Abstract
Mantle plumes contain heterogenous chemical components and sample variable depths of the mantle, enabling glimpses into the compositional structure of Earth's interior. In this study, we evaluated ocean island basalts (OIB) from nine plume locations to provide a global and systematic assessment of the relationship between fO2 and He-Sr-Nd-Pb-W-Os isotopic compositions. Ocean island basalts from the Pacific (Austral Islands, Hawaii, Mangaia, Samoa, Pitcairn), Atlantic (Azores, Canary Islands, St. Helena), and Indian Oceans (La Réunion) reveal that fO2 in OIB is heterogeneous both within and among hotspots. Taken together with previous studies, global OIB have elevated and heterogenous fO2 (average = +0.5 ∆FMQ; 2SD = 1.5) relative to prior estimates of global mid-ocean ridge basalts (MORB; average = −0.1 ∆FMQ; 2SD = 0.6), though many individual OIB overlap MORB. Specific mantle components, such as HIMU and enriched mantle 2 (EM2), defined by radiogenic Pb and Sr isotopic compositions compared to other OIB, respectively, have distinctly high fO2 based on statistical analysis. Elevated fO2 in OIB samples of these components is associated with higher whole-rock CaO/Al2O3 and olivine CaO content, which may be linked to recycled carbonated oceanic crust. EM1-type and geochemically depleted OIB are generally not as oxidized, possibly due to limited oxidizing potential of the recycled material in the enriched mantle 1 (EM1) component (e.g., sediment) or lack of recycled materials in geochemically depleted OIB. Despite systematic offset of the fO2 among EM1-, EM2-, and HIMU-type OIB, geochemical indices of lithospheric recycling, such as Sr-Nd-Pb-Os isotopic systems, generally do not correlate with fO2.
Recommended Citation
L. N. Willhite and R. Arevalo and P. Piccoli and J. C. Lassiter and D. Rand and M. G. Jackson and J. M. Day and R. W. Nicklas and M. Locmelis and T. J. Ireland and I. S. Puchtel, "Oxygen Fugacity Of Global Ocean Island Basalts," Geochemistry, Geophysics, Geosystems, vol. 25, no. 1, article no. e2023GC011249, Wiley Open Access; American Geophysical Union; Geochemical Society, Jan 2024.
The definitive version is available at https://doi.org/10.1029/2023GC011249
Department(s)
Geosciences and Geological and Petroleum Engineering
Publication Status
Open Access
Keywords and Phrases
crustal recycling; mantle plume; ocean island basalt; oxygen fugacity
International Standard Serial Number (ISSN)
1525-2027
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2024 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
01 Jan 2024
Comments
National Aeronautics and Space Administration, Grant 1944552