Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean
The chronology and origin of volcanism of Ascension Island, South Atlantic Ocean, is poorly resolved. Here we use in situ produced cosmogenic 3He in olivine and pyroxene phenocrysts from well-preserved lava flows to date the main sub-aerial basalt volcanism on the island. Etching olivine separates i...
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ftuglasgow:oai:eprints.gla.ac.uk:78119 2023-05-15T18:21:05+02:00 Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean Ammon, K. Dunai, T.J. Stuart, F.M. Meriaux, A.-S. Gayer, E. 2009-12 http://eprints.gla.ac.uk/78119/ unknown Ammon, K., Dunai, T.J., Stuart, F.M. <http://eprints.gla.ac.uk/view/author/5291.html> , Meriaux, A.-S. and Gayer, E. (2009) Cosmogenic 3He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean. Quaternary Geochronology <http://eprints.gla.ac.uk/view/journal_volume/Quaternary_Geochronology.html>, 4(6), pp. 525-532. (doi:10.1016/j.quageo.2009.09.003 <http://dx.doi.org/10.1016/j.quageo.2009.09.003>) Articles PeerReviewed 2009 ftuglasgow https://doi.org/10.1016/j.quageo.2009.09.003 2021-09-23T22:54:55Z The chronology and origin of volcanism of Ascension Island, South Atlantic Ocean, is poorly resolved. Here we use in situ produced cosmogenic 3He in olivine and pyroxene phenocrysts from well-preserved lava flows to date the main sub-aerial basalt volcanism on the island. Etching olivine separates in HF/HNO3 appears to remove a significant proportion of the implanted radiogenic 4He contribution. Average exposure ages of each flow corrected for radiogenic He range from 328 ka to 186 ka and are used to refine the chronology and stratigraphy of the island. Magmatic 3He/4He ratios derived from in vacuo crushing are in the range of 6.3–7.3 RA. This range is lower than the neighbouring Mid-Atlantic Ridge segment (6–8°S) but slightly higher than measured in regional ocean islands of St. Helena, Tristan da Cunha and Gough. Combining these data with new trace element data and published radiogenic isotope ratios it appears that the Ascension Island magmatism is a mix of HIMU mantle material, typified by basalts from St. Helena, and depleted MORB-source mantle. Article in Journal/Newspaper South Atlantic Ocean University of Glasgow: Enlighten - Publications Gough ENVELOPE(159.367,159.367,-81.633,-81.633) Mid-Atlantic Ridge St. Helena ENVELOPE(8.575,8.575,63.621,63.621) Tristan ENVELOPE(140.900,140.900,-66.735,-66.735) Quaternary Geochronology 4 6 525 532 |
institution |
Open Polar |
collection |
University of Glasgow: Enlighten - Publications |
op_collection_id |
ftuglasgow |
language |
unknown |
description |
The chronology and origin of volcanism of Ascension Island, South Atlantic Ocean, is poorly resolved. Here we use in situ produced cosmogenic 3He in olivine and pyroxene phenocrysts from well-preserved lava flows to date the main sub-aerial basalt volcanism on the island. Etching olivine separates in HF/HNO3 appears to remove a significant proportion of the implanted radiogenic 4He contribution. Average exposure ages of each flow corrected for radiogenic He range from 328 ka to 186 ka and are used to refine the chronology and stratigraphy of the island. Magmatic 3He/4He ratios derived from in vacuo crushing are in the range of 6.3–7.3 RA. This range is lower than the neighbouring Mid-Atlantic Ridge segment (6–8°S) but slightly higher than measured in regional ocean islands of St. Helena, Tristan da Cunha and Gough. Combining these data with new trace element data and published radiogenic isotope ratios it appears that the Ascension Island magmatism is a mix of HIMU mantle material, typified by basalts from St. Helena, and depleted MORB-source mantle. |
format |
Article in Journal/Newspaper |
author |
Ammon, K. Dunai, T.J. Stuart, F.M. Meriaux, A.-S. Gayer, E. |
spellingShingle |
Ammon, K. Dunai, T.J. Stuart, F.M. Meriaux, A.-S. Gayer, E. Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean |
author_facet |
Ammon, K. Dunai, T.J. Stuart, F.M. Meriaux, A.-S. Gayer, E. |
author_sort |
Ammon, K. |
title |
Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean |
title_short |
Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean |
title_full |
Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean |
title_fullStr |
Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean |
title_full_unstemmed |
Cosmogenic 3 He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean |
title_sort |
cosmogenic 3 he exposure ages and geochemistry of basalts from ascension island, atlantic ocean |
publishDate |
2009 |
url |
http://eprints.gla.ac.uk/78119/ |
long_lat |
ENVELOPE(159.367,159.367,-81.633,-81.633) ENVELOPE(8.575,8.575,63.621,63.621) ENVELOPE(140.900,140.900,-66.735,-66.735) |
geographic |
Gough Mid-Atlantic Ridge St. Helena Tristan |
geographic_facet |
Gough Mid-Atlantic Ridge St. Helena Tristan |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_relation |
Ammon, K., Dunai, T.J., Stuart, F.M. <http://eprints.gla.ac.uk/view/author/5291.html> , Meriaux, A.-S. and Gayer, E. (2009) Cosmogenic 3He exposure ages and geochemistry of basalts from Ascension Island, Atlantic Ocean. Quaternary Geochronology <http://eprints.gla.ac.uk/view/journal_volume/Quaternary_Geochronology.html>, 4(6), pp. 525-532. (doi:10.1016/j.quageo.2009.09.003 <http://dx.doi.org/10.1016/j.quageo.2009.09.003>) |
op_doi |
https://doi.org/10.1016/j.quageo.2009.09.003 |
container_title |
Quaternary Geochronology |
container_volume |
4 |
container_issue |
6 |
container_start_page |
525 |
op_container_end_page |
532 |
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1766200159323029504 |