Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium
The helium and neon isotopic compositions of olivines coming from a 11Ma old xenolith sampled at Mt. Hampton (West Antarctica) were analyzed by crushing and heating. The 4He/3He isotopic ratio obtained by crushing varies between 1340 and 6300 (R/Ra between 115 and 539) with 4He content around 3-5 10...
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ftunivevora:oai:dspace.uevora.pt:10174/2427 2024-09-15T17:42:52+00:00 Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium Moreira, Manuel Madureira, Pedro 2005 2217957 bytes application/pdf http://hdl.handle.net/10174/2427 eng eng Elsevier http://hdl.handle.net/10174/2427 Geochimica et Cosmochimica Acta livre Departamento de Geociências moreira@ipgp.fr pedro@uevora.pt 396 openAccess Cosmogenic He and Ne Olivine article 2005 ftunivevora 2024-07-11T03:37:57Z The helium and neon isotopic compositions of olivines coming from a 11Ma old xenolith sampled at Mt. Hampton (West Antarctica) were analyzed by crushing and heating. The 4He/3He isotopic ratio obtained by crushing varies between 1340 and 6300 (R/Ra between 115 and 539) with 4He content around 3-5 10-10 ccSTP/g confirming that cosmogenic helium can be extracted by crushing [Scarsi, 2000; Yocochi et al., 2004]. The neon also shows a clear cosmogenic origin (20Ne/22Ne down to 7.7 and 21Ne/22Ne>0.32) indicating that some cosmogenic neon can also be extracted by crushing out of the olivines. This result indicates that for samples that had been exposed for a long time (e.g. few Ma to Ga), a step crushing procedure may not give the mantle ratios without ambiguity and that measurement of neon can discriminate between cosmogenic and mantle origin of the 3He. Melting of the powder left after the crushing experiment gives 4He/3He ratio as low as 51±5 (R/Ra=14 230) and 21Ne/22Ne as high as 0.78, close to the cosmogenic end-member. Our results show that ~0.4% of the cosmogenic helium and ~0.3% of the cosmogenic neon can be extracted out of olivines by crushing Article in Journal/Newspaper Antarc* Antarctica West Antarctica Repositório Científico da Universidade de Évora |
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Open Polar |
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Repositório Científico da Universidade de Évora |
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ftunivevora |
language |
English |
topic |
Cosmogenic He and Ne Olivine |
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Cosmogenic He and Ne Olivine Moreira, Manuel Madureira, Pedro Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium |
topic_facet |
Cosmogenic He and Ne Olivine |
description |
The helium and neon isotopic compositions of olivines coming from a 11Ma old xenolith sampled at Mt. Hampton (West Antarctica) were analyzed by crushing and heating. The 4He/3He isotopic ratio obtained by crushing varies between 1340 and 6300 (R/Ra between 115 and 539) with 4He content around 3-5 10-10 ccSTP/g confirming that cosmogenic helium can be extracted by crushing [Scarsi, 2000; Yocochi et al., 2004]. The neon also shows a clear cosmogenic origin (20Ne/22Ne down to 7.7 and 21Ne/22Ne>0.32) indicating that some cosmogenic neon can also be extracted by crushing out of the olivines. This result indicates that for samples that had been exposed for a long time (e.g. few Ma to Ga), a step crushing procedure may not give the mantle ratios without ambiguity and that measurement of neon can discriminate between cosmogenic and mantle origin of the 3He. Melting of the powder left after the crushing experiment gives 4He/3He ratio as low as 51±5 (R/Ra=14 230) and 21Ne/22Ne as high as 0.78, close to the cosmogenic end-member. Our results show that ~0.4% of the cosmogenic helium and ~0.3% of the cosmogenic neon can be extracted out of olivines by crushing |
format |
Article in Journal/Newspaper |
author |
Moreira, Manuel Madureira, Pedro |
author_facet |
Moreira, Manuel Madureira, Pedro |
author_sort |
Moreira, Manuel |
title |
Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium |
title_short |
Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium |
title_full |
Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium |
title_fullStr |
Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium |
title_full_unstemmed |
Cosmogenic helium and neon extracted by crushing: A technique for discriminating between mantle and cosmogenic helium |
title_sort |
cosmogenic helium and neon extracted by crushing: a technique for discriminating between mantle and cosmogenic helium |
publisher |
Elsevier |
publishDate |
2005 |
url |
http://hdl.handle.net/10174/2427 |
genre |
Antarc* Antarctica West Antarctica |
genre_facet |
Antarc* Antarctica West Antarctica |
op_relation |
http://hdl.handle.net/10174/2427 Geochimica et Cosmochimica Acta livre Departamento de Geociências moreira@ipgp.fr pedro@uevora.pt 396 |
op_rights |
openAccess |
_version_ |
1810489654412050432 |