Isotope and trace element insights into heterogeneity of subridge mantle
Abstract Geochemical data for abyssal peridotites are used to determine the relationship to mid‐ocean ridge basalts from several locations at ridge segments on the SW Indian Ridge (SWIR), the Mid‐Cayman‐Rise (MCR), and the Mid‐Atlantic Ridge (MAR). Based on chemical and petrological criteria peridot...
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Wiley
2014-06-01
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| Series: | Geochemistry, Geophysics, Geosystems |
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| Online Access: | https://doi.org/10.1002/2014GC005314 |
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| author | Soumen Mallick Henry J. B. Dick Afi Sachi‐Kocher Vincent J. M. Salters |
| author_facet | Soumen Mallick Henry J. B. Dick Afi Sachi‐Kocher Vincent J. M. Salters |
| author_sort | Soumen Mallick |
| collection | DOAJ |
| description | Abstract Geochemical data for abyssal peridotites are used to determine the relationship to mid‐ocean ridge basalts from several locations at ridge segments on the SW Indian Ridge (SWIR), the Mid‐Cayman‐Rise (MCR), and the Mid‐Atlantic Ridge (MAR). Based on chemical and petrological criteria peridotites are categorized as being either dominantly impregnated with melt or being residual after recent melting. Those that are considered impregnated with melt also have isotopic compositions similar to the basalts indicating impregnation by an aggregate MORB melt. A SWIR and MCR residual peridotite Nd‐isotopic compositions partly overlap the Nd‐isotopic compositions of the basalts but extend to more radiogenic compositions. The differences between peridotite and basalt Nd‐isotopic compositions can be explained by incorporating a low‐solidus component with enriched isotopic signature in the subridge mantle: a component that is preferentially sampled by the basalts. At the MAR, peridotites and associated basalts have overlapping Nd‐isotopic compositions, suggesting a more homogeneous MORB mantle. The combined chemistry and petrography indicates a complex history with several depletion and enrichment events. The MCR data indicate that a low‐solidus component can be a ubiquitous component of the asthenosphere. Residual abyssal peridotites from limited geographic areas also show significant chemical variations that could be associated with initial mantle heterogeneities related to events predating the ridge‐melting event. Sm‐Nd model ages for possible earlier depletion events suggest these could be as old as 2.4 Ga. |
| format | Article |
| id | doaj-art-65ebb029c46d4b91ba85e4ff4c3244ab |
| institution | Kabale University |
| issn | 1525-2027 |
| language | English |
| publishDate | 2014-06-01 |
| publisher | Wiley |
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| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj-art-65ebb029c46d4b91ba85e4ff4c3244ab2025-08-20T03:32:04ZengWileyGeochemistry, Geophysics, Geosystems1525-20272014-06-011562438245310.1002/2014GC005314Isotope and trace element insights into heterogeneity of subridge mantleSoumen Mallick0Henry J. B. Dick1Afi Sachi‐Kocher2Vincent J. M. Salters3National High Magnetic Field Laboratory Department of Earth Ocean and Atmospheric ScienceFlorida State UniversityTallahassee Florida USAWoods Hole Oceanographic Institution Department of Marine Geology and GeophysicsWoods Hole Massachusetts USANational High Magnetic Field Laboratory Department of Earth Ocean and Atmospheric ScienceFlorida State UniversityTallahassee Florida USANational High Magnetic Field Laboratory Department of Earth Ocean and Atmospheric ScienceFlorida State UniversityTallahassee Florida USAAbstract Geochemical data for abyssal peridotites are used to determine the relationship to mid‐ocean ridge basalts from several locations at ridge segments on the SW Indian Ridge (SWIR), the Mid‐Cayman‐Rise (MCR), and the Mid‐Atlantic Ridge (MAR). Based on chemical and petrological criteria peridotites are categorized as being either dominantly impregnated with melt or being residual after recent melting. Those that are considered impregnated with melt also have isotopic compositions similar to the basalts indicating impregnation by an aggregate MORB melt. A SWIR and MCR residual peridotite Nd‐isotopic compositions partly overlap the Nd‐isotopic compositions of the basalts but extend to more radiogenic compositions. The differences between peridotite and basalt Nd‐isotopic compositions can be explained by incorporating a low‐solidus component with enriched isotopic signature in the subridge mantle: a component that is preferentially sampled by the basalts. At the MAR, peridotites and associated basalts have overlapping Nd‐isotopic compositions, suggesting a more homogeneous MORB mantle. The combined chemistry and petrography indicates a complex history with several depletion and enrichment events. The MCR data indicate that a low‐solidus component can be a ubiquitous component of the asthenosphere. Residual abyssal peridotites from limited geographic areas also show significant chemical variations that could be associated with initial mantle heterogeneities related to events predating the ridge‐melting event. Sm‐Nd model ages for possible earlier depletion events suggest these could be as old as 2.4 Ga.https://doi.org/10.1002/2014GC005314abyssal peridotitesmid‐ocean ridge basaltsrefertilizationmeltingdepletion eventlow solidus |
| spellingShingle | Soumen Mallick Henry J. B. Dick Afi Sachi‐Kocher Vincent J. M. Salters Isotope and trace element insights into heterogeneity of subridge mantle Geochemistry, Geophysics, Geosystems abyssal peridotites mid‐ocean ridge basalts refertilization melting depletion event low solidus |
| title | Isotope and trace element insights into heterogeneity of subridge mantle |
| title_full | Isotope and trace element insights into heterogeneity of subridge mantle |
| title_fullStr | Isotope and trace element insights into heterogeneity of subridge mantle |
| title_full_unstemmed | Isotope and trace element insights into heterogeneity of subridge mantle |
| title_short | Isotope and trace element insights into heterogeneity of subridge mantle |
| title_sort | isotope and trace element insights into heterogeneity of subridge mantle |
| topic | abyssal peridotites mid‐ocean ridge basalts refertilization melting depletion event low solidus |
| url | https://doi.org/10.1002/2014GC005314 |
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