共查询到20条相似文献，搜索用时 156 毫秒
1.
Patrick Cassen Ray T. Reynolds Frank Graziani Audrey Summers John McNellis Linda Blalock 《Physics of the Earth and Planetary Interiors》1979,19(2):183-196
The effect of solid convection on the thermal evolution of the Moon is explored for a variety of viscosities, radioactive differentiation efficiencies and initial temperature profiles. Convective heat flux in the models is calculated using an empirical relation derived from the results of laboratory experiments and numerical solutions of the Navier-Stokes equations. The method retains the spherically symmetric approximation and, therefore, greatly facilitates numerical calculations.Results show that even though solid convection may determine the thermal state of the lunar interior, it does not necessarily produce a quasi-steady thermal balance between heat sources and surface loss. An imbalance persists, due to the cooling and growth of the nonconvecting lithosphere. The state of the lithosphere is sensitive to the efficiency of heat source redistribution, while that of the convecting interior depends primarily on rheology. Convecting models have viscosities of 1021–1022 cm2s?1 in their interiors; the central temperature must be above 1100°C. Convection occurring within the first billion years after formation could have led to mare flooding by magma produced in hot zones of convection cells. However, it cannot be shown from model calculations alone that solid convection must have dominated lunar thermal history. 相似文献
2.
Summary For the discussion of the physico-chemical state and the phase transitions in the earth interior it is necessary to compare the results of geophysical field measurements with geophysical solid state investigations in the laboratory under extremep,T-conditions. In correspondence with the theoretical studies about the behaviour of the materials in the deep earth we investigated two groups of materials: (I) different types of rocks with reference to their elastic and thermal behaviour under extreme conditions, (II) simple compounds of elements which belong possibly to the representatives of the deep mantle and the earth interior. The method for measurement of the thermal diffusivity and the influence of anisotropy on the propagation of elastic waves in different rocks is described. The results of the dependence of the electric resistivity on pressure and temperature on synthetic and natural chalkogenides of the 3d-transition metals are discussed.Publication No. 474 of the Central Earth Physics Institute, Academy of Sciences, 15 Potsdam, Telegrafenberg, GDR. 相似文献
3.
D. G. Taimazov 《Seismic Instruments》2009,45(1):78-82
A functional chart and a theory of the wire extensometer that compensates for wire creep, as well as baric and thermal effects, are described. In combination with the interior geodetic datum, the device is shown to be suitable for intermediate base (up to several hundred meters) observations of deformations in the Earth’s crust in superficial trenches; furthermore, it allows for a significant decrease in the mounting and operating costs as a result of implementing a network of areal deformation observations. 相似文献
4.
金星表层年龄和构造活动特点表明其岩石层在最近的地质历史时期经历过广泛的更新.这种全球性的表层改造与其内部热演化历史进程密切相关.如果金星存在相变形成的上、下地幔,依据现今所了解的金星物理性质和参量化的热对流理论,并且考虑金星地幔相变边界层状态对对流的控制作用,我们计算了金星热演化历史.结果表明,金星的热演化历史是一种非单调的冷却过程,在这种非单调的热演化历史进程中,金星地幔会出现大体等周期的翻转.由于参数选取的不同,翻转时金星上、下地幔的温差随时间可能出现稳定变化、逐渐加强、逐渐减弱三种不同演化模式,目前尚不能确定实际金星热演化历史究竟是哪一种模式.金星地幔相变边界层的穿透对流可能是推动其表层岩石层全球性更新的关键,导致其表层火山活动和地表构造以大致500 Ma时间间隔更新和重造. 相似文献
5.
Paul H. LeBlond 《地球物理与天体物理流体动力学》2013,107(3-4):371-376
Abstract It is shown, through calculation and physical arguments, that in a smoothly stratified fluid thermal diffusion plays a damping role comparable to that of viscosity only in the interior of the fluid, and not in the boundary layers. 相似文献
6.
Thermal histories of chondrite parent bodies are calculated from an initial state with material in a powder-like form, taking into account the effect of consolidation state on thermal conductivity. The very low thermal conductivity of the starting materials makes it possible for a small body with a radius of less than 100 km to be heated by several hundred degrees even if long-lived radioactive elements in chondritic abundances are the only source of heat. The maximum temperature is determined primarily by the temperature at which sintering of the constituent materials occurs. The thermal state of the interior of a chondrite parent body after sintering has begun is nearly isothermal. Near the surface, however, where the material is unconsolidated and the thermal conductivity is much lower, the thermal gradient is quite large. This result contradicts the conventional “onion-shell” model of chondrite parent bodies. But because the internal temperature is almost constant through the whole body, it supports a “multiple-parent bodies” model, according to which each petrologic type of chondrite comes from a different parent body. 相似文献
7.
Amir Khan 《Surveys in Geophysics》2016,37(1):149-189
Determining Earth’s structure is a fundamental goal of Earth science, and geophysical methods play a prominent role in investigating Earth’s interior. Geochemical, cosmochemical, and petrological analyses of terrestrial samples and meteoritic material provide equally important insights. Complementary information comes from high-pressure mineral physics and chemistry, i.e., use of sophisticated experimental techniques and numerical methods that are capable of attaining or simulating physical properties at very high pressures and temperatures, thereby allowing recovered samples from Earth’s crust and mantle to be analyzed in the laboratory or simulated computationally at the conditions that prevail in Earth’s mantle and core. This is particularly important given that the vast bulk of Earth’s interior is geochemically unsampled. This paper describes a quantitative approach that combines data and results from mineral physics, petrological analyses of mantle minerals, and geophysical inverse calculations, in order to map geophysical data directly for mantle composition (major element chemistry and water content) and thermal state. We illustrate the methodology by inverting a set of long-period electromagnetic response functions beneath six geomagnetic stations that cover a range of geological settings for major element chemistry, water content, and thermal state of the mantle. The results indicate that interior structure and constitution of the mantle can be well-retrieved given a specific set of measurements describing (1) the conductivity of mantle minerals, (2) the partitioning behavior of water between major upper mantle and transition-zone minerals, and (3) the ability of nominally anhydrous minerals to store water in their crystal structures. Specifically, upper mantle water contents determined here bracket the ranges obtained from analyses of natural samples, whereas transition-zone water concentration is an order-of-magnitude greater than that of the upper mantle and appears to vary laterally underneath the investigated locations. 相似文献
8.
Dr. Heinz Lettau 《Pure and Applied Geophysics》1951,19(1-2):1-18
Summary The analysis of surface temperature variations of the moon is based on the equations of heat conduction and heat continuity in the interior of the moon andStefan's law. During a well-defined process, as exemplified by a lunar eclipse, the local heat budget equation establishes a boundary condition at the moon surface which must be satisfied by solutions of the thermal diffusion equation in the interior. Three simplified models of the general case are discussed. They are characterized by special assumptions regarding the depth and time dependency of the thermic qualities of the material underlying the moon's surface. In short, the thermal diffusivity is assumed to be constant in the first model, a linear depth function in the second and a time function in the third. A unique solution can be obtained for model No. I such that the absolute surface temperature is approximately inversely proportional to the 6th root of time during the phase of total eclipse.Epstein's conclusion that the average surface of the moon might consist of highly porous rocks or fine dust is confirmed by the order of magnitude of the heat conductivity which produces the best fit between the theoretical curves and a plot ofPettit's observational data during the lunar eclipse of 1939. Existing differences between the observed and theoretical curves during the totality phase of the eclipse can be reduced by the employment of the second model. A crude estimate shows that the average dust cover resting on more solid ground of lunar rocks might possibly have a thickness of approximately 0.5 meters. 相似文献
9.
Calculations of thermal effects of oxidation-reduction reactions in the open systems for the undifferentiated earth have been carried out up to 2000 kbar. It is shown that a change in the sign of the thermal effect occurs with increase of pressure in these open systems: endothermal reactions which occur at pressures Ps < Pc become exothermal at pressures Ps > Pc and vice versa. At a certain critical pressure Ps = Pc the enthalpy of reaction is equal to zero.The results of calculations show that the central part of the earth and the deep interior could become warm due to reduction processes (for example reduction of ferromagnesian silicates and oxides, and stishovite) during core formation. Reducing conditions in the undifferentiated earth during core formation imply that a large fraction of the total heat of chemical reactions was released in the deep interior and was absorbed in the upper parts of the planet. 相似文献
10.
地球内部物质组成的研究涉及对地表现象的深入解释,与地球动力学、地球热结构及宇宙演化有着密切的关系.本文综述了这方面的研究结果及近期的进展,指出两种地幔模型的主要分歧点,讨论了地幔中的主要相变及与间断面的关系,对今后研究提出四点意见. 相似文献
11.
12.
Thermal history of Mimas and Enceladus is investigated from the beginning of accretion to 400 Myr. The numerical model of convection combined with the parameterized theory is used. The following heat sources are included: short lived and long lived radioactive isotopes, accretion, serpentinization, and phase changes. The heat transfer processes are: conduction, solid state convection, and liquid state convection. We find that temperature of Mimas’ interior was significantly lower than that of Enceladus. If Mimas accreted 1.8 Myr after CAI then the internal melting and differentiation did not occur at all. Comparison of thermal models of Mimas and Enceladus indicates that conditions favorable for the start of tidal heating lasted for a short time (~107 yr) in Mimas and for ~108 yr in Enceladus. This could explain the Mimas—Enceladus paradox. In fact, in view of the chronology based on cometary impact rate, one cannot discard a possibility that also Mimas was for some time active and it has the interior differentiated on porous core and icy mantle. 相似文献
13.
The effects of variable viscosity on flow dynamics within spherical shells are investigated using a finite-element thermal convection model, and preliminary result for cases with relatively low Rayleigh numbers and small viscosity contrasts are reported. These results demonstrate some general effects of viscosity variation on mantle dynamics, and, in particular, the generation of toroidal energy. Since lateral viscosity variations are necessary in the generation of toroidal motion in a thermally driven convective system, it is not surprising our results show that flows with greater viscosity contrasts produce greater amounts of toroidal energy. Our preliminary study further shows that solutions become more time-dependent as viscosity contrasts increase. Increasing the Rayleigh number is also found to increase the magnitude of toroidal energy. Internal heating, on the other hand, appears to lead to less toroidal energy compared wth bottom heating because it tends to produce a thermally more uniform interior and thus smaller viscosity variations. 相似文献
14.
Yu. V. Frolova S. N. Rychagov V. M. Ladygin M. V. Luchko M. S. Chernov I. A. Boikova 《Journal of Volcanology and Seismology》2016,10(3):170-187
This study is concerned with structural and mineralogic transformations and changes in the physical and mechanical properties of volcanogenic sedimentary rocks in the North Paramushir hydrothermal magmatic system as a result of the interaction with thermal waters of various compositions and origins. We identified the following hydrothermal metasomatic facies that developed in tuffites and tuffs: opalites (monoopalite, opal–clay, and opal–alunite), as well as low- and moderate-temperature propylites. We show the position of each new facies in the structure of the hydrothermal magmatic system. We obtained correlative relationships of the physical and mechanical properties of the rock to the intensity and character of secondary alteration. It is pointed out that all of these rocks obey a common trend in the interrelationships between their properties, which may provide evidence of a common origin and progressive direction of hydrothermal processes in the interior of the North Paramushir system. 相似文献
15.
The regularly spaced surface structure observed on ropy pahoehoe basalt flows may be interpreted as folds which develop at the surface of a fluid whose viscosity decreases with depth. Folds form by the selective amplification of an irregular waviness in surface shape during shortening of the flow surface. The development of a regular fold arc length, predicted by folding theory, is reflected in the length scale of pahoehoe ropes. Pahoehoe fold arc lengths and the strength of the folding instability are determined by: (1) the ratio of the surface viscosity to the interior viscosity; (2) the thickness of the thermal boundary layer across which the viscosity changes; and (3) the ratio of the surface compressive stress to a stress related to the weight of the lava.The braided appearance of many ropy pahoehoe flows can be explained by a superposition of two episodes of folding. 相似文献
16.
渤海湾盆地冀中坳陷是我国最典型的潜山油气藏富集区.本文借助117口钻井地层测温资料和45块实测岩石热导率数据系统研究了冀中坳陷现今地温梯度、大地热流、热岩石圈厚度、岩石圈热结构等地热特征参数.研究表明,冀中坳陷0~3000m统一深度现今地温梯度为20.8~41.0℃·km-1,平均值为31.6℃·km-1,比未校正值减小1~3℃·km-1;现今大地热流介于48.7~79.7mW·m-2,平均值为59.2mW·m-2.平面上,冀中坳陷现今地温梯度和热流由西向东(从盆地边缘向内部)逐渐增大,并且凸起区地温梯度和热流相对较高,而凹陷区则偏低,与基底地形起伏具有很好的对应关系.同时,冀中坳陷腹部高热流凸起区广泛分布地热田.冀中坳陷现今热岩石圈厚度为98~109km,其岩石圈热结构为一典型的"冷壳热幔"型.本研究不仅对冀中坳陷油气勘探与地热能开发具有重要的指导意义,而且为深部岩石圈研究(华北克拉通破坏科学问题)提供了新依据. 相似文献
17.
Magellan radar images of the surface of Venus show a spatially broad distribution of volcanic features. Models of magmatic ascent processes to planetary surfaces indicate that the thermal structure of the interior significantly influences the rate of magmatic cooling and thus the amount of magma that can be transported to the surface before solidification. In order to understand which aspects of planetary thermal structure have the greatest influence on the cooling of buoyantly ascending magma, we have constructed magma cooling profiles for a plutonic ascent mechanism, and evaluated the profiles for variations in the surface and mantle temperature, surface temperature gradient, and thermal gradient curvature. Results show that, for a wide variety of thermal conditions, smaller and slower magma bodies are capable of reaching the surface on Venus compared to Earth, primarily due to the higher surface temperature of Venus. Little to no effect on the cooling and transport of magma are found to result from elevated mantle temperatures, elevation-dependent surface temperature variations, or details of the thermal gradient curvature. The enhanced tendency of magma to reach the surface on Venus may provide at least a partial explanation for the extensive spatial distribution of observed volcanism on the surface. 相似文献
18.
Morton C. Smith 《Pure and Applied Geophysics》1978,117(1-2):290-296
Natural heat stored in the earth's interior represents an essentially inexhaustible energy supply which, at usefully high temperatures, is accessible at practical drilling depths from almost anywhere on the earth's land surface. The problems of extracting and using this heat are those of engineering and economics, and can be expected to vary with the local geology and value of thermal energy. The first major experimental system designed to investigate these problems in one common type of geologic environment has recently been completed in the crystalline rock underlying the Jemez Plateau of northern New Mexico. It consists principally of two boreholes connected at a depth of about 2.7 km by a system of hydraulic fractures produced in granitic rock at a temperature of approximately 185°C. Cool water injected through one hole is heated as it flows through the fractures, and is recovered through the second hole as pressurized, superheated water. In a surface heat-exchange system now being completed, this heat will be extracted and the cool water reinjected to maintain a continuous, closed, pressurized-water energy-extraction loop. 相似文献
19.
Geotemperature and heat flow patterns in a large-scale Meso-Cenozoic basin such as the North China Basin are strongly affected by the relief of the basement, and controlled by the contrast of thermal conductivity between basement rock and sedimentary cover. Usually, heat flow observed at the surface of a basement uplift is greater than that of a basement depression. Calculation revealed, that the ratio of the former and the latter is determined by the uplifted height (H) of the bed-rock roof of the basement and the thickness (h) of the sedimentary cover. The relief of the basement also disturbs the geotemperature and, hence, the heat flow patterns at shallow depth. Consequently, the more or less “uniform” one dimensional heat flow from the deep interior of the Earth becomes two dimensional at shallow depth with great lateral and vertical variations. The extent of the disturbed zone is also controlled by the contrast of the thermal conductivity between basement rock and sedimentary cover as well as the uplifted heigh (H) of the bed-rock roof of the basement. Numerical computation demonstrated that the disturbed depth (Ze) is usually about 3–6 times of the uplifted height (H) of a basement uplift. 相似文献
20.
把地球表面潮汐形变问题扩展到地球内部.定义了Love函数和几种潮汐形变因子,并对两个实际地球模型（1066A和PREM）进行数值计算和讨论,以了解地球内部的潮汐形变特征,专门讨论了Love函数导数以及应力固体潮张量的计算问题.本工作对了解全地球潮汐场以及潮汐触发地震等问题将有所帮助. 相似文献