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1.
In situ measurements of lunar surface brightness temperatures made as a part of the Apollo Lunar Surface Experiments Package at the Apollo 15 Hadley Rille landing site are reported. Data derived from 5 thermocouples of the Heat Flow Experiment, which are lying on or just above the surface, are used to examine the thermal properties of the upper 15 cm of the lunar regolith using eclipse and nighttime cool-down temperatures. Application of finite-difference techniques in modeling the lunar soil shows the thermocouple data are best fit by a model consisting of a low-density and low-thermal conductivity surface layer approximately 2 cm thick overlying a region increasing in conductivity and density with depth. Conductivities on the order of 1 × 10?5 W/cm-°K are postulated for the upper layer, with conductivity increasing to the order of 1 × 10?4 W/cm-°K at depths exceeding 20 cm. An increase in mean temperature with depth indicates that the ratio of radiative to conductive transfer at 350°K is 2.7 for at least the upper few centimeters of lunar soil; this value is nearly twice that measured for returned lunar fines. The thermal properties model deduced from Apollo 15 surface temperatures is consistent with earth-based microwave observations if electrical properties measured on returned lunar fines are assumed. 相似文献
2.
L.E. Nyquist J.L. Wooden C.-Y. Shih H. Wiesmann B.M. Bansal 《Earth and Planetary Science Letters》1981,55(3):335-355
We report Sr, Nd, and Sm isotopic studies of lunar basalt 12038, one of the so-called aluminous mare basalts. A precise internal Rb-Sr isochron yields a crystallization age of 3.35±0.09 AE and initial87Sr/86Sr=0.69922?2 (2σ error limits, 1AE=109 years, λ(87Rb)=0.0139AE?1). An internal Sm-Nd isochron yields an age of 3.28±0.23AE and initial143Nd/144Nd=0.50764?28. Present-day143Nd/144Nd is less than the “chondritic” value, i.e. ?(Nd, 0)=?2.3±0.4 where ?(Nd) is the deviation of143Nd/144Nd from chondritic evolution, expressed as parts in 104. At the time of crystallization ?(Nd, 3.2AE)=1.5±0.6.We have successfully modeled the evolution of the Sr and Nd isotopic compositions and the REE abundances within the framework of our earlier model for Apollo 12 olivine-pigeonite and ilmenite basalts. The isotopic and trace element features of 12038 can be modeled as produced by partial melting of a cumulate mantle source which crystallized from a lunar magma ocean with a chondrite-normalized REE pattern of constant negative slope. Chondrite-normalized La/Yb=2.2 for this hypothetical magma ocean pattern. A plot of I(Sr) versus ?(Nd) for the Apollo 12 basalts clearly shows the influence of varying proportions of olivine, clinopyroxene, orthopyroxene, and plagioclase in the basalt source regions. A small percentage of plagioclase (～5%) in the 12038 source apparently is responsible for low I(Sr) and ?(Nd) in this basalt. Aluminous mare basalts from Mare Crisium (Luna 24) and by inference Mare Fecunditatis (Luna 16) occupy locations on the I(Sr)-?(Nd) plot similar to that of 12038, implying that some basalts from three widely separated lunar regions came from plagioclase-bearing source regions. A summary of model calculations for mare basalts shows a record of lunar mantle solidification during the period when REE abundances in the lunar magma ocean increased from ～20× chondritic to >100× chondritic. Although there is a general trend from olivine to clinopyroxene-dominated source regions with progressive magma ocean evolution, significant mineralogical heterogeneities in mantle composition apparently formed at any given stage of evolution, as evidenced in particular by the three Apollo 12 magma types. 相似文献
3.
Radial thickness variation in impact crater ejecta: implications for lunar basin deposits 总被引：1，自引：0，他引：1
A review of cratering data and available semi-empirical calculations suggests that the variation of ejecta thickness,t, with increasing range from lunar craters may be approximately modelled by the expression: t=0.14R0.74(r/R?3.0 wherer is range from the center of the crater andR, the crater radius, all in meters. This equation has been used to estimate the thickness of ejecta deposits at each of the Apollo sites contributed from the large multi-ringed frontside lunar basins. Predicted average thickness of Imbrium ejecta at Apollo 15 is 812 m; at Apollo 14, 130 m; at Apollo 17, 102 m; and at Apollo 16, 50 m. Since the sequence of formation of these basins is known, the stratigraphic column resulting from superimposed ejecta blankets can be calculated. Results suggest that pre-Nubium crustal material at upland Apollo sites lies at depths greater than 280 (Apollo 14) to 1940 m (Apollo 17). Predicted stratigraphic sections for the Apollo sites are tabulated. 相似文献
4.
Reviewing 92 measurements of lunar sample dielectric constant versus density at frequencies above 100 kHz, gives the relationK′ = (1.93 ± 0.17)p by regression analysis, where K′ is the dielectric constant of a soil or solid at a density ofpg/cm3. This formula is the geometric mean between the dielectric constant of vacuum (1) and the zero porosity dielectric constant of lunar material. Similarly, the loss tangent (D) can be described byD = [(0.00053 ± 0.00056) + (0.00025 ± 0.00009)C]p whereD is the loss tangent at densitypg/cm3 withC percent of total FeO + TiO2 (approximately proportional to ilmenite content). Using the density versus depth relations derived from lunar surface core tubes, and from laboratory studies of lunar soil compression gives a model of the dielectric properties as a function of depth in the lunar regolith. The dielectric constant increases smoothly with depth, as a function of the soil compaction only. The loss tangent, however, is more sensitive to the ilmenite content than it is to density. Neither dielectric constant nor loss tangent varies significantly with the temperature observed in a lunar day. 相似文献
5.
FAMOUS basalt 527-1-1 (a high-Mg oceanic pillow basalt) has three generations of spinel which can be distinguished petrographically and chemically. The first generation (Group I) have reaction coronas and are high in Al2O3. The second generation (Group II) have no reaction coronas and are high in Cr2O3 and the third generation (Group III) are small, late-stage spinels with intermediate Al2O3 and Cr2O3. Experimental synthesis of spinels from fused rock powder of this basalt was carried out at temperatures of 1175–1270°C and oxygen fugacities of 10?5.5 to 10?10 atm at 1 atm pressure. Spinel is the liquidus phase at oxygen fugacities of 10?8.5 atm and higher but it does not crystallize at any temperature at oxygen fugacities less than 10?9.5. The composition of our spinels synthesized at 1230–1250°C and 10?9 atmfO2 are most similar to the high-Cr spinels (Group II) found in the rock. Spinels synthesized at 1200°C and 10?8.5 atmO2 are chemically similar to the Group III spinels in 527-1-1. We did not synthesize spinel at any temperature or oxygen fugacity that are similar to the high-Al (Group I) spinel found in 527-1-1. These results indicate that the high-Cr (Group II) spinel is the liquidus phase in 527-1-1 at low pressure and Group III spinel crystallize below the liquidus (～1200°C) after eruption of the basalt on the sea floor. The high-Al spinel (Group I) could have crystallized at high pressure or from a magma enriched in Al and perhaps Mg compared to 527-1-1. 相似文献
6.
Ultrasonic compressional wave velocity Vp and quality factor Qp have been measured in alkali basalt, olivine basalt and basic andesite melts in the frequency range of 3.4–22 MHz and in the temperature range of 1100–1400°C. Velocity and attenuation of the melts depend on frequency and temperature, showing that there are relaxation mechanisms in the melts. Complex moduli are calculated from the ultrasonic data. The results fit well a complex modulus of Arrhenius temperature dependence with log-normal Gaussian distribution in relaxation times of attenuation. The analysis yields average relaxation time, its activation energy, relaxed modulus, unrelaxed modulus and width of Gaussian distribution in relaxation times. Relaxed modulus is smaller (17.5 GPa) for basic andesite melt of high silica and high alumina contents than for the other two basalt melts (18.1–18.4 GPa). The most probable relaxation times decrease from ～ 3 × 10?10 s for basic andesite to ～ 10?11 s for alkali basalt at 1400°C. Activation energies of attenuation, ranging from 270 to 340 kJ mol?1 in the three melts, are highest in basic andesite. Longitudinal viscosity values and their temperature dependences are also calculated from Vp and Qp data. The volume viscosity values are estimated from the data using the shear viscosity values. Longitudinal, volume and shear viscosities and their activation energies are highest in the basic andesite melt of the most polymerized structure. 相似文献
7.
The reaction of CO + OH? in aqueous solution to give formate was studied as a carbon monoxide sink on the primitive earth and in the present ocean. The reaction is first order in OH? and first order in the molar CO concentration. The second order rate constant is given by log k(M?1hr?1) = 15.83?4886/T between 25°C and 60°C. Using the solubility of CO in sea water, and assuming a pH of 8 for a primitive ocean of the present size, the halflife of CO in the atmosphere is calculated to be 12 × 106 yr at 0°C and 5.5 × 104 yr at 25°C.Three other CO sinks would have been important in the primitive atmosphere: CO + H2 → H2CO driven by various energy sources, CO + OH → CO2 + H, and the Fischer-Tropsch reaction of CO + H2 → hydrocarbons, etc. It is concluded that the lifetime of a CO atmosphere would have been very short on the geological time scale although the relative importance of these four CO sinks is difficult to estimate.The CO + OH? reaction to give formate is a very minor CO sink on the earth at the present time. 相似文献
8.
The study of thermal expansion by a dilatometer technique on a few granitic rocks from the Peninsular shield and Himalayan regions of India confirms that the linear coefficient of thermal expansion (α) is a function of heating rate, crack porosity, thermal cycling, mineral composition and grain orientation. Permanent set in the samples occurs at the limiting temperature (Tp) and restricts the validity of the apparent thermal-expansion coefficient with rise in temperature. Values of α are determined for a heating rate of ?2°C min?1 in order to calculate the volume coefficient of expansion (αv) and the temperature dependence of density (ρT). 相似文献
9.
Spectra of internal friction between 2 and 8 Hz were studied in a single crystal of enstatite, in a polycrystal of synthetic forsterite and in several samples of natural peridotite. Measurements of Q?1 and μ were performed in vacuum (10?6 torr), from room temperature up to 1100°C. For these experimental conditions no peak was observed in the polycrystalline undeformed forsterite, but the background attenuation irregularly increased from 5 · 10?3 to 10?2.A peak Q?1 = 7 · 10?2 appears in a deformed peridotite at 930°C. It is reduced of 60% after 5 h of annealing at 1100°C. But the background attenuation persists. In the single crystal of enstatite, a peak is observed at 760°C (Q?1 = 6 · 10?2). A mechanism involving dislocations is suggested as a possible explanation for the peak obtained with the peridotite samples. If this hypothesis is right, the observed effect would be diffusion controlled so that one can expect pressure to translate it towards higher temperature. This mechanism could therefore appear in the upper mantle. Background attenuation could be the result of intergranular thermal losses. 相似文献
10.
A summary of experiments and analyses concerning electromagnetic induction in the Moon and other extraterrestrial bodies is presented. Magnetic step-transient measurements made on the lunar dark side show the eddy current response to be the dominant induction mode of the Moon. Analysis of the poloidal field decay of the eddy currents has yielded a range of monotonic conductivity profiles for the lunar interior: the conductivity rises from 3·10?4 mho/m at a depth of 170 km to 10?2 mho/m at 1000 km depth. The static magnetization field induction has been measured and the whole-Moon relative magnetic permeability has been calculated to be . The remanent magnetic fields, measured at Apollo landing sites, range from 3 to 327 γ. Simultaneous magnetometer and solar wind spectrometer measurements show that the 38-γ remanent field at the Apollo 12 site is compressed to 54 γ by a solar wind pressure increase of 7·10?8 dyn/cm2. The solar wind confines the induced lunar poloidal field; the field is compressed to the surface on the lunar subsolar side and extends out into a cylindrical cavity on the lunar antisolar side. This solar wind confinement is modeled in the laboratory by a magnetic dipole enclosed in a superconducting lead cylinder; results show that the induced poloidal field geometry is modified in a manner similar to that measured on the Moon. Induction concepts developed for the Moon are extended to estimate the electromagnetic response of other bodies in the solar system. 相似文献
11.
R.P. Lin 《Physics of the Earth and Planetary Interiors》1979,20(2-4):271-280
Apollo 15 and 16 subsatellite measurements of lunar surface magnetic fields by the electron reflection method are summarized. Patches of strong surface fields ranging from less than ° to tens of degrees in size are found distributed over the lunar surface, but in general no obvious correlation is observed between field anomalies and surface geology. In lunar mare regions a positive statistical correlation is found between the surface field strength and the geologic age of the surface as determined from crater erosion studies. However, there is a lack of correlation of surface field with impact craters in the mare, implying that mare do not have a strong large-scale uniform magnetization as might be expected from an ancient lunar dynamo. This lack of correlation also indicates that mare impact processes do not generate strong magnetization coherent over ～ 10 km scale size. In the lunar highlands fields of >100 nT are found in a region of order 10 km wide and >300 km long centered on and paralleling the long linear rille, Rima Sirsalis. These fields imply that the rille has a strong magnetization (>5 × 10?6 gauss cm3 gm?1 associated with it, either in the form of intrusive, magnetized rock or as a gap in a uniformly magnetic layer of rock. However, a survey of seven lunar farside magnetic anomalies observed by the Apollo 16 subsatellite suggests a correlation with inner ejecta material from large impact basins. The implications of these results for the origin of lunar magnetism are discussed. 相似文献
12.
《Earth and Planetary Science Letters》2007,253(1-2):254-265
We report new high-precision laser fluorination three-isotope oxygen data for lunar materials. Terrestrial silicates with a range of δ18O values (− 0.5 to 22.9‰) were analyzed to independently determine the slope of the terrestrial fractionation line (TFL; λ = 0.5259 ± 0.0008; 95% confidence level). This new TFL determination allows direct comparison of lunar oxygen isotope systematics with those of Earth. Values of Δ17O for Apollo 12, 15, and 17 basalts and Luna 24 soil samples average 0.01‰ and are indistinguishable from the TFL. The δ18O values of high- and low-Ti lunar basalts are distinct. Average whole-rock δ18O values for low-Ti lunar basalts from the Apollo 12 (5.72 ± 0.06‰) and Apollo 15 landing sites (5.65 ± 0.12‰) are identical within error and are markedly higher than Apollo 17 high-Ti basalts (5.46 ± 0.11‰). Evolved low-Ti LaPaz mare-basalt meteorite δ18O values (5.67 ± 0.05‰) are in close agreement with more primitive low-Ti Apollo 12 and 15 mare basalts. Modeling of lunar mare-basalt source composition indicates that the high- and low-Ti mare-basalt mantle reservoirs were in oxygen isotope equilibrium and that variations in δ18O do not result from fractional crystallization. Instead, these differences are consistent with mineralogically heterogeneous mantle sources for mare basalts, and with lunar magma ocean differentiation models that result in a thick feldspathic crust, an olivine–pyroxene-rich mantle, and late-stage ilmenite-rich zones that were convectively mixed into deeper portions of the lunar mantle. Higher average δ18O (WR) values of low-Ti basalts compared to terrestrial mid ocean ridge basalts (Δ=0.18‰) suggest a possible oxygen isotopic difference between the terrestrial and lunar mantles. However, calculations of the δ18O of lunar mantle olivine in this study are only 0.05‰ higher than terrestrial mantle olivine. These observations may have important implications for understanding the formation of the Earth–Moon system. 相似文献
13.
Ki-iti Horai 《Physics of the Earth and Planetary Interiors》1981,27(1):60-71
The thermal conductivity of a simulated Apollo 12 lunar soil sample was measured with a needle probe under vacuum. The result showed that the sample, with bulk densities of 1.70–1.85 g cm?3 held in a vertical cylinder (2.54 cm in diameter and 6.99 cm long) has a thermal conductivity ranging from 8.8 to 10.9 mW m?1 K?1. This is comparable to the lunar regolith's thermal conductivity as determined in situ. Besides the dense packing of the soil particles, an enhanced intergranular thermal contact, due to the self-compression of the sample, is necessary to raise the sample's thermal conductivity from the level of loose soil (< 5 mW m?1 K?1) to that of the lunar regolith deeper than 35 cm (～ 10 mW m?1 K?1). A model of the lunar regolith, a thin layer of loose soil resting on a compacted self-compressed substratum, is consistent with the lunar regolith's surface structure as deduced from an observation of the lunar surface's brightness temperature. Martian regolith surface structure is similar, except that its surface layer may be missing in places because of aeolian activity. Measurements of thermal conductivity under simulated martian surface conditions showed that the thermal properties of loose and compacted soils agreed with the two peak values of the martian surface's thermal inertia as observed from “Viking” orbiters, suggesting that drifted loose soil and exposed compacted soil are responsible for the bimodal distribution of the martian surface's thermal inertia near zero elevation. For compacted soil exposed to the martian surface to have the same thermal conductivity as that buried under the surface layer, a cohesion of the soil particles must be assumed. 相似文献
14.
Relaxation experiments on vitreous SiO2, densified at 900°C, 20 kbar to a permanent density of 2.36 g cm?3 yield an activation energy of69 ± 5kcal mol?1 in the temperature range 700–800°C. The data can be used to estimate minimum cooling rates, maximum depositional temperatures or maximum thicknesses of shock-metamorphosed rocks containing diaplectic glasses, if relaxation of a glass densified under dynamic conditions is assumed to be similar to that of statically densified glass. 相似文献
15.
H. Berckhemer W. Kampfmann E. Aulbach H. Schmeling 《Physics of the Earth and Planetary Interiors》1982,29(1):30-41
An apparatus designed to determine the complex shear modulus of rock samples by forced torsion oscillations at high temperature and in the seismic frequency band 0.003–30 Hz is briefly described. Measurements were performed on natural dunite from Åheim (Norway) up to 1400°C and on polycrystalline forsterite up to 1500°C at 1 atm pressure. The two materials were chosen to study, by comparison, the effect of melt on the elasticity and anelasticity of mantle rocks.Between 1000 and 1200°C the absolute values of the shear modulus G are almost equal for both materials. Above 1200°C G for natural dunite decreases progressively with temperature and at 1400°C and 1 Hz reaches of its value at 1100°C. In contrast, G of pure forsterite depends little on temperature. For petrological reasons, supported by simultaneous measurements of the electric resistivity, there is strong evidence that the decrease of G in dunite above 1200°C is due to melt from the lower melting components of the dunite. Based on different models estimates of the melt fraction are made.At high temperature, in both materials Q?1 is characterized by a monotonic decrease with frequency according to ω?α, with α ≈ 0.25. An apparent activation energy of 38±5 kcal mol?1 for forsterite and 48±8 kcal mol?1 for dunite was found with no significant change in the regime of partial melting. From this it is concluded that Q?1, even at partial melting, is dominated by solid state high temperature background absorption. There is no indication from these experiments for a constant-Q-band at low seismic frequencies or an increase of Q proportional to frequency as suggested by some seismologists. The present results are in good qualitative agreement with those for Young's modulus obtained previously by strain retardation experiments. 相似文献
16.
V. M. Vitovtova V. M. Shmonov A. V. Zharikov 《Izvestiya Physics of the Solid Earth》2014,50(5):593-602
The depth trends of permeability are constructed from the measurements of the tight rocks typical of the basement of the continental crust at temperatures up to 600°C and pressures up to 200 MPa. It is established that the permeability decreases with depth. The statistical processing of the experimental data yielded the generalized dependence logk = ?12.6-3.23H 0.223. The method is suggested and, based on the experimental data on permeability, the estimates are obtained for the effective diameters of the pore channels and effective porosity at the PT parameters corresponding to the in situ deep zones of the continental crust. It is found that porosity decreases with depth, while distinct depth dependence of the pore sizes is not observed. The dependence of porosity on the depth is approximated by the relationship logφ = ?0.65–0.1H + 0.0019H 2. The porosity is estimated at a few percent for a depth of 10 km with a decline to 0.01–0.1% at 35 km. The estimates of porosity retrieved from the experimental data agree with the theoretical calculations based on the present-day ideas of the structure of the discrete media and with the results of magnetotelluric sounding. Thus, according to three independent estimates, the porosity of the rocks of the continental crust decreases with depth. At the same time, in both the intermediate and lower crust there are intervals where the porosity values suggest the presence of fluid-saturated horizons at these depths. 相似文献
17.
Data in the literature and additional measurements on the thermal diffusivities of granites, granulites and ultrabasic rocks at temperatures up to 1000 K and pressures to 2 GPa, have been used to propose a new model for thermal diffusivity distribution in the crust and upper mantle.The laboratory measurements were made using a pulse method or the Angstroem method with cylindrical heat flow. After making particular assumptions about the pressure and temperature distribution within the top 60 km the pressure and temperature dependencies of diffusivity were transformed into a depth dependence.The model is characterised by a continuous decrease of diffusivity to a depth of ～30 km where there is a small but rapid increase to a nearly constant value of 7.3 × 10?3 cm2 s?1. 相似文献
18.
The assumption of local equilibrium during partial melting is fundamental to the interpretation of isotope and trace element data for mantle-derived rocks. If disequilibrium melting is significant, the scale of the chemical and isotopic heterogeneity in the mantle indicated by the data could be as small as the grain size of the mantle rock, and the isotope data themselves are then of doubtful value to the understanding of mantle processes. To assess the scale of isotopic heterogeneity in a partially molten asthenosphere we review the Sr isotopic data of volcanic rocks from oceanic regions and the available experimental data on diffusion kinetics in minerals and melts similar to those existing in the mantle. Although diffusion data are scarce and afflicted with uncertainties, most of the diffusion coefficients for cations in mantle minerals at temperatures of 1000–1200°C appear to be greater than 10?13 cm2 s?1. Sr diffusion in liquid basalt is more rapid, with diffusion coefficients of D = 10?7 to 10?6cm2s?1 near 1300°C. Simple model calculations show that, with these D values, a fluid-free mantle can maintain a state of disequilibrium on a centimeter scale for periods of 108 to 109 years. The state of disequilibrium found in many mantle-derived xenoliths is thus easily explained. A partially molten mantle, on the other hand, will tend to equilibrate locally in less than 105 to 106 years. The analytical data on natural rocks likewise indicate that the inhomogeneities are both old (>FX1.5 b.y.) and regional in character and that the consistent isotopic difference between ocean island and ocean floor volcanics cannot be explained by small-scale heterogeneity of the source rock. 相似文献
19.
The matrix of 77135 would not be a liquid at less than 1280°C, 1 atm pressure. The petrography and lack of evidence of crystallization in the 1280-1150°C interval suggest that the matrix is either a devitrified, shock-melted and supercooled glass, or a devitrified, depressurised liquid whose liquidus temperature had been depressed by the presence of a small amount of water at pressures attainable in the upper part of the lunar crust. Devitrification fronts would have advanced faster than 1 mm min?1 in 77135 glass at 1050°C under lunar surface conditions. 相似文献
20.
Aviva Brecher 《Earth and Planetary Science Letters》1976,29(1):131-145
In reexamining the accumulated magnetic data on lunar rocks, several common patterns of magnetic behavior are recognized. Their joint occurrence strongly suggests a new model of lunar rock magnetism, which appeals only to partial preferred textural alignment of the spontaneous moments of magnetic grains, without requiring the existence of ancient lunar magnetic fields. This magnetic fabric, mimetic to locally oriented petrofabric, gives rise to an apparent “textural remanent magnetization” (TXRM). In order to account for the observed intensity of “stable remanence” in lunar rocks, only a minute fraction (10?3 to 10?5) of the single-domain iron grains present need be preferentially aligned. Several mechanisms operating on the lunar surface, including shock and diurnal thermal cycling, appear adequate for producing the required type and degree of magnetic alignment in all lunar rock classes. The model is supported by a wide variety of direct and indirect evidence and its predictions (e.g. regarding anisotropic susceptibility and remanence acquisition) can be experimentally tested. 相似文献