Barium isotope evidence of a fluid-metasomatized mantle component in the source of Azores OIB

This study presents Ba isotope compositions of ocean island basalts (OIB) from the Azores Archipelago to investigate origin enriched components within their mantle sources. These samples have large variations in radiogenic Sr-Nd-Pb-Hf compositions, indicating that they tap highly heterogeneous They display two types characteristics. Samples Faial, Pico, São Jorge, and Miguel Islands exhibit homogeneous MORB-like whereas Terceira Island variable isotopes. The δ138/134Ba values range −0.03 +0.24‰, extending significantly higher than those other islands. composition Jorge indicates HIMU/FOZO material plume source has a composition. In contrast, are characterized by heavy which likely inherited subducted altered oceanic crust (AOC) may reflect presence shallower beneath Terceira. As archipelago is located at triple junction far any active subduction zone, signature AOC must be an ancient feature, potentially derived recycled fluid-metasomatized component now present archipelago. negative correlation between 206Pb/204Pb positive Ba/Th among selected mixing shallower, recycled,