نتایج جستجو برای: tectonics
تعداد نتایج: 3578 فیلتر نتایج به سال:
Today, plate tectonics is the dominant tectonic style on Earth, but in a hotter Earth tectonics may have looked different due to the presence of more melting and associated compositional buoyancy as well as the presence of a weaker mantle and lithosphere. Here we review the geodynamic constraints on plate tectonics and proposed alternatives throughout Earth’s history. Observations suggest a 100...
Earth is the only known planet with subduction zones and plate tectonics, and this fact demonstrates that special conditions are required for this mode of planetary heat loss. Sinking of cold, dense lithosphere in subduction zones is the principal plate-driving force, so plate tectonics could not have begun until Earth cooled sufficiently to allow lithosphere to collapse into the underlying ast...
The inception of plate tectonics on Earth and its subsequent evolution are discussed on the basis of theoretical considerations and observational constraints. The likelihood of plate tectonics in the past depends on what mechanism is responsible for the relatively constant surface heat flux that is indicated by the likely thermal history of Earth. The continuous operation of plate tectonics thr...
New Horizons images of Pluto's companion Charon show a variety of terrains that display extensional tectonic features, with relief surprising for this relatively small world. These features suggest a global extensional areal strain of order 1% early in Charon's history. Such extension is consistent with the presence of an ancient global ocean, now frozen.
The explosion in GIS usage in marine disciplines such as active tectonics has revolutionised our ability to visualise, analyse, and interpret seafloor environments using multiple datasets and a much more “holistic” view of geologic/geophysical data than previously available. Driven by the growing capabilities of desktop workstations, we can now realistically expect to display, merge, and fly th...
Plate tectonics is largely responsible for material and heat circulation in Earth, but for unknown reasons it does not exist on Venus. The strength of planetary materials is a key control on plate tectonics because physical properties, such as temperature, pressure, stress, and chemical composition, result in strong rheological layering and convection in planetary interiors. Our deformation exp...
The realization that Earth may have lost heat more slowly in the past than at present has motivated the search for mechanisms to reduce the efficiency of plate tectonics in the past. Several mechanisms have been proposed, such as the resistance to subduction of thick plates (1) produced by deeper melting at higher mantle temperatures (2). We (3) proposed an alternative mechanism, namely subduct...
The evolution of Mars has been greatly influenced by temporal changes in its rheological structure, which may explain the difference in tectonics between Mars and Earth. Some previous studies have shown the rheological structures of Mars calculated from the flow law of rocks and the predicted thermal structure. However, the Peierls mechanism, which is the dominant deformation mechanism at relat...
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