Helium, inorganic and organic carbon isotopes of fluids and gases across the Costa Rica convergent margin

Abstract

In 2017, fluid and gas samples were collected across the Costa Rican Arc. He and Ne isotopes, C isotopes as well as total organic and inorganic carbon concentrations were measured. The samples (n = 24) from 2017 are accompanied by (n = 17) samples collected in 2008, 2010 and 2012. He-isotopes ranged from arc-like (6.8 R _A) to crustal (0.5 R _A). Measured dissolved inorganic carbon (DIC) δ ¹³C _VPDB values varied from 3.55 to −21.57‰, with dissolved organic carbon (DOC) following the trends of DIC. Gas phase CO ₂ only occurs within ~20 km of the arc; δ ¹³C _VPDB values varied from −0.84 to −5.23‰. Onsite, pH, conductivity, temperature and dissolved oxygen (DO) were measured; pH ranged from 0.9–10.0, conductivity from 200–91,900 μS/cm, temperatures from 23–89 °C and DO from 2–84%. Data were used to develop a model which suggests that ~91 ± 4.0% of carbon released from the slab/mantle beneath the Costa Rican forearc is sequestered within the crust by calcite deposition with an additional 3.3 ± 1.3% incorporated into autotrophic biomass.

Abstract

Measurement(s)	temperature of air • pH • Total Organic Carbon • carbon-13 atom • dissolved inorganic carbon content • dissolved organic carbon content • carbon dioxide • helium-3 atom • helium-4 atom • methane
Technology Type(s)	Temperature Probe Device • pH sensor • mass spectrometer
Factor Type(s)	time • location where data was collected
Sample Characteristic - Environment	volcanic arc • fumarole • hot spring • seep
Sample Characteristic - Location	Costa Rica

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.10293350