Boron recycling in the mantle: Evidence from a global comparison of ocean island basalts
نویسندگان
چکیده
Radiogenic and noble gas isotopes have been integral for demonstrating the existence, source, age of (geo) chemical reservoirs in mantle, yet, volatile element composition Earth’s interior remains poorly characterized. Boron potential to constrain processes that generate distinct mantle reservoirs, as they fractionate strongly at surface Earth during subduction but are little perturbed high-temperature processes, so can inform our understanding cycling. Here, we present largest, internally consistent, high-precision B isotope dataset from ocean island basalt (OIB) glasses olivine-hosted melt inclusions measured by Secondary Ion Mass Spectrometry (SIMS) date, including new data derived Pitcairn Islands, Tristan da Cunha, St. Helena, Ascension Island, MacDonald (Ra) Seamount, Fogo (Cape Verde Islands) addition previously published La Réunion, Palma (Canary Islands), Iceland, Hawai’i. This allows a comparison basalts contain heterogeneous recycled components (e.g., those with primordial Réunion) their sources. We focus on basaltic glass (>6 wt% MgO) least affected shallow differentiation assimilation processes. find OIB show limited spread average δ11B (−5.9 ± 3.0‰ −10.8 0.7‰), which is smaller compared previous studies. These generally overlap mid-ocean ridge (MORB; −7.1 0.9‰) display lighter values when mafic arc magmas (∼−9 +20‰). Importantly, some trace enriched endmembers lower B/P B/Zr, indicative source concentrations relative mantle. suggests deeper becoming increasingly B-depleted over time because boron effectively stripped lithologies slab dehydration. In addition, results highlight decoupling radiogenic (Sr, Pb) providing perspective recycling.
منابع مشابه
Major element chemistry of ocean island basalts — Conditions of mantle melting and heterogeneity of mantle source
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ژورنال
عنوان ژورنال: Geochimica et Cosmochimica Acta
سال: 2021
ISSN: ['1872-9533', '0016-7037']
DOI: https://doi.org/10.1016/j.gca.2021.03.017