New isotopic data for Mid-Atlantic Ridge basalts from the Arkhangelsk-Sierra Leone fracture zone (central Atlantic).
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| Title: | New isotopic data for Mid-Atlantic Ridge basalts from the Arkhangelsk-Sierra Leone fracture zone (central Atlantic). |
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| Authors: | Skolotnev, S.1 sg_skol@mail.ru |
| Source: | Doklady Earth Sciences. Nov2014, Vol. 459 Issue 1, p1429-1435. 7p. |
| Subjects: | Isotopic fractionation, Basalt analysis, Fault zones, Igneous rocks |
| Geographic Terms: | Mid-Atlantic Ridge, Atlantic Coast (Sierra Leone) |
| Abstract: | This study presents Sr, Nd, and Pb isotopic data for basalts collected from the MAR axis between the Arkhangelsk transform fault and 5° N. The isotopic data for basalts from the MAR segment between the Arkhangelsk and Vernadsky faults indicate the presence of N-MORB depleted tholeiites, which are similar to some basalts from the MAR segment between the Cape Verde and Marathon faults, at the location of the 14° N geochemical anomaly. Broad positive along-axis gradients in isotopic values (and negative for Nd/Nd) are observed from south to north, superimposed by isotopic variations in the 9.6° N anomalous basalts. A north-south increase in (La/Sm) suggests a smaller degree of partial melting. The range of isotopic variations in basalts south of the Bogdanov fault is similar to that of basalts recovered at the more southerly 1.7° N anomaly. P-MORB compositions with a large proportion of the HIMU-like component are widely distributed in the vicinity of the 5.4° N rise. The isotopic ratios decrease gradually (with increasing Nd/Nd) farther to the north toward the Bogdanov transform fault. A similar trend is observed for (La/Sm). Therefore, the basalts recovered to the south and north of Bogdanov fault have different sources of radiogenic isotope enrichment: 5.4° N and 9.6° N rises. Basalts recovered to the north of the Vernadsky transform fault have higher Nd/Nd and lower Pb/Pb at similar Sr/Sr ratios. We conclude that the localized manifestations of enriched basalts with isotopic characteristics close to the HIMU-like plume-derived component, including the 14° N and 1.7° N geochemical anomalies, may have been formed by microplumes entrained at the base of the upper mantle by asthenospheric mantle flows arranged into a system of cylindrical convective cells, 450-500 km in diameter. Northward of the Bogdanov transform, the upper mantle is contaminated with lower continental crust material, which was entrained during tectonic erosion of the lithosphere beneath the equatorial segment of Gondwanaland during its late stage opening. [ABSTRACT FROM AUTHOR] |
| Copyright of Doklady Earth Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Items | – Name: Title Label: Title Group: Ti Data: New isotopic data for Mid-Atlantic Ridge basalts from the Arkhangelsk-Sierra Leone fracture zone (central Atlantic). – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Skolotnev%2C+S%2E%22">Skolotnev, S.</searchLink><relatesTo>1</relatesTo><i> sg_skol@mail.ru</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Doklady+Earth+Sciences%22">Doklady Earth Sciences</searchLink>. Nov2014, Vol. 459 Issue 1, p1429-1435. 7p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Isotopic+fractionation%22">Isotopic fractionation</searchLink><br /><searchLink fieldCode="DE" term="%22Basalt+analysis%22">Basalt analysis</searchLink><br /><searchLink fieldCode="DE" term="%22Fault+zones%22">Fault zones</searchLink><br /><searchLink fieldCode="DE" term="%22Igneous+rocks%22">Igneous rocks</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Mid-Atlantic+Ridge%22">Mid-Atlantic Ridge</searchLink><br /><searchLink fieldCode="DE" term="%22Atlantic+Coast+%28Sierra+Leone%29%22">Atlantic Coast (Sierra Leone)</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: This study presents Sr, Nd, and Pb isotopic data for basalts collected from the MAR axis between the Arkhangelsk transform fault and 5° N. The isotopic data for basalts from the MAR segment between the Arkhangelsk and Vernadsky faults indicate the presence of N-MORB depleted tholeiites, which are similar to some basalts from the MAR segment between the Cape Verde and Marathon faults, at the location of the 14° N geochemical anomaly. Broad positive along-axis gradients in isotopic values (and negative for Nd/Nd) are observed from south to north, superimposed by isotopic variations in the 9.6° N anomalous basalts. A north-south increase in (La/Sm) suggests a smaller degree of partial melting. The range of isotopic variations in basalts south of the Bogdanov fault is similar to that of basalts recovered at the more southerly 1.7° N anomaly. P-MORB compositions with a large proportion of the HIMU-like component are widely distributed in the vicinity of the 5.4° N rise. The isotopic ratios decrease gradually (with increasing Nd/Nd) farther to the north toward the Bogdanov transform fault. A similar trend is observed for (La/Sm). Therefore, the basalts recovered to the south and north of Bogdanov fault have different sources of radiogenic isotope enrichment: 5.4° N and 9.6° N rises. Basalts recovered to the north of the Vernadsky transform fault have higher Nd/Nd and lower Pb/Pb at similar Sr/Sr ratios. We conclude that the localized manifestations of enriched basalts with isotopic characteristics close to the HIMU-like plume-derived component, including the 14° N and 1.7° N geochemical anomalies, may have been formed by microplumes entrained at the base of the upper mantle by asthenospheric mantle flows arranged into a system of cylindrical convective cells, 450-500 km in diameter. Northward of the Bogdanov transform, the upper mantle is contaminated with lower continental crust material, which was entrained during tectonic erosion of the lithosphere beneath the equatorial segment of Gondwanaland during its late stage opening. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Doklady Earth Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1134/S1028334X14100110 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 7 StartPage: 1429 Subjects: – SubjectFull: Isotopic fractionation Type: general – SubjectFull: Basalt analysis Type: general – SubjectFull: Fault zones Type: general – SubjectFull: Igneous rocks Type: general – SubjectFull: Mid-Atlantic Ridge Type: general – SubjectFull: Atlantic Coast (Sierra Leone) Type: general Titles: – TitleFull: New isotopic data for Mid-Atlantic Ridge basalts from the Arkhangelsk-Sierra Leone fracture zone (central Atlantic). Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Skolotnev, S. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 11 Text: Nov2014 Type: published Y: 2014 Identifiers: – Type: issn-print Value: 1028334X Numbering: – Type: volume Value: 459 – Type: issue Value: 1 Titles: – TitleFull: Doklady Earth Sciences Type: main |
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