Helium and lead isotope geochemistry of the Azores Archipelago
New helium and lead isotopic data for basalts from the Azores archipelago (North Atlantic) show that the Azores have 4He/ 3He ratios both higher and lower than MORB values. Good covariations of helium and lead isotopes are observed at the scale of the archipelago, and suggest the coexistence of two...
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| Veröffentlicht in: | Earth and planetary science letters 1999-05, Vol.169 (1), p.189-205 |
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| creator | Moreira, Manuel Doucelance, Régis Kurz, Mark D. Dupré, Bernard Allègre, Claude Jean |
| description | New helium and lead isotopic data for basalts from the Azores archipelago (North Atlantic) show that the Azores have
4He/
3He ratios both higher and lower than MORB values. Good covariations of helium and lead isotopes are observed at the scale of the archipelago, and suggest the coexistence of two mantle components in the Azores which are identified by data from São Miguel and Terceira. The eastern part of São Miguel island displays radiogenic helium (
4He/
3He > 140,000,
R/
R
a100,000) were observed at latitude higher than 40°N and may reflect the influence of the São Miguel component at the ridge. |
| doi_str_mv | 10.1016/S0012-821X(99)00071-0 |
| format | Article |
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4He/
3He ratios both higher and lower than MORB values. Good covariations of helium and lead isotopes are observed at the scale of the archipelago, and suggest the coexistence of two mantle components in the Azores which are identified by data from São Miguel and Terceira. The eastern part of São Miguel island displays radiogenic helium (
4He/
3He > 140,000,
R/
R
a<5.1) and lead (20.00, 15.75 and 40.33 for
206Pb/
204Pb,
207Pb/
204Pb and
208Pb/
204Pb). The
207Pb/
204Pb and
208Pb/
204Pb ratios for São Miguel are unusually radiogenic for oceanic basalts. Terceira basalts contain relatively unradiogenic/primitive
4He/
3He ratios, with a minimum value of 64,000 (
R/
R
a=11.3), and relatively high lead isotopic ratios (
206Pb/
204Pb = 20.02,
207Pb/
204Pb = 15.64 and
208Pb/
204Pb = 39.35). We propose that the Terceira source has a composition produced by a mixing between recycled oceanic crust (high
206Pb/
204Pb) and entrained lower mantle (high
3He) material. The São Miguel island isotopic signature may be due to sampling of local (km-size) heterogeneity located at relatively shallow depth. The preferred origin of this heterogeneity is the Jurassic delamination of subcontinental lithosphere, which occurred during rifting and opening of the North Atlantic. The primitive helium ratios were also observed on the Mid Atlantic ridge at 38.5°N, reflecting plume–ridge interaction, whereas radiogenic ratios (>100,000) were observed at latitude higher than 40°N and may reflect the influence of the São Miguel component at the ridge.</description><identifier>ISSN: 0012-821X</identifier><identifier>EISSN: 1385-013X</identifier><identifier>DOI: 10.1016/S0012-821X(99)00071-0</identifier><language>eng</language><publisher>Elsevier B.V</publisher><subject>Azores ; Earth Sciences ; Geochemistry ; helium ; isotope ratios ; lead ; magmas ; mixing ; Sciences of the Universe ; Volcanology</subject><ispartof>Earth and planetary science letters, 1999-05, Vol.169 (1), p.189-205</ispartof><rights>1999 Elsevier Science B.V.</rights><rights>Distributed under a Creative Commons Attribution 4.0 International License</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-a461t-542054da2d5e07fb8f9e7c5625b4224038589dbefa80e2b4762bbaedf4bb4e723</citedby><cites>FETCH-LOGICAL-a461t-542054da2d5e07fb8f9e7c5625b4224038589dbefa80e2b4762bbaedf4bb4e723</cites><orcidid>0000-0001-5845-4660</orcidid></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktohtml>$$Uhttps://dx.doi.org/10.1016/S0012-821X(99)00071-0$$EHTML$$P50$$Gelsevier$$H</linktohtml><link.rule.ids>230,314,780,784,885,3550,27924,27925,45995</link.rule.ids><backlink>$$Uhttps://uca.hal.science/hal-01902219$$DView record in HAL$$Hfree_for_read</backlink></links><search><creatorcontrib>Moreira, Manuel</creatorcontrib><creatorcontrib>Doucelance, Régis</creatorcontrib><creatorcontrib>Kurz, Mark D.</creatorcontrib><creatorcontrib>Dupré, Bernard</creatorcontrib><creatorcontrib>Allègre, Claude Jean</creatorcontrib><title>Helium and lead isotope geochemistry of the Azores Archipelago</title><title>Earth and planetary science letters</title><description>New helium and lead isotopic data for basalts from the Azores archipelago (North Atlantic) show that the Azores have
4He/
3He ratios both higher and lower than MORB values. Good covariations of helium and lead isotopes are observed at the scale of the archipelago, and suggest the coexistence of two mantle components in the Azores which are identified by data from São Miguel and Terceira. The eastern part of São Miguel island displays radiogenic helium (
4He/
3He > 140,000,
R/
R
a<5.1) and lead (20.00, 15.75 and 40.33 for
206Pb/
204Pb,
207Pb/
204Pb and
208Pb/
204Pb). The
207Pb/
204Pb and
208Pb/
204Pb ratios for São Miguel are unusually radiogenic for oceanic basalts. Terceira basalts contain relatively unradiogenic/primitive
4He/
3He ratios, with a minimum value of 64,000 (
R/
R
a=11.3), and relatively high lead isotopic ratios (
206Pb/
204Pb = 20.02,
207Pb/
204Pb = 15.64 and
208Pb/
204Pb = 39.35). We propose that the Terceira source has a composition produced by a mixing between recycled oceanic crust (high
206Pb/
204Pb) and entrained lower mantle (high
3He) material. The São Miguel island isotopic signature may be due to sampling of local (km-size) heterogeneity located at relatively shallow depth. The preferred origin of this heterogeneity is the Jurassic delamination of subcontinental lithosphere, which occurred during rifting and opening of the North Atlantic. The primitive helium ratios were also observed on the Mid Atlantic ridge at 38.5°N, reflecting plume–ridge interaction, whereas radiogenic ratios (>100,000) were observed at latitude higher than 40°N and may reflect the influence of the São Miguel component at the ridge.</description><subject>Azores</subject><subject>Earth Sciences</subject><subject>Geochemistry</subject><subject>helium</subject><subject>isotope ratios</subject><subject>lead</subject><subject>magmas</subject><subject>mixing</subject><subject>Sciences of the Universe</subject><subject>Volcanology</subject><issn>0012-821X</issn><issn>1385-013X</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>1999</creationdate><recordtype>article</recordtype><recordid>eNqFkE1LAzEQhoMoWKs_QdiT2MPqJM1-5KKUolYoeFCht5BkZ7uRbbMm20L99W670qungeF5X2YeQq4p3FGg6f07AGVxzujiVogRAGQ0hhMyoOM8iYGOF6dkcETOyUUIXx2UJqkYkIcZ1nazitS6iGpURWSDa12D0RKdqXBlQ-t3kSujtsJo8uM8hmjiTWUbrNXSXZKzUtUBr_7mkHw-P31MZ_H87eV1OpnHiqe0jRPOIOGFYkWCkJU6LwVmJklZojljHLpDc1FoLFUOyDTPUqa1wqLkWnPM2HhIRn1vpWrZeLtSfiedsnI2mcv9DqgAxqjY0o696dnGu-8NhlZ2Xxisa7VGtwmS5sC4yLIOTHrQeBeCx_LYTEHuzcqDWbnXJoWQB7MSutxjn8Pu461FL4OxuDZYWI-mlYWz_zT8AvwQf2s</recordid><startdate>19990501</startdate><enddate>19990501</enddate><creator>Moreira, Manuel</creator><creator>Doucelance, Régis</creator><creator>Kurz, Mark D.</creator><creator>Dupré, Bernard</creator><creator>Allègre, Claude Jean</creator><general>Elsevier B.V</general><general>Elsevier</general><scope>AAYXX</scope><scope>CITATION</scope><scope>7TN</scope><scope>F1W</scope><scope>H96</scope><scope>L.G</scope><scope>1XC</scope><orcidid>https://orcid.org/0000-0001-5845-4660</orcidid></search><sort><creationdate>19990501</creationdate><title>Helium and lead isotope geochemistry of the Azores Archipelago</title><author>Moreira, Manuel ; Doucelance, Régis ; Kurz, Mark D. ; Dupré, Bernard ; Allègre, Claude Jean</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-a461t-542054da2d5e07fb8f9e7c5625b4224038589dbefa80e2b4762bbaedf4bb4e723</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>1999</creationdate><topic>Azores</topic><topic>Earth Sciences</topic><topic>Geochemistry</topic><topic>helium</topic><topic>isotope ratios</topic><topic>lead</topic><topic>magmas</topic><topic>mixing</topic><topic>Sciences of the Universe</topic><topic>Volcanology</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Moreira, Manuel</creatorcontrib><creatorcontrib>Doucelance, Régis</creatorcontrib><creatorcontrib>Kurz, Mark D.</creatorcontrib><creatorcontrib>Dupré, Bernard</creatorcontrib><creatorcontrib>Allègre, Claude Jean</creatorcontrib><collection>CrossRef</collection><collection>Oceanic Abstracts</collection><collection>ASFA: Aquatic Sciences and Fisheries Abstracts</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) 2: Ocean Technology, Policy & Non-Living Resources</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) Professional</collection><collection>Hyper Article en Ligne (HAL)</collection><jtitle>Earth and planetary science letters</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Moreira, Manuel</au><au>Doucelance, Régis</au><au>Kurz, Mark D.</au><au>Dupré, Bernard</au><au>Allègre, Claude Jean</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Helium and lead isotope geochemistry of the Azores Archipelago</atitle><jtitle>Earth and planetary science letters</jtitle><date>1999-05-01</date><risdate>1999</risdate><volume>169</volume><issue>1</issue><spage>189</spage><epage>205</epage><pages>189-205</pages><issn>0012-821X</issn><eissn>1385-013X</eissn><abstract>New helium and lead isotopic data for basalts from the Azores archipelago (North Atlantic) show that the Azores have
4He/
3He ratios both higher and lower than MORB values. Good covariations of helium and lead isotopes are observed at the scale of the archipelago, and suggest the coexistence of two mantle components in the Azores which are identified by data from São Miguel and Terceira. The eastern part of São Miguel island displays radiogenic helium (
4He/
3He > 140,000,
R/
R
a<5.1) and lead (20.00, 15.75 and 40.33 for
206Pb/
204Pb,
207Pb/
204Pb and
208Pb/
204Pb). The
207Pb/
204Pb and
208Pb/
204Pb ratios for São Miguel are unusually radiogenic for oceanic basalts. Terceira basalts contain relatively unradiogenic/primitive
4He/
3He ratios, with a minimum value of 64,000 (
R/
R
a=11.3), and relatively high lead isotopic ratios (
206Pb/
204Pb = 20.02,
207Pb/
204Pb = 15.64 and
208Pb/
204Pb = 39.35). We propose that the Terceira source has a composition produced by a mixing between recycled oceanic crust (high
206Pb/
204Pb) and entrained lower mantle (high
3He) material. The São Miguel island isotopic signature may be due to sampling of local (km-size) heterogeneity located at relatively shallow depth. The preferred origin of this heterogeneity is the Jurassic delamination of subcontinental lithosphere, which occurred during rifting and opening of the North Atlantic. The primitive helium ratios were also observed on the Mid Atlantic ridge at 38.5°N, reflecting plume–ridge interaction, whereas radiogenic ratios (>100,000) were observed at latitude higher than 40°N and may reflect the influence of the São Miguel component at the ridge.</abstract><pub>Elsevier B.V</pub><doi>10.1016/S0012-821X(99)00071-0</doi><tpages>17</tpages><orcidid>https://orcid.org/0000-0001-5845-4660</orcidid></addata></record> |
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| ispartof | Earth and planetary science letters, 1999-05, Vol.169 (1), p.189-205 |
| issn | 0012-821X 1385-013X |
| language | eng |
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| source | Access via ScienceDirect (Elsevier) |
| subjects | Azores Earth Sciences Geochemistry helium isotope ratios lead magmas mixing Sciences of the Universe Volcanology |
| title | Helium and lead isotope geochemistry of the Azores Archipelago |
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