70°W longitude have regular observational programs that have extended over a year or more. Although the results of these programs are not published for all stations, the principal results will be summarized.Electron density profiles show values of 0.5 × 104at 10,000 cm−3at 10,000 km (daytime, Jicamarca) and of 5 × 104and 1 × 104at 1000 km (daytime and night, Jicamarca). At all stations diurnal patterns are apparent in the height of the maximum of theF2layer, including rapid changes near sunrise. Ion production and loss rates are inferred for certain times and heights.The ion temperature during the day increases from about 1000 degrees near theFpeak to a few thousand degrees at about 800 kilometers and remains isothermal to the limits of the observation (usually less than 1500 km). At night the values are about one‐half these values. The electron temperature near theFpeak is higher than the ion temperature by a factor that may reach 3 in the daytime but is only slightly above 1 at night. At greater heights the electron and ion temperatures agree.The dominant ion in theFregion is O+, changing to H+at about 1000 km during the day and at about 700 km at night. He+is observed in the transition region but in amounts of 10% or 20% of the ion content. These observations are made during quiet solar conditions.Traveling ionospheric disturbances having a wave structure have been observed at heights ranging from 150 km to the limit of observation (about 800 km) and are associated with predictable magnetic storms. They are interpreted in terms of gravity waves on the interface of the cool lowerFregion and warmer magnetosphere.Photoelectrons produced in the sunlit hemisphere contribute a measurable amount of heat at the conjugate point before it

ISSN:8755-1209    

DOI:10.1029/RG005i002p00191

年代:1967

数据来源: WILEY