Redox Heterogeneity in Mid-Ocean Ridge Basalts as a Function of Mantle Source.

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Bibliographic Details
Title: Redox Heterogeneity in Mid-Ocean Ridge Basalts as a Function of Mantle Source.
Authors: Cottrell, Elizabeth, Kelley, Katherine A.
Source: Science (pre-March 2025). 6/14/2013, Vol. 340 Issue 6138, p1314-1317. 4p.
Subjects: Geochemistry, Oxidation, Basalt analysis, Magmas, Obsidian, Carbon & the environment, Earth's mantle
Geographic Terms: Mid-Atlantic Ridge
Abstract: The oxidation state of Earth's upper mantle both influences and records mantle evolution, but systematic fine-scale variations in upper mantle oxidation state have not previously been recognized in mantle-derived lavas from mid-ocean ridges. Through a global survey of mid-ocean ridge basalt glasses, we show that mantle oxidation state varies systematically as a function of mantle source composition. Negative correlations between Fe3+/σFe ratios and indices of mantle enrichment--such as 87Sr/86Sr, 208Pb/204Pb, Ba/La, and Nb/Zr ratios--reveal that enriched mantle is more reduced than depleted mantle. Because carbon may act to simultaneously reduce iron and generate melts that share geochemical traits with our reduced samples, we propose that carbon creates magmas at ridges that are reduced and enriched. [ABSTRACT FROM AUTHOR]
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Database: Psychology and Behavioral Sciences Collection
Description
Abstract:The oxidation state of Earth's upper mantle both influences and records mantle evolution, but systematic fine-scale variations in upper mantle oxidation state have not previously been recognized in mantle-derived lavas from mid-ocean ridges. Through a global survey of mid-ocean ridge basalt glasses, we show that mantle oxidation state varies systematically as a function of mantle source composition. Negative correlations between Fe3+/σFe ratios and indices of mantle enrichment--such as 87Sr/86Sr, 208Pb/204Pb, Ba/La, and Nb/Zr ratios--reveal that enriched mantle is more reduced than depleted mantle. Because carbon may act to simultaneously reduce iron and generate melts that share geochemical traits with our reduced samples, we propose that carbon creates magmas at ridges that are reduced and enriched. [ABSTRACT FROM AUTHOR]
ISSN:00368075
DOI:10.1126/science.1233299