| タイトル | Rb-Sr age of the Shergotty achondrite and implications for metamorphic resetting of isochron ages |
| 著者（英） | Bansal, B.; Wooden, J.; Nyquist, L. E.; Bogard, D. D.; Mckay, G.; Wiesmann, H. |
| 著者所属（英） | NASA Johnson Space Center|National Academy of Sciences - National Research Council|Lockheed Electronics Co. |
| 発行日 | 1979-07-01 |
| 言語 | eng |
| 内容記述 | The age of the Shergotty achondrite is determined by Rb-Sr isotope analysis and the metamorphic resetting of isochron ages, which is presumed to have occurred during a shock event in the history of the meteorite, is discussed. The isochron best fitting the Rb-Sr evolution diagram is found to correspond to an age of 165 million years, with an initial Sr-87/Sr-86 value of 0.72260. Different apparent ages obtained by the K-Ar and Sm-Nd methods are interpreted in terms of a model which quantifies the degree of resetting of internal isochron ages by low temperature solid state diffusion. On the basis of these considerations, it is concluded that Shergotty crystallized from a melt 650 million years ago, was shock heated to 300 to 400 C after its parent body was involved in a collision 165 million years ago, and was first exposed to cosmic rays two million years ago. |
| NASA分類 | LUNAR AND PLANETARY EXPLORATION |
| レポートNO | 79A45629 |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/426018 |
|
