The degree to which efficient mixing of new material or losses of earlier accreted material to space characterize the growth of Earth-like planets is poorly constrained and probably changed with time. These processes can be studied by parallel modelling of data from different radiogenic isotope systems. The tungsten isotope composition of the silicate Earth yields a model timescale for accretion that is faster than current estimates based on terrestrial lead and xenon isotope data and strontium, tungsten and lead data for lunar samples. A probable explanation for this is that impacting core material did not always mix efficiently with the silicate portions of the Earth before being added to the Earth's core. Furthermore, tungsten and strontium isotope compositions of lunar samples provide evidence that the Moon-forming impacting protoplanet Theia was probably more like Mars, with a volatile-rich, oxidized mantle. Impact-driven erosion was probably a significant contributor to the variations in moderately volatile element abundance and oxidation found among the terrestrial planets.
机构:
Washington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA
Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63130 USAWashington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA
Fegley, Bruce, Jr.
Lodders, Katharina
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Washington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA
Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63130 USAWashington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA
Lodders, Katharina
Jacobson, Nathan S.
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NASA, Mat Div, Glenn Res Ctr, MS106-1,21000 Brookpark Rd, Cleveland, OH 44135 USAWashington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA
机构:
Univ Paris Diderot, Sorbonne Paris Cite, Inst Phys Globe Paris, CNRS, F-75005 Paris, FranceUniv Paris Diderot, Sorbonne Paris Cite, Inst Phys Globe Paris, CNRS, F-75005 Paris, France
Pringle, Emily A.
Moynier, Frederic
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Univ Paris Diderot, Sorbonne Paris Cite, Inst Phys Globe Paris, CNRS, F-75005 Paris, France
Inst Univ France, Paris, FranceUniv Paris Diderot, Sorbonne Paris Cite, Inst Phys Globe Paris, CNRS, F-75005 Paris, France
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MIT, 77 Massachusetts Ave, Cambridge, MA 02139 USAMIT, 77 Massachusetts Ave, Cambridge, MA 02139 USA
Biersteker, John B.
Schlichting, Hilke E.
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MIT, 77 Massachusetts Ave, Cambridge, MA 02139 USA
Univ Calif Los Angeles, 595 Charles E Young Dr East, Los Angeles, CA 90095 USAMIT, 77 Massachusetts Ave, Cambridge, MA 02139 USA