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  • 1
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    Oxygen isotope exchange between refractory inclusion in Allende and solar nebula gas (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1998-12-04
    Description: A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope composition (approximately 5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). Some of the melilite is also anomalously enriched in oxygen-16 compared with oxygen isotopes measured in other CAIs. The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope exchange with the surrounding oxygen-16-poor nebular gas progressed through the crystallization of the CAI. Additional oxygen isotope exchange also occurred during subsequent reheating events in the solar nebula.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yurimoto, H -- Ito, M -- Nagasawa, H -- New York, N.Y. -- Science. 1998 Dec 4;282(5395):1874-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Japan. yuri@geo.titech.ac.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9874638" target="_blank"〉PubMed〈/a〉
    Keywords: Crystallization ; *Meteoroids ; Oxygen/*analysis ; Oxygen Isotopes/*analysis ; *Solar System
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Remnants of the early solar system water enriched in heavy oxygen isotopes (2007)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2007-06-16
    Description: Oxygen isotopic composition of our solar system is believed to have resulted from mixing of two isotopically distinct nebular reservoirs, 16O-rich and (17,18)O-rich relative to Earth. The nature and composition of the (17,18)O-rich reservoir are poorly constrained. We report an in situ discovery of a chemically and isotopically unique material distributed ubiquitously in fine-grained matrix of a primitive carbonaceous chondrite Acfer 094. This material formed by oxidation of Fe,Ni-metal and sulfides by water either in the solar nebula or on a planetesimal. Oxygen isotopic composition of this material indicates that the water was highly enriched in 17O and 18O (delta(17,18)O(SMOW) = +180 per thousand per mil), providing the first evidence for an extremely (17,18)O-rich reservoir in the early solar system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sakamoto, Naoya -- Seto, Yusuke -- Itoh, Shoichi -- Kuramoto, Kiyoshi -- Fujino, Kiyoshi -- Nagashima, Kazuhide -- Krot, Alexander N -- Yurimoto, Hisayoshi -- New York, N.Y. -- Science. 2007 Jul 13;317(5835):231-3. Epub 2007 Jun 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Natural History Sciences, Hokkaido University, Sapporo 060-0810, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17569827" target="_blank"〉PubMed〈/a〉
    Keywords: *Meteoroids ; Oxidation-Reduction ; Oxygen/*analysis ; Oxygen Isotopes/*analysis ; *Solar System ; Water/*chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Molecular cloud origin for the oxygen isotope heterogeneity in the solar system (2004)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2004-09-18
    Description: Meteorites and their components have anomalous oxygen isotopic compositions characterized by large variations in 18O/16O and 17O/16O ratios. On the basis of recent observations of star-forming regions and models of accreting protoplanetary disks, we suggest that these variations may originate in a parent molecular cloud by ultraviolet photodissociation processes. Materials with anomalous isotopic compositions were then transported into the solar nebula by icy dust grains during the collapse of the cloud. The icy dust grains drifted toward the Sun in the disk, and their subsequent evaporation resulted in the 17O- and 18O-enrichment of the inner disk gas.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yurimoto, Hisayoshi -- Kuramoto, Kiyoshi -- New York, N.Y. -- Science. 2004 Sep 17;305(5691):1763-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan. yuri@geo.titech.ac.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15375265" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon Isotopes ; Carbon Monoxide ; Cosmic Dust ; Ice ; *Oxygen Isotopes ; Photochemistry ; Photons ; *Solar System ; Temperature ; Ultraviolet Rays
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
    Electronic Resource
    Electronic Resource
    Co2+ and Ni2+ diffusion in olivine determined by secondary ion mass spectrometry (1999)
    Springer
    Physics and chemistry of minerals 26 (1999), S. 425-431 
    Details
    ISSN: 1432-2021
    Keywords: Key words SIMS ; Depth profiling ; Forsterite Diffusion ; Arrhenius plot ; Activation energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Diffusion coefficients of Co2+ and Ni2+ in synthetic single crystal forsterite along the c-axis were determined in the temperature ranges, 700–1200 °C and 800–1300 °C, respectively. The synthesized forsterite specimens were coated with thin evaporated films of CoO and NiO on the c-surface and annealed for diffusion experiments. The short penetration distance of diffusing ions in forsterite was measured by secondary ion mass spectrometry using the depth profile method. The diffusion coefficients of Co (700–1200 °C) and Ni (800–1300 °C) are given by: and The observed diffusion coefficient values show good linear relationships in Arrhenius plots and the activation energy values obtained agree well with the previous values, although the diffusion coefficient values observed at the high temperature end of the experimental range deviate from the previous values. These results indicate that Co and Ni diffuse in olivine with a single mechanism within the temperature range observed, possibly with an extrinsic in nature as in the case of Mg tracer diffusion observed by Chakraborty et al. 1994 and of Fe-Mg interdiffusion by Chakraborty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690050204
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  • 5
    Electronic Resource
    Electronic Resource
    Stability of dense hydrous magnesium silicate phases in the systems Mg2SiO4-H2O and MgSiO3-H2O at pressures up to 27 GPa (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 533-544 
    Details
    ISSN: 1432-2021
    Keywords: Key words High pressure ; High temperature ; DHMS ; phases A ; G
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract We conducted high-pressure phase equilibrium experiments in the systems MgSiO3 with 15 wt% H2O and Mg2SiO4 with 5 wt% and 11 wt% H2O at 20 ∼ 27 GPa. Based on the phase relations in these systems, together with the previous works on the related systems, we have clarified the stability relations of dense hydrous magnesium silicates in the system MgO-SiO2-H2O in the pressure range from 10 to 27 GPa. The results show that the stability field of phase G, which is identical to phase D and phase F, expands with increasing water contents. Water stored in serpentine in the descending cold slabs is transported into depths greater than 200 km, where serpentine decomposes to a mixture of phase A, enstatite, and fluid. Reaction sequences of the hydrous phases which appear at higher pressures vary with water content. In the slabs with a water content less than about 2 wt%, phase A carries water to a depth of 450 km. Hydrous wadsleyite, hydrous ringwoodite, and ilmenite are the main water reservoirs in the transition zone from 450 to 660 km. Superhydrous phase B is the water reservoir in the uppermost part of the lower mantle from 670 to 800 km, whereas phase G appears in the lower mantle only at depths greater than 800 km. In cold slabs with local water enrichment greater than 2 wt%, the following hydrous phases appear with increasing depths; phase A to 450 km, phase A and phase G from 450 km to 550 km, brucite, superhydrous phase B, and phase G from 550 km to 800 km, and phase G at depths greater than 800 km.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690000097
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