Frontiers in Earth Science (Mar 2022)
Effect of Terrigenous Sediment Addition on the Generation of Arc Silicic Magma: Constraints From the Comparative Partial Melting Experiment at 1.5 GPa
Abstract
To assess the effects of sediment addition on the partial melting of subducted oceanic crust and generation of arc silicic magma, a series of comparative partial melting experiments on a garnet plagioamphibolite and a 90 wt% garnet plagioamphibolite + 10 wt% plagioclase slate mixture at 850–1,000°C/1.5 GPa were conducted on a Piston-cylinder apparatus. In the experimental products, partial melt coexists with amphibole + plagioclase + garnet + clinopyroxene at 850–950°C and plagioclase + garnet + clinopyroxene at 1000°C. Compared with pure garnet plagioamphibolite, partial melting of mixture get a higher melting percentage and generates the silicic melt with geochemical characteristics of higher Na2O/K2O and lower Al2O3 in major element and high Rb content in trace element at over 950°C. This result indicates that silicic arc magma may generate from partial melting of metamorphic subducted oceanic crust with sediments thereon, sediment addition contributes to their chemical component and generation dynamic process.
Keywords
