Regolith history of the aubritic meteorite parent body revealed by neutron capture effects on Sm and Gd isotopes
Use this link to cite this item : https://ir.lib.hiroshima-u.ac.jp/00015029
ID | 15029 |
file | |
creator |
Yoneda, Shigekazu
Marti, Kurt
|
NDC |
Astronomy. Space sciences
|
abstract | Enstatite achondrites (aubrites) when compared to other stone meteorites have unusually long cosmic-ray exposure (CRE) ages. We report here the 150Sm/149Sm and 158Gd/157Gd ratios in six different structural phases, i.e., light and dark (shocked) grains and in matrix materials of Pesyanoe, in three different fragments from Pena Blanca Spring, and in one from Norton County, Shallowater, and Khor Temiki, to investigate the regolith history on the aubrite parent body. The results from phases components of Pesyanoe confirm earlier reported evidence for regolith irradiation of several aubrites. The inferred neutron fluences for six Pesyanoe separates vary between (2.13 and 2.82) × 1016 n cm-2. The fluences also significantly exceed those expected from cosmic-ray irradiation during transit to Earth and approach those observed in the lunar regolith. These observations confirm that the brecciated Pesyanoe meteorite, which contains solar wind (SW) gases only in dark phases, was processed in a regolith and that structural phases were differentially irradiated before compaction. On the other hand, in some aubrites (Mt. Egerton, Shallowater, Pena Blanca Spring, Norton County) neutron capture effects may entirely be due to space irradiation.
|
journal title |
Geochimica et Cosmochimica Acta
|
volume | Volume 70
|
issue | Issue 13
|
start page | 3449
|
end page | 3456
|
date of issued | 2006-07
|
publisher | Elsevier Inc.
|
issn | 0016-7037
|
ncid | |
publisher doi | |
language |
eng
|
nii type |
Journal Article
|
HU type |
Journal Articles
|
DCMI type | text
|
format | application/pdf
|
text version | author
|
rights | Copyright (c) 2006 Elsevier Inc.
|
relation is version of URL | http://dx.doi.org/10.1016/j.gca.2006.04.009
|
department |
Graduate School of Science
|
Last 12 months's access : ? times
Last 12 months's DL: ? times
This month's access: ? times
This month's DL: ? times