Geology articles within Nature

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  • News & Views |

    Plate reconstructions show that ancient eruptions of diamond-bearing rocks occurred consistently above a ring-like region of plume-generation zones deep in Earth's mantle. Do such zones remain stationary?

    • David A. D. Evans

  • Letter |

    It has been proposed that the age of the Earth deduced from lead isotopes reflects loss of lead into space at the time of the Moon's formation rather than partitioning into metallic liquids during core formation. Here it is shown that lead partitioning into liquid iron depends strongly on carbon content and that, given a core carbon content of about 0.2%, there is evidence of strong partitioning of lead into the core throughout the Earth's accretion.

    • Bernard J. Wood
    •  & Alex N. Halliday

  • Letter |

    Here, global mantle flow is computed on the basis of recent, high-resolution seismic tomography, to investigate the role of buoyancy-driven and plate-motion-induced mantle circulation in the Mediterranean region. The findings show that mantle flow explains much of the observed dynamic topography and microplate motion in the region. Small-scale convection in the uppermost mantle may also hold the key to understanding complex mobile belts elsewhere.

    • Claudio Faccenna
    •  & Thorsten W. Becker

  • Letter |

    Here, first-principles methods have been applied to calculate diffusion rates in the mineral post-perovskite under the conditions found in the Earth's lower mantle. The results show that the diffusion of Mg2+ and Si4+ in post-perovskite is extremely anisotropic. This could render post-perovskite up to four orders of magnitude weaker than perovskite, and might reconcile seismic observations of a D” reflector with recent experiments showing that the perovskite to post-perovskite transition is too wide to cause sharp reflectors.

    • M. W. Ammann
    • , J. P. Brodholt
    •  & D. P. Dobson

  • Letter |

    The direction of tectonic plate motion at the Earth's surface and the flow field of the mantle inferred from seismic anisotropy are well correlated globally, implying large-scale coupling between the mantle and surface plates. But the fit is poor at subduction zones. Here, three-dimensional numerical models of buoyancy-driven deformation for the Alaska subduction–transform system are used to find the origin of the regional decoupling of flow. The results imply local rapid transport of geochemical signatures through subduction zones.

    • Margarete A. Jadamec
    •  & Magali I. Billen

  • Letter |

    Accelerated uplift and global cooling have been suggested as possible causes for a fourfold increase in global sedimentation rates, and by inference in erosion rates or weathering fluxes, during the past 5 million years. Here, proxy evidence is provided that indicates stable weathering fluxes in the late-Cenozoic era. It is proposed that processes different from an increase in denudation caused Cenozoic global cooling.

    • Jane K. Willenbring
    •  & Friedhelm von Blanckenburg

  • Letter |

    The magnetic field inside the Earth's outer core cannot be directly probed. The intensity of the magnetic field at the core–mantle boundary is estimated to be 0.3 mT, and geodynamo models predict a value about ten times larger (3 mT) for the core's interior. Other data, however, indicate an internal field of only around 0.2 mT. This discrepancy has now been resolved: an ensemble inversion of core flow models finds a torsional wave recurring every 6 years, leading to an estimated field strength of around 4 mT inside the core.

    • Nicolas Gillet
    • , Dominique Jault
    •  & Alexandre Fournier

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