Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt Geochemistry
Abstract Hawaiian volcanoes belong to two geographically and geochemically distinct trends, the Loa and Kea trends. The cause of this dichotomy is still strongly debated. One of the prevailing hypotheses is that the two trends originate in the deep mantle where the Hawaiian mantle plume straddles tw...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2020-11-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Online Access: | https://doi.org/10.1029/2020GC009292 |
| _version_ | 1797637926718275584 |
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| author | Dominique Weis Lauren N. Harrison Rhy McMillan Nicole M. B. Williamson |
| author_facet | Dominique Weis Lauren N. Harrison Rhy McMillan Nicole M. B. Williamson |
| author_sort | Dominique Weis |
| collection | DOAJ |
| description | Abstract Hawaiian volcanoes belong to two geographically and geochemically distinct trends, the Loa and Kea trends. The cause of this dichotomy is still strongly debated. One of the prevailing hypotheses is that the two trends originate in the deep mantle where the Hawaiian mantle plume straddles two geophysically and geochemically distinct domains at the core‐mantle boundary (CMB). New high‐precision multi‐isotopic (Pb, Hf, Nd, and Sr) compositions of lavas from three key volcanoes, Lō‘ihi, Kohala, and Haleakalā, show transitional signatures between Loa and Kea compositions that call into question the degree of physical independence between the two trends. Statistical analysis of multi‐collector inductively coupled plasma mass spectrometer or triple‐spike Pb (n > 800) and Sr, Nd, and Hf data (n > 400) for shield tholeiites from the entire Hawaiian Islands (<5.5 Ma) identifies six unique geochemical groups, and for the first time, documents large‐scale heterogeneities in the Kea trend. The spatial orientation of the six geochemical groups shows that the bilateral zonation of the plume source at the CMB is gradational, and that the Hawaiian mantle plume periodically entrains large‐scale ephemeral geochemical heterogeneities on million‐year, regional timescales. These geochemical heterogeneities are stretched vertically during transit of the plume to the surface and are observed in the lavas from the Hawaiian Islands. These results provide evidence that the large low shear velocity province in the deep Pacific is thermochemical and highly heterogeneous. |
| first_indexed | 2024-03-11T12:55:17Z |
| format | Article |
| id | doaj.art-2249a2e28b8a465db0bbcd9e76d4019d |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:55:17Z |
| publishDate | 2020-11-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-2249a2e28b8a465db0bbcd9e76d4019d2023-11-03T17:01:17ZengWileyGeochemistry, Geophysics, Geosystems1525-20272020-11-012111n/an/a10.1029/2020GC009292Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt GeochemistryDominique Weis0Lauren N. Harrison1Rhy McMillan2Nicole M. B. Williamson3Pacific Centre for Isotopic and Geochemical Research Department of Earth, Ocean and Atmospheric Sciences University of British Columbia Vancouver BC CanadaNuclear and Chemical Sciences Lawrence Livermore National Lab Livermore CA USAPacific Centre for Isotopic and Geochemical Research Department of Earth, Ocean and Atmospheric Sciences University of British Columbia Vancouver BC CanadaPacific Centre for Isotopic and Geochemical Research Department of Earth, Ocean and Atmospheric Sciences University of British Columbia Vancouver BC CanadaAbstract Hawaiian volcanoes belong to two geographically and geochemically distinct trends, the Loa and Kea trends. The cause of this dichotomy is still strongly debated. One of the prevailing hypotheses is that the two trends originate in the deep mantle where the Hawaiian mantle plume straddles two geophysically and geochemically distinct domains at the core‐mantle boundary (CMB). New high‐precision multi‐isotopic (Pb, Hf, Nd, and Sr) compositions of lavas from three key volcanoes, Lō‘ihi, Kohala, and Haleakalā, show transitional signatures between Loa and Kea compositions that call into question the degree of physical independence between the two trends. Statistical analysis of multi‐collector inductively coupled plasma mass spectrometer or triple‐spike Pb (n > 800) and Sr, Nd, and Hf data (n > 400) for shield tholeiites from the entire Hawaiian Islands (<5.5 Ma) identifies six unique geochemical groups, and for the first time, documents large‐scale heterogeneities in the Kea trend. The spatial orientation of the six geochemical groups shows that the bilateral zonation of the plume source at the CMB is gradational, and that the Hawaiian mantle plume periodically entrains large‐scale ephemeral geochemical heterogeneities on million‐year, regional timescales. These geochemical heterogeneities are stretched vertically during transit of the plume to the surface and are observed in the lavas from the Hawaiian Islands. These results provide evidence that the large low shear velocity province in the deep Pacific is thermochemical and highly heterogeneous.https://doi.org/10.1029/2020GC009292 |
| spellingShingle | Dominique Weis Lauren N. Harrison Rhy McMillan Nicole M. B. Williamson Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt Geochemistry Geochemistry, Geophysics, Geosystems |
| title | Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt Geochemistry |
| title_full | Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt Geochemistry |
| title_fullStr | Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt Geochemistry |
| title_full_unstemmed | Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt Geochemistry |
| title_short | Fine‐Scale Structure of Earth's Deep Mantle Resolved Through Statistical Analysis of Hawaiian Basalt Geochemistry |
| title_sort | fine scale structure of earth s deep mantle resolved through statistical analysis of hawaiian basalt geochemistry |
| url | https://doi.org/10.1029/2020GC009292 |
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