Recycling of nitrogen and light noble gases in the Central American subduction zone: Constraints from 15N15N

How much nitrogen and light noble gases are recycled in modern subduction zones is unclear. Fumaroles act as a means for passive degassing arcs. They receive variable contributions of volatiles from arc magmas, themselves sourced the mantle wedge. The gas compositions reflect extent volatile enrichment sub-arc sources constrain slab dehydration. However, atmospheric components fumaroles unavoidable. For N2, neon argon, challenging to discern slab-derived components. Here, we report 15N15N measurements eight seven bubbling springs, along Central American arc. Our new data coupled with show that air-derived volcanic discharges can easily be underestimated, both using conventional stable isotope or methods. We that, absence data, previously used tracers air (e.g., δ15N, N2/Ar, N2/He, among others) may lead erroneous conclusions regarding origin mixed gases. In contrast, provide quantitative constraints on nature magmatic Most springs heavily dominated by while substantial endmembers. Based fumarole magma beneath central enriched all relative 3He, two three orders magnitude compared MORB source. use obtain source N2/3He, 3He/36Ar 3He/22Ne ratios which then compute Ar Ne fluxes. Using this approach, outgassing fluxes appear match America zone. determine an N2 flux between 4.0×108 1.0×109 mol N2/y, comparable 5.7×108 N2/yr determined previously. similar conclusion 22Ne 36Ar. Overall, zone no longer seem require net transfer Ar, Ne, deep mantle.