Scientists have long held the belief that the fracturing of the Earth’s brittle outer shell into faults along the deep ocean’s mountainous landscape occurs only during long periods when no magma has intruded. Challenging this predominant theory, findings from a completed study show how differences in mid-ocean ridge magma-induced activity produce distinctly different types of ocean floor faulting. W. Roger Buck, Doherty Senior Research Scientist at the Lamont-Doherty Earth Observatory (LDEO), is one of a trio of scientists who developed these new models for faults seen at mid-ocean ridges where the Earth’s tectonic plates split apart and basaltic magma rises to form the oceanic crust that today covers two-thirds of the planet. The scientists’ work has culminated in the publishing of their findings in the April 7, 2005 issue of Nature.
Unlike faults on land, those formed along mid-ocean ridges are practically a dime a dozen. "The rate of fault generation across these ridges is a hundred times greater than on land," explains Buck. "And while land faults are easily eroded and often cut older faults in complex, hard-to-untangle ways, submarine faults break into newly formed crust and lithosphere and are little obscured by erosion. Recent observations show a huge range of fault types and sizes at ridges." These combined factors make mid-ocean ridges "the place to learn about how faults form and grow."
The team’s findings challenge the standard view that all faults at these ridges result from tectonic stretching of thin near-ridge lithosphere (the Earth’s brittle outer shell, where earthquakes are concentrated) in the absence of magma, hot molten rock from deep within the Earth. Among several recent observations that do not fit this standard model, two stand out: the first concerns where the faults form and the second deals with how far the faults slip. Faults formed at fast-spreading centers, like the East Pacific Rise, are tiny in comparison to faults that bound deep ocean hills at slow-spreading centers like the Mid-Atlantic Ridge. All ridge faults start off growing close to the ridge. Mid-Atlantic faults die only a short distance from where they are formed. In comparison, faults along the East Pacific Rise continue growing--although very slowly--much farther from the ridge axis. The new models show that these faults may form due to bending, not stretching, of the lithosphere.
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Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
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Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
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A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
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