40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765
The ^<40>(Ar)-^<39>(Ar) ages have been determined for two chondrites (Y-74191,Y-75258), one howardite (Y-7308) and two eucrites (Y-74450,ALH-765) from Antarctica. Y-74191 (L3) shows a disturbed age spectrum with a maximum apparent age of 4506±31 Ma in the intermediate temperature fractio...
Main Author: | |
---|---|
Format: | Report |
Language: | English |
Published: |
Geological Institute, Faculty of Science, University of Tokyo
1981
|
Subjects: | |
Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1219 http://id.nii.ac.jp/1291/00001219/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1219&item_no=1&attribute_id=18&file_no=1 |
id |
ftnipr:oai:nipr.repo.nii.ac.jp:00001219 |
---|---|
record_format |
openpolar |
spelling |
ftnipr:oai:nipr.repo.nii.ac.jp:00001219 2023-05-15T13:47:59+02:00 40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765 Ichiro Kaneoka 1981-12 https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1219 http://id.nii.ac.jp/1291/00001219/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1219&item_no=1&attribute_id=18&file_no=1 en eng Geological Institute, Faculty of Science, University of Tokyo https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1219 http://id.nii.ac.jp/1291/00001219/ AA00733561 Memoirs of National Institute of Polar Research. Special issue, 20, 250-263(1981-12) https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1219&item_no=1&attribute_id=18&file_no=1 Departmental Bulletin Paper P(論文) 1981 ftnipr 2022-11-12T19:42:05Z The ^<40>(Ar)-^<39>(Ar) ages have been determined for two chondrites (Y-74191,Y-75258), one howardite (Y-7308) and two eucrites (Y-74450,ALH-765) from Antarctica. Y-74191 (L3) shows a disturbed age spectrum with a maximum apparent age of 4506±31 Ma in the intermediate temperature fraction. Y-75258 (LL6) shows a plateau age of 4377±14 Ma at higher temperatures except for the highest temperature fraction. A howardite Y-7308 has an inversed age spectrum, but the intermediate temperature fractions indicate a plateau-like age of 4480±30 Ma. The apparent very old age at the lowest temperature might have been caused either by the effect of atmospheric contamination to the sample or by the redistribution of radiogenic ^<40>(Ar) in the sample. One eucrite Y-74450 shows a plateau age of 4012±22 Ma, indicating a later thermal event on the parent body of the meteorite. The other eucrite ALH-765 indicates a gradual increase in the apparent ^<40>(Ar)-^<39>(Ar) ages with increasing degassing temperature, but even the highest temperature fraction shows an age of about 3700 Ma. The present results together with those of reported ^<40>(Ar)-^<39>(Ar) and K-Ar ages suggest that meteorites found in Antarctica represent thermal histories very different from one another. Report Antarc* Antarctic Antarctica Memoirs of National Institute of Polar Research Polar Research National Institute of Polar Research Repository, Japan Antarctic |
institution |
Open Polar |
collection |
National Institute of Polar Research Repository, Japan |
op_collection_id |
ftnipr |
language |
English |
description |
The ^<40>(Ar)-^<39>(Ar) ages have been determined for two chondrites (Y-74191,Y-75258), one howardite (Y-7308) and two eucrites (Y-74450,ALH-765) from Antarctica. Y-74191 (L3) shows a disturbed age spectrum with a maximum apparent age of 4506±31 Ma in the intermediate temperature fraction. Y-75258 (LL6) shows a plateau age of 4377±14 Ma at higher temperatures except for the highest temperature fraction. A howardite Y-7308 has an inversed age spectrum, but the intermediate temperature fractions indicate a plateau-like age of 4480±30 Ma. The apparent very old age at the lowest temperature might have been caused either by the effect of atmospheric contamination to the sample or by the redistribution of radiogenic ^<40>(Ar) in the sample. One eucrite Y-74450 shows a plateau age of 4012±22 Ma, indicating a later thermal event on the parent body of the meteorite. The other eucrite ALH-765 indicates a gradual increase in the apparent ^<40>(Ar)-^<39>(Ar) ages with increasing degassing temperature, but even the highest temperature fraction shows an age of about 3700 Ma. The present results together with those of reported ^<40>(Ar)-^<39>(Ar) and K-Ar ages suggest that meteorites found in Antarctica represent thermal histories very different from one another. |
format |
Report |
author |
Ichiro Kaneoka |
spellingShingle |
Ichiro Kaneoka 40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765 |
author_facet |
Ichiro Kaneoka |
author_sort |
Ichiro Kaneoka |
title |
40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765 |
title_short |
40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765 |
title_full |
40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765 |
title_fullStr |
40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765 |
title_full_unstemmed |
40Ar-39Ar ages of Antarctic meteorites: Y-74191, Y-75258, Y-7308, Y-74450 and ALH-765 |
title_sort |
40ar-39ar ages of antarctic meteorites: y-74191, y-75258, y-7308, y-74450 and alh-765 |
publisher |
Geological Institute, Faculty of Science, University of Tokyo |
publishDate |
1981 |
url |
https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1219 http://id.nii.ac.jp/1291/00001219/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1219&item_no=1&attribute_id=18&file_no=1 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctica Memoirs of National Institute of Polar Research Polar Research |
genre_facet |
Antarc* Antarctic Antarctica Memoirs of National Institute of Polar Research Polar Research |
op_relation |
https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1219 http://id.nii.ac.jp/1291/00001219/ AA00733561 Memoirs of National Institute of Polar Research. Special issue, 20, 250-263(1981-12) https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1219&item_no=1&attribute_id=18&file_no=1 |
_version_ |
1766248249632489472 |