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Sulfide mantle source heterogeneity recorded in basaltic lavas from the Azores

2020-01-01
Waters, Christopher L.
Day, James M. D.
Watanabe, Shizuko
Sayıt, Kaan
Zanon, Vittorio
Olson, Kristina M.
Hanan, Barry B.
Widom, Elisabeth
New highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) abundance and Os isotopic compositions, along with major- and trace-element abundance and Sr-Nd-Hf-Pb isotope data are reported for high-MgO (>8-17 wt.%) lavas from the islands of Sao Miguel, Terceira, Pico and Faial in the Azores archipelago. The lavas span the range of Sr-Nd-Hf-Pb isotope and trace-element abundance variability reported previously for the islands. Pico and Faial lavas preserve distinct absolute and relative HSE abundances and Os-187/Os-188 (Sigma(HSE) = 2 +/- 2 ng g(-1); 2SD; Os-187/Os-188 in lavas with > 50 pg g(-1) Os = 0.1255 +/- 31; 2SD) compared with Sao Miguel and Terceira lavas (Sigma(HSE) = 5 +/- 3 ng g(-1) ; Os-187/Os-188(50pg) = 0.1284 +/- 48). Although HSE abundance variations in volcanic rocks from individual Azorean islands can be explained by sulfide crystallization, those between Pico and Faial and Sao Miguel and Terceira can only reasonably be attributed to partial melting of distinct mantle sources.