ISSN:8755-1209    

DOI:10.1029/RG017i006p00000

年代:1979

数据来源: WILEY

摘要:

It is now more than a decade since geophysicists became generally aware of Wilson's (1965) recognition of the plate structure of the lithosphere. The implications of this recognition for the solid‐earth sciences have been so wide that a short review of achievements in the field can only be highly selective and must reflect strongly the prejudices of the reviewers—two field geologists. Major advances in plate tectonics since Dewey's review four years ago (Dewey, 1975a) have largely involved better understanding of the complexities of plate boundary phenomena although understanding of present plate motions continues to improve (Minster and Jordan, 1978). Revision of the basic principles of plate tectonics has not yet proved necessary, but intensive studies have revealed subtleties that may not have been clearly appreciated in the earliest resea

ISSN:8755-1209    

DOI:10.1029/RG017i006p01081

年代:1979

数据来源: WILEY

摘要:

The lithospheric plates of plate tectonics are created from hot mantle rock at ocean ridges and descend into the mantle at ocean trenches. The plates are by definition, part of mantle convection cells. A fluid heated from within or from below and cooled from above convects thermally if the Rayleigh number exceeds a critical value. The earth's mantle is heated from within due to the decay of radioactive isotopes and is heated from below by heat generation in the core.

ISSN:8755-1209    

DOI:10.1029/RG017i006p01090

年代:1979

数据来源: WILEY

摘要:

Continental collision, in the context of plate tectonics (Wilson 1966, 1968), is the aborted subduction of continental crust. Subduction gives way to horizontal compression because the low density of continental crust resists the gravitational re‐incorporation of the subducted lithosphere into the mantle (McKenzie 1969). Continued plate convergence leads to major fields of inhomogeneous strain within adjacent regions of the continental lithosphere. Depending on the composition of the upper plate of a subduction zone involved in collision, it is customary (Dewey and Bird 1970) to distinguish between arc‐continent (A‐C) collisions or, in part, obductions (Coleman 1970, Dewey 1976), arc‐arc (A‐A) collisions (Dewey, 1969), and continent‐continent (C‐

ISSN:8755-1209    

DOI:10.1029/RG017i006p01098

年代:1979

数据来源: WILEY

摘要:

During the last four years, major progress has been made in mapping regional variations in the strength of the lithosphere and in understanding the rheological properties of the upper mantle which are responsible for the plate‐like behavior of the lithosphere. It has long been recognized that the apparently rigid translations of the plates and the support of large topographic loads on the earth's surface require a strong lithosphere overlying a weak asthenosphere. Recently, interest in defining the detailed mechanical properties of the lithosphere has greatly increased, perhaps stimulated by the discovery of a double Benioff zone beneath Japan which may be related to the unbending of the subducted oceanic plate. Many investigators seem to be reaching a general consensus on a model of the oceanic lithosphere which is consistent with thermal models of the upper mantle, experimental rock mechanics, gravity and bathymetrie surveys, and patterns of seismicity and focal mechanism

ISSN:8755-1209    

DOI:10.1029/RG017i006p01109

年代:1979

数据来源: WILEY

摘要:

Viewed as a boundary value problem of continuum mechanics, the subject of earthquake mechanics reduces to the study of (1) constitutive properties (stress‐deformation laws) and geometry of fault zones and surroundings, and (2) remotely applied boundary conditions. In the purely quasi‐static formulations described here, a precise criterion for instability leading to dynamic rupture is also needed. The present consensus supports the concept of an earthquake cycle in which the somewhat arbitrarily chosen successive stages are (1) slow increase of stress due to remote loading, (2) the onset, propagation, and cessation of earthquake rupture, and (3) post‐seismic adjustment. Although no single rigorous model yet exists for the complete cycle because of simplifying constitutive assumptions, there are detailed models for each

ISSN:8755-1209    

DOI:10.1029/RG017i006p01115

年代:1979

数据来源: WILEY

摘要:

The term “brittle phenomena” includes a number of processes that are dominated by fracture as a mechanism or are controlled by the presence of preexisting fractures. Brittle phenomena in rocks are the most pervasive processes in the shallow crust of the Earth influencing natural deformation and controlling man's attempt to utilize natural resources. In particular, brittle phenomena affect: (1) the production of hydrocarbons, which requires a knowledge of the properties of fractured rocks in reservoirs and boreholes and an understanding of hydrofracturing; (2) mining techniques which involve rock removal, underground stability, water flow, and safety; (3) earthquake prediction, which depends upon a knowledge of the mechanical properties in and adjacent to natural fault zones; (4) engineering site evaluation and utilization; (5) waste disposal of radioactive materials, which is contingent not only upon the brittle response of the rock, but upon fluid transport through the material. It is clear that it is not just the brittle response of the rocks, but how fractures influence fluid flow, geophysical measurements, and associated phenomena that makes this an important area of scientific research to

ISSN:8755-1209    

DOI:10.1029/RG017i006p01121

年代:1979

数据来源: WILEY

摘要:

Perhaps one of the most significant aspects of the earth's crust is that the cracks and cavities within the rocks are not dry. The presence of interstitial water and water vapor has a pronounced effect on many crack related properties of brittle rocks such as fracture strength, frictional strength, creep rate, static fatigue, seismic wave velocity, compressibility, resistivity, to name a few. Although the influence of water on geophysical properties has been known for many years, several recent developments have accentuated the need for more detailed information on the mechanical and chemical effects of pore water in natural situations. First, the energy crisis has focused attention on the development of new geothermal resources as well as the stability of various rock types in areas proposed for nuclear waste disposal.

ISSN:8755-1209    

DOI:10.1029/RG017i006p01132

年代:1979

数据来源: WILEY

摘要:

The goal of research on the high temperature deformation of rocks and minerals is to determine the stress and strain history of the crust and mantle—to interpret the structures observed in naturally deformed rocks, to interpret geophysical measurements, and to allow accurate modelling. This research thus includes experimental and theoretical studies, as well as studies of naturally deformed rocks. In the four years since the review by Carter [1975] the importance of this field has been emphasized by a number of special conferences, including a Royal Society Discussion on Creep of Engineering Materials and of the Earth [1977; Phil. Trans. Roy. Soc. London, series A, v. 288, 1–236]and a C.N.R.S. International Colloquium on Deformation Mechanisms in Minerals and Rocks [1979; Bull. Fr. Soc. Min. Crist., v. 102]. This field was reviewed by Carter [1976]and treated extensively in a book by Nicolas and Poirier [1976], but there have been a number of significant advances in our understanding in the past few ye

ISSN:8755-1209    

DOI:10.1029/RG017i006p01137

年代:1979

数据来源: WILEY

摘要:

A fundamental feature associated with the propagation of stress waves in all solids is absorption of energy, which usually results in a change of the shape of transient waveforms. Despite its importance, the processes by which mechanical wave energy is converted into heat, and its effect on seismic observations, have been poorly understood. Although considerable progress has been made during the past few years, seismic attenuation remains a controversial subject as there is still considerable disagreement between different authors about some of its most fundamental aspects.In the first section of this paper the progress in arriving at a general phenomenological description of wave propagation and related effects such as the frequency dependence of the elastic moduli and transient creep will be covered. It turns out that for most attenuation mechanisms that are significant in rocks, this can be treated relatively independent of the details of the particular physical mechanisms responsible for the energy dissipation, which are treated in the second section. The third section gives a review of experimental results.

ISSN:8755-1209    

DOI:10.1029/RG017i006p01155

年代:1979

数据来源: WILEY