The fate of water at subduction zones
Examining the role of the dragged-down forearc mantle using mass balance calculations and 2D fluid dynamic equations.
Volatiles (CO2, H2O, S, Cl) are key features of the Earth and they are efficiently cycled at subduction zones. They modulate volcanic hazards, composition of the continental crust through time, long-term control of the climate, and Earth habitability. They have also affected the long-term evolution of our planet by facilitating plate tectonics and mantle convection. Water is one of the most important of the volatile species on Earth as it largely contributes to life and oceans.
Here, we seek to further examine the extent to which the slab dehydrates beneath the fore-arc mantle and whether the water captured by the arc magmas derive solely from slab dehydration. If the slab dehydrates efficiently to serpentinize the cold fore-arc mantle wedge, we must consider the possibility that s dragging downward the serpentinized fore-arc mantle may contribute to the generation of arc magmas. Here, we combine geochemistry and simple fluid-dynamic equations to place new constraints on the budget and the origin of water delivered in subduction zone magmas.
Ribeiro J.M., Lee C.T.A. (2017) An imbalance in the deep water cycle at subduction zones: Recognizing the importance of the fore-arc mantle, Earth and Planetary Science Letters.
Ribeiro J.M., Stern R.J., Kelley K.A., Shaw A., Martinez F., Ohara Y. (2015) Composition of the slab-derived fluids released beneath the Mariana forearc: evidence for shallow dehydration of the subducting plate.Earth and Planetary Science Letters, doi: 10.1016/j.epsl.2015.02.018.