Ultrahigh-precision noble gas isotope analyses reveal pervasive subsurface fractionation in hydrothermal systems

• DOI: 10.1126/sciadv.adg2566
• Publication Date: 2023-04-14T17:58:17Z
• Authors: David V. Bekaert; Peter H. Barry; Michael W. Broadley; David J. Byrne; Bernard Marty; Carlos J. Ramírez; J. Maarten de Moor; Alejandro Rodriguez; Michael R. Hudak; Adam V. Subhas; Saemundur A. Hall...; Gerdhard L. Jessen; Jenny M. Blamey; Andri Stefánsson; Antonio Caracausi; Karen G. Lloyd; Donato Giovannelli; Alan M. Seltzer
• Keywords: Noble gas; Isotopic signature; Krypton; Volatiles; Radiogenic nuclide; Subaerial

Mantle-derived noble gases in volcanic are powerful tracers of terrestrial volatile evolution, as they contain mixtures both primordial (from Earth’s accretion) and secondary (e.g., radiogenic) isotope signals that characterize the composition deep Earth. However, emitted through subaerial hydrothermal systems also contributions from shallow reservoirs (groundwater, crust, atmosphere). Deconvolving source is critical for robust interpretations mantle-derived signals. Here, we use a novel dynamic mass spectrometry technique to measure argon, krypton, xenon isotopes gas with ultrahigh precision. Data Iceland, Germany, United States (Yellowstone, Salton Sea), Costa Rica, Chile show subsurface fractionation within globally pervasive previously unrecognized process causing substantial nonradiogenic Ar-Kr-Xe variations. Quantitatively accounting this vital accurately interpreting nitrogen) signals, profound implications our understanding evolution.