The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data
The collection of helium isotopic data in the last twenty years has shown different signatures for MORB and OIB basalts and this has been used as the basis for the two-layer mantle model. However, for some OIB that appear in the vicinity of mid-ocean ridges, He isotopic ratios are similar to those t...
Main Authors: | , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Elsevier
2005
|
Subjects: | |
Online Access: | http://hdl.handle.net/10174/2447 |
id |
ftunivevora:oai:dspace.uevora.pt:10174/2447 |
---|---|
record_format |
openpolar |
spelling |
ftunivevora:oai:dspace.uevora.pt:10174/2447 2023-09-05T13:20:36+02:00 The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data Madureira, Pedro Moreira, Manuel Mata, João 2005-05 4697464 bytes application/pdf http://hdl.handle.net/10174/2447 eng eng Elsevier http://hdl.handle.net/10174/2447 Geochimica et Cosmochimica Acta livre Departamento de Geociências pedro@uevora.pt moreira@ipgp.fr jmata@fc.ul.pt 396 openAccess Neon isotopic data Azores hot spot article 2005 ftunivevora 2023-08-14T17:26:45Z The collection of helium isotopic data in the last twenty years has shown different signatures for MORB and OIB basalts and this has been used as the basis for the two-layer mantle model. However, for some OIB that appear in the vicinity of mid-ocean ridges, He isotopic ratios are similar to those typical of MORB, leading some authors to argue against the deep mantle plume hypothesis particularly in areas where geophysical evidence is lacking (Anderson, 2000). For Terceira island (Azores), located close to the Mid- Atlantic Ridge, we analysed neon from olivine phenocrysts in order to better constrain the nature of the Azorian plume. Some of the analysed samples show higher 20Ne/22Ne and 21Ne/22Ne ratios than air suggesting the presence of a mantle component in the olivine melt inclusions. Moreover, in a three-Ne isotope diagram, the samples define a trend with a higher slope than the MORB line (Sarda et al., 1988) arguing for a lower mantle origin. One basaltic sample coming from the 1998 submarine Serreta eruption is plotted along this line, suggesting that the influence of a deep plume is still active. In a plot of 21Ne/22Necorr vs. 4He/3He, Terceira data is plotted in the same hyperbolic mixing line that encompasses Iceland, Shona and Discovery data (Moreira et al., 1995, 2001; Sarda et al., 2000). The data suggests the existence of plume-ridge interaction for these hotspots resulting on mixing between degassed MORB-type and deep plume-type magmas. In such an environment the data shows that neon is a better tracer of primordial material than helium. Article in Journal/Newspaper Iceland Repositório Científico da Universidade de Évora Mid-Atlantic Ridge |
institution |
Open Polar |
collection |
Repositório Científico da Universidade de Évora |
op_collection_id |
ftunivevora |
language |
English |
topic |
Neon isotopic data Azores hot spot |
spellingShingle |
Neon isotopic data Azores hot spot Madureira, Pedro Moreira, Manuel Mata, João The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data |
topic_facet |
Neon isotopic data Azores hot spot |
description |
The collection of helium isotopic data in the last twenty years has shown different signatures for MORB and OIB basalts and this has been used as the basis for the two-layer mantle model. However, for some OIB that appear in the vicinity of mid-ocean ridges, He isotopic ratios are similar to those typical of MORB, leading some authors to argue against the deep mantle plume hypothesis particularly in areas where geophysical evidence is lacking (Anderson, 2000). For Terceira island (Azores), located close to the Mid- Atlantic Ridge, we analysed neon from olivine phenocrysts in order to better constrain the nature of the Azorian plume. Some of the analysed samples show higher 20Ne/22Ne and 21Ne/22Ne ratios than air suggesting the presence of a mantle component in the olivine melt inclusions. Moreover, in a three-Ne isotope diagram, the samples define a trend with a higher slope than the MORB line (Sarda et al., 1988) arguing for a lower mantle origin. One basaltic sample coming from the 1998 submarine Serreta eruption is plotted along this line, suggesting that the influence of a deep plume is still active. In a plot of 21Ne/22Necorr vs. 4He/3He, Terceira data is plotted in the same hyperbolic mixing line that encompasses Iceland, Shona and Discovery data (Moreira et al., 1995, 2001; Sarda et al., 2000). The data suggests the existence of plume-ridge interaction for these hotspots resulting on mixing between degassed MORB-type and deep plume-type magmas. In such an environment the data shows that neon is a better tracer of primordial material than helium. |
format |
Article in Journal/Newspaper |
author |
Madureira, Pedro Moreira, Manuel Mata, João |
author_facet |
Madureira, Pedro Moreira, Manuel Mata, João |
author_sort |
Madureira, Pedro |
title |
The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data |
title_short |
The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data |
title_full |
The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data |
title_fullStr |
The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data |
title_full_unstemmed |
The Azores hotspot: A lower mantle origin for Terceira magmas as shown by Ne isotopic data |
title_sort |
azores hotspot: a lower mantle origin for terceira magmas as shown by ne isotopic data |
publisher |
Elsevier |
publishDate |
2005 |
url |
http://hdl.handle.net/10174/2447 |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
http://hdl.handle.net/10174/2447 Geochimica et Cosmochimica Acta livre Departamento de Geociências pedro@uevora.pt moreira@ipgp.fr jmata@fc.ul.pt 396 |
op_rights |
openAccess |
_version_ |
1776201252412063744 |