Quenching of basaltic melts by volatile exsolution

Abstract Normally, volatiles in silicate melts are ephemeral components that escape as gases when the melt reaches fluid saturation. When saturation occurs at elevated pressure, magmatic fluids may have large amounts of oxide solute dissolved, less volatile, and resemble viscous gels. In Cyprus we rare case solutes a coexist with H 2 O saturated basaltic to boninitic glasses. Quenching was induced by segregation. exsolved, liquidus temperature raised were left supercooled, while system remained ± constant. rates deduced from morphologies compositions quench crystals high. We analyzed coexisting glasses for major trace elements. The mobile elements (Rb, K, Pb, Sr) enriched both solutes. Both endmembers (melt fluid) common parentage originated within hydrous mantle source. 2.5 0.25 wt.% record residual contents after exsolution completed. Water correspond an partial pressure (pH O) 65 10 MPa emplacement depth on seafloor 6500 1000 m, provided equilibrium reached between pH imposed seawater column. Following exsolution, degree supercooling ∆T relative dry MgO-in-melt – °C. cooling rate ∆T/t time crystallization dendritic clinopyroxene can be semi-quantified distribution Al 3 metastable dendrites melt, least 50 °C h −1 . Toward end article speculate if other cases exist where quenching triggered exsolution. A possible example spinifex textures deep inside komatiite flows conductive did not exceed 0.3 1 Our proposition assumes many spinifex-textured komatiites hydrous, they contained quantities sufficient reach formed result supersaturation loss.