The Origin of Felsic Intrusions Within the Mantle Section of the Samail Ophiolite: Geochemical Evidence for Three Distinct Mixing and Fractionation Trends

An isotopically diverse suite of felsic dikes, sills, and plugs (εNd(t) = −7.8 to +7.8) intrude the uppermost mantle lower crust in Samail ophiolite Oman United Arab Emirates (UAE). These features have been interpreted represent amphibolite metasediment melts from an underthrust sheet oceanic lithosphere. As such, intrusions provide a record melting sediment at depth, with implications for mass transfer down-going plate young, hot subduction settings. Several studies used geochemical data constrain magmatic sources dikes; here we build on this previous work using integrated whole rock major element, trace element Nd isotopic more geographically extensive dikes. New existing suggest preserved within peridotites portion were generated by three distinct mixing fractionation trends: (1) three-component between melt, melt component; (2) two component melts, little contribution; (3) fractional crystallization depleted, derived magmas, likely related V2 volcanic series. Combined pseudosection modeling that occurred P ≤ 1.4 GPa (∼40–45 km) T ≥ 700–750°C. Felsic section UAE, including garnet-andalusite-cordierite leucogranites, follow similar trends, but crystallized ∼0.9–4.0 Ma after intrusions.