Mineralogical and Geochemical Constraints on the Mantle Source Characteristics of Basaltic Lavas from the Central Mariana Trough

The composition of mantle-derived basalts reflects the nature of their mantle source regions, which constrain magma generation and composition. Here we present a new whole rock major and trace elements and phenocryst composition of the basaltic lava in the central Mariana Trough. These data provide insights into the mantle source characteristics affected by subduction components. The rocks range from basalts to basaltic andesites, which have high subduction-mobile element contents ( e.g. , K, U, Th, LREE) related to N-MORB. The calculated temperature and depth of magma generation are about 1300 °C and 30 km, respectively. Although the results above suggest that the addition of hydrous fluid and/or a melt derived from a slab decreases the temperature of mantle partial melting and mildly modifies the composition of a mantle source, the mantle source lithology from which primary magma is generated remains to be peridotite.