Our studies in Costa Rica are crucial to understanding
not only how volcanoes work including how volatiles influence
the eruption process, but also how certain elements are cycled via
volcanic pathways between the Earths underlying mantle and
surface reservoirs such as the crust, hydrosphere and atmosphere.
The down-going plate carries with it marine sediments: exactly how
much of this material actually makes it down into the Earths
mantle and back out via volcanism is very poorly constrained. By
looking at the type and amounts of sediments being subducted, and
comparing them chemically and isotopically to the gases which are
fluxing out of the adjacent volcanoes, we hope to be able to quantify
the percentage of each volatile species that makes it around the
One species of particular interest is carbon
dioxide, well-known as a greenhouse gas contributing to global warming.
Knowledge of how much CO2 is lost via volcanoes not only
allows us to establish a baseline for natural fluxes of CO2
to the atmosphere but also provides constraints on the inventory
of carbon in the Earths largest reservoir the mantle.
This CO2 flux, however, is not an easy parameter to quantify
but one useful approach is to couple CO2 measurements
to the rare isotope of helium (helium-3) whose flux from the mantle
to the atmosphere is well known. Therefore, we will be using our
measurements of the CO2/3He ratio at the various
volcanoes in Costa Rica to derive CO2 flux estimates
for the region.
- Geochemical Tracers>>