Hf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar system
Three ordinary chondrites, Forest Vale (H4), Ste. Marguerite (H4) and Richardton (H5) have been studied with 182Hf-182W system (t(1/2) = 9 million years [m.y.]) in order to provide constraints on the initial 182Hf/180Hf for the chondritic parent body and the solar system. All three samples display p...
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| Format: | Journal article |
| Language: | English |
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2000
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| _version_ | 1797061275179548672 |
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| author | Lee, D Halliday, A |
| author_facet | Lee, D Halliday, A |
| author_sort | Lee, D |
| collection | OXFORD |
| description | Three ordinary chondrites, Forest Vale (H4), Ste. Marguerite (H4) and Richardton (H5) have been studied with 182Hf-182W system (t(1/2) = 9 million years [m.y.]) in order to provide constraints on the initial 182Hf/180Hf for the chondritic parent body and the solar system. All three samples display positive correlations between 182W/184W and 180Hf/184W, providing confirmation that live 182Hf was present in these samples. The best-fit lines define comparable slopes, passing through, or close to, the data for the bulk carbonaceous chondrites Allende and Murchison. At the current level of resolution this indicates a common and well-mixed chondritic reservoir in terms of the Hf-W isotope system. Forest Vale yields the most precise results with an apparent initial 182Hf/180Hf of (1.87 ± 0.16) X 10-4 and an initial 182W/184W of 0.864710 ± 15. If the Pb-Pb phosphate age of Forest Vale (~ 5 m.y. younger than the Pb-Pb age of Allende CAI) is a formation age, the bulk solar system initial 182Hf/180Hf is estimated to be (2.75 ± 0.24) X 10-4, comparable to previous estimates based on the differences in W isotopic compositions between iron meteorites and the mean of carbonaceous chondrites. The solar system 182W/184W initial of 0.86457 ± 4 (ε(W) = -4.99 ± 0.46) is similar to the least radiogenic W reported for iron meteorites, suggesting an extremely early origin of their parent bodies and the segregation of metallic cores from planetesimals. The solar system 182Hf/180Hf initial obtained in this study is high relative to the initial abundances of other short-lived nuclides, including those with longer half-lives such as 129I (t(1/2) = 16 m.y.). However, this result is explicable with the model of Wasserburg et al. (Wasserburg, G.J., Busso, M., Gallino, R., 1996. Abundances of actinides and short-lived nonactinides in the interstellar medium: Diverse supernova sources for the r-processes. Astrophys. J. 466, L109-113) who have proposed that 182Hf is synthesized in the same r-process supernovae events that produced the actinides over most of galactic history. (C) 2000 Elsevier Science B.V. All rights reserved. |
| first_indexed | 2024-03-06T20:28:45Z |
| format | Journal article |
| id | oxford-uuid:3052e1bf-43af-4e68-8daf-f81009954e92 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T20:28:45Z |
| publishDate | 2000 |
| record_format | dspace |
| spelling | oxford-uuid:3052e1bf-43af-4e68-8daf-f81009954e922022-03-26T13:00:45ZHf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar systemJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:3052e1bf-43af-4e68-8daf-f81009954e92EnglishSymplectic Elements at Oxford2000Lee, DHalliday, AThree ordinary chondrites, Forest Vale (H4), Ste. Marguerite (H4) and Richardton (H5) have been studied with 182Hf-182W system (t(1/2) = 9 million years [m.y.]) in order to provide constraints on the initial 182Hf/180Hf for the chondritic parent body and the solar system. All three samples display positive correlations between 182W/184W and 180Hf/184W, providing confirmation that live 182Hf was present in these samples. The best-fit lines define comparable slopes, passing through, or close to, the data for the bulk carbonaceous chondrites Allende and Murchison. At the current level of resolution this indicates a common and well-mixed chondritic reservoir in terms of the Hf-W isotope system. Forest Vale yields the most precise results with an apparent initial 182Hf/180Hf of (1.87 ± 0.16) X 10-4 and an initial 182W/184W of 0.864710 ± 15. If the Pb-Pb phosphate age of Forest Vale (~ 5 m.y. younger than the Pb-Pb age of Allende CAI) is a formation age, the bulk solar system initial 182Hf/180Hf is estimated to be (2.75 ± 0.24) X 10-4, comparable to previous estimates based on the differences in W isotopic compositions between iron meteorites and the mean of carbonaceous chondrites. The solar system 182W/184W initial of 0.86457 ± 4 (ε(W) = -4.99 ± 0.46) is similar to the least radiogenic W reported for iron meteorites, suggesting an extremely early origin of their parent bodies and the segregation of metallic cores from planetesimals. The solar system 182Hf/180Hf initial obtained in this study is high relative to the initial abundances of other short-lived nuclides, including those with longer half-lives such as 129I (t(1/2) = 16 m.y.). However, this result is explicable with the model of Wasserburg et al. (Wasserburg, G.J., Busso, M., Gallino, R., 1996. Abundances of actinides and short-lived nonactinides in the interstellar medium: Diverse supernova sources for the r-processes. Astrophys. J. 466, L109-113) who have proposed that 182Hf is synthesized in the same r-process supernovae events that produced the actinides over most of galactic history. (C) 2000 Elsevier Science B.V. All rights reserved. |
| spellingShingle | Lee, D Halliday, A Hf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar system |
| title | Hf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar system |
| title_full | Hf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar system |
| title_fullStr | Hf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar system |
| title_full_unstemmed | Hf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar system |
| title_short | Hf-W internal isochrons for ordinary chondrites and the initial (182)Hf/(180)Hf Of the solar system |
| title_sort | hf w internal isochrons for ordinary chondrites and the initial 182 hf 180 hf of the solar system |
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