Geochemistry of subducted volcaniclastic sediments from Mariana arc magmas


The phase relations of natural volcaniclastic sediments from the west Pacific Ocean were investigated experimentally at conditions of 3-6 GPa and 800-900 °C with 10 wt.% added H2O (in addition to ~ 10 wt.% structurally-bound H2O) to induce hydrous melting. Volcaniclastic sediments are shown to produce a sub-solidus assemblage of garnet, clinopyroxene, biotite, quartz/coesite and the accessory phases rutile ± Fe-Ti oxide ± apatite ± monazite ± zircon. Hydrous melt appears at temperatures exceeding 800-850 °C, irrespective of pressure. The melt-producing reaction consumes clinopyroxene, biotite and quartz/coesite and produces orthopyroxene. These phase relations differ from those of pelagic clays and K-bearing mid ocean ridge basalts (e.g. altered oceanic crust) that contain phengite, rather than biotite, as a sub-solidus phase. Despite their relatively high melt productivity, the wet solidus for volcaniclastic sediments is found to be higher (825-850 °C) than other marine sediments (700-750 °C) at 3 GPa. This trend is reversed at high-pressure conditions (6 GPa) where the biotite melting reaction occurs at lower temperatures (800-850 °C) than the phengite melting reaction (900-1000 °C).

Metadata Access
Creator Martindale, Marina;Blundy, Jonathan;Skora, Susanne;Elliott, Tim;Avanzinelli, Riccardo;Pickles, Jonathan
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 2016
Rights Creative Commons Attribution 3.0 Unported (CC-BY)
Language English
Resource Type Collection of Datasets
Format application/zip
Discipline Earth System Research
Spatial Coverage (19N-19N,156E-156E)
Temporal Point 1989-12-06T11:59:59Z