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In our study, we plan to focus on this recycling process by looking at one particular subduction zone - the margin of Central America - in some detail. Central America was chosen because of its abundant volcanic activity and well-characterised sediment record on the down-going (Cocos) plate. In this way, we have a good idea of the amount and composition of material being returned to the mantle (the input parameter) for comparison with the output parameter — what is being transferred from the mantle back to the surface via magmatic and volcanic activity. We are interested in finding out if a balance exists between input and output for various volatile species (carbon dioxide in particular) or whether there is a net sink of volatiles at subduction zones with some fraction of the volatile inventory transferred to the deeper mantle — for possible later re-emergence via mid-ocean ridge or plume-related volcanism.

To try and answer these questions about volatile mass balances at subduction zones, we plan to sample volcanic gases and lavas from along the entire Central American margin from Guatemala in the northwest to Costa Rica in the southeast. An important aspect of the study will be to characterize how changes along the Central American subduction zone (e.g. differences in age and type of sediment being subducted, thickness of overlying crust through which the magmas are erupted) influence the output parameter. We envisage that the whole project will involve 3-4 visits to Central America, with the present trip, to Costa Rica, representing the first stage of this exciting scientific endeavor.

A Collaborative Study>>