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Post Info TOPIC: Tectonic Plates
Blobrana


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RE: Plate tectonics
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Flawed Diamonds Deliver Precious Details about Early Earth's Tectonics

These precious rocks occasionally contain impurities trapped inside during formation billions of years ago. And with the right tools, scientists can mine these traces for date details and chemical composition to get a rare snapshot of early Earth. From such miniscule grains - sulphides and silicate in a new analysis - a pair of researchers is now proposing a date for the beginning of the modern plate tectonic cycle: 3 billion years ago.
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Blobrana


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New subduction zone
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New subduction zone may increase quake risk in the Mediterranean

Europe may be starting to dive under Africa, creating a new subduction zone and potentially increasing the earthquake risk in the western Mediterranean Sea, scientists report.
Subduction zones form where tectonic plates collide, with one plate diving beneath the other and into Earth's mantle. Sometimes these collisions are gradual, but often they occur in big lurches that can trigger quakes.
For millions of years the African plate, which contains part of the Mediterranean seabed, has been moving northward toward the Eurasian Plate at a rate of about a centimetre a year.
Now studies of recent earthquakes in the region indicate that a new subduction zone may be forming where the plates are colliding along the coasts of Algeria and northern Sicily
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Blobrana


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RE: Tectonic Plates
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The role of crustal quartz in controlling Cordilleran deformation

Large-scale deformation of continents remains poorly understood more than 40years after the plate tectonic revolution. Rock flow strength and mass density variations both contribute to stress, so both are certain to be important, but these depend (somewhat nebulously) on rock type, temperature and whether or not unbound water is present. Hence, it is unclear precisely how Earth material properties translate to continental deformation zones ranging from tens to thousands of kilometres in width, why deforming zones are sometimes interspersed with non-deforming blocks and why large earthquakes occasionally rupture in otherwise stable continental interiors. An important clue comes from observations that mountain belts and rift zones cyclically form at the same locations despite separation across vast gulfs of time (dubbed the Wilson tectonic cycle), accompanied by inversion of extensional basins and reactivation of faults and other structures formed in previous deformation events. Here we show that the abundance of crustal quartz, the weakest mineral in continental rocks, may strongly condition continental temperature and deformation. We use EarthScope seismic receiver functions, gravity and surface heat flow measurements to estimate thickness and seismic velocity ratio, vP/vS, of continental crust in the western United States. The ratio vP/vS is relatively insensitive to temperature but very sensitive to quartz abundance. Our results demonstrate a surprising correlation of low crustal vP/vS with both higher lithospheric temperature and deformation of the Cordillera, the mountainous region of the western United States. The most plausible explanation for the relationship to temperature is a robust dynamical feedback, in which ductile strain first localises in relatively weak, quartz-rich crust, and then initiates processes that promote advective warming, hydration and further weakening. The feedback mechanism proposed here would not only explain stationarity and spatial distributions of deformation, but also lend insight into the timing and distribution of thermal uplift and observations of deep-derived fluids in springs

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Blobrana


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Computational scientists and geophysicists at the University of Texas at Austin and the California Institute of Technology (Caltech) have developed new computer algorithms that for the first time allow for the simultaneous modelling of the earth's Earth's mantle flow, large-scale tectonic plate motions, and the behaviour of individual fault zones, to produce an unprecedented view of plate tectonics and the forces that drive it.
A paper describing the whole-earth model and its underlying algorithms will be published in the August 27 issue of the journal Science and also featured on the cover.
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Blobrana


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Posts: 131433
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Plate tectonics
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Plate tectonics is the process of continents on the Earth drifting and colliding, rock grinding and scraping, mountain ranges being formed, and earthquakes tearing land apart. It makes our world dynamic and ever-changing. But should it factor into our search for life elsewhere in the universe?
Tilman Spohn believes so. As director of the German Space Research Centre Institute of Planetary Research, and chairman of ESA's scientific advisory committee, he studies worlds beyond our Earth. When looking into the relationship between habitability and plate tectonics, some fascinating possibilities emerged.

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