Hf-w dating

This allows lots of Hf to decay to W, leading to epsilon-tungsten larger than zero. There are complicating factors that give cosmochemists the opportunity of delving more deeply into the processes involved in the initial differentiation of the planets. One of those is the behavior of the Hf and W left behind in the rocky portion. Shearer and Righter did experiments to quantify the behavior of W during the melting of silicates rocks. Iron meteorites like the one shown here formed when chondrites melted. The metal, because it was denser than the surrounding silicates, sank to form the core of a tiny planet in the asteroid belt.

Because the hafnium stayed behind, there was no source of W, giving a value of epsilon-tungsten less than 0. To determine the behavior of tungsten at high temperature and pressure, Kevin Righter used high-pressure apparatus at the University of Arizona. The samples to be studied were placed in the center of ceramic octahedral white and then squeezed between eight truncated tungsten carbide cubes grayish, metallic. The tungsten does not interfere with the experiments on the behavior of tungsten inside the ceramic octahedral.

Depending on the sizes of the octahedrons and the truncations on the tungsten carbide cubes, pressures between 3 and 30 billion pascals 30, to , times atmospheric pressure can be obtained. This corresponds to depths of about to km on Earth and to km on Mars. The assembled stack of eight cubes and the sample octahedron is placed in the center of this cylindrical module, between six wedges that are connected to a hydraulic system.

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The blue module is called a "multi-anvil module. The multi-anvil module is placed into a ton press in the laboratory of Professor Mike Drake right at the University of Arizona. Drake is a pioneer in determining partitioning behavior of trace elements from high-temperature and high-pressure experiments. Nancy Chabot left and Chris Capobianco right , then at the University of Arizona, observe a sample being pressurized.

The concentrations of tungsten were measured with the ion microprobe at the University of New Mexico. This complicated instrument consists of an ion source, mass spectrometer, and associated electronics and vacuum system. Such rocks could form late during the solidification of the lunar magma ocean. When rocks rich in ilmenite and high-calcium pyroxene melted, the magma would also have high epsilon-tungsten.

Residual elements were eluted sequentially with 5 c. A blank correction was applied to all samples, and the uncertainty of this correction is propagated in the final uncertainties of the isotope measurements reported in Table 1. Wasserburg for comments on an earlier version of this paper. We also thank Andy Davis and two anonymous referees for their constructive comments, which improved the quality of this paper.

The authors declare no conflict of interest. This article contains supporting information online at www. National Center for Biotechnology Information , U. Published online May Holst , a Mia B. Larsen , a James N. Connelly , a Jes K.

Author information Copyright and License information Disclaimer. Edited by Neta A. This article has been cited by other articles in PMC. Abstract Refractory inclusions [calcium—aluminum-rich inclusions, CAIs ] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. Open in a separate window. Supplementary Material Supporting Information: Click here to view. Acknowledgments We thank G.

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Footnotes The authors declare no conflict of interest. Short-lived radionuclides in the early solar system: Connelly JN, et al.

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The absolute chronology and thermal processing of solids in the solar protoplanetary disk. Chondrites and the Protoplanetary Disk. Astrophysical Society of the Pacific; Incorporation of short-lived 10 Be in a calcium-aluminum-rich inclusion from the allende meteorite. Treatise on Geochemistry 1. Krot AN, et al.

Hf-w dating Mississippi

Origin and chronology of chondritic components: Larsen KK, et al. Evidence for magnesium isotope heterogeneity in the solar protoplanetary disk. Liu M-C, et al. Isotopic records in CM hibonites: Implications of timescales for mixing of isotope reservoirs in the solar nebula. Makide K, et al. Heterogeneous distribution of 26 Al at the birth of the solar system.

Correlated O and Mg isotopic anomalies in Allende inclusions: Sahijpal S, Goswami JN. Refractory phases in primitive meteorites devoid of 26 Al and 41 Ca: Representative samples of first solar system solids? The identification of meteorite inclusions with isotope anomalies. Fractionation in the solar nebula: Condensation of yttrium and the rare earth elements. Kleine T, et al. Hf-W chronology of the accretion and early evolution of asteroids and terrestrial planets.

Early core formation in asteroids and late accretion of chondrite parent bodies: Burkhardt C, et al. Hf-W mineral isochron for Ca,Al-rich inclusions: Age of the solar system and the timing of core formation in planetesimals. Nucleosynthetic tungsten isotope anomalies in acid leachates of the Murchison meteorite: Implication for hafnium-tungsten chronometry. Chronology of the angrite parent body and implications for core formation in protoplanets.

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  • Hf-w dating - PerfectPixel Publicidad - Agencia de publicidad.
  • PSRD: Hafnium, Tungsten, and the Differentiation of the Moon and Mars.

Stellar sources of the short-lived radionuclides in the early solar system. Star formation efficiencies and lifetimes of giant molecular clouds in the Milky Way. Short-lived nuclei in the early solar system: Diehl R, et al. Radioactive 26 Al from massive stars in the Galaxy.

Meteoritic evidence for the infall of large interstellar dust aggregates during formation of the solar system. Trinquier A, et al.

Hf-w dating Mississippi

Origin of nucleosynthetic isotope heterogeneity in the solar protoplanetary disk. Extreme 50 Ti enrichments in primitive meteorites. Presolar isotopic and chemical signatures in hibonite-bearing refractory inclusions from the Murchison carbonaceous chondrite. Protoplanetary disks and their evolution. Annu Rev Astron Astrophys.


Evolution of the solar nebula. Gradients in the spatial heterogeneity of the short-lived radioisotopes 60 Fe and 26 Al and the stable oxygen isotopes. Oxygen isotopic composition of the sun and mean oxygen isotopic composition of the protosolar silicate dust: