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

• Published in: Science Advances
• Main Authors: Bekaert, David V, Barry, Peter H, Broadley, Michael W, Byrne, David J, Marty, Bernard, Ramirez, Carlos, de Moor, J Maarten, Rodriguez, Alejandro, Hudak, Michael R, Subhas, Adam, Halldórsson, Sæmundur Ari, Stefánsson, Andri, Caracausi, Antonio, Lloyd, Karen G, Giovannelli, Donato, Seltzer, Alan
• Other Authors: #PLACEHOLDER_PARENT_METADATA_VALUE#, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Palermo, Palermo, Italia
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science 2023
• Subjects: noble gases; earth degassing; Iceland
• Online Access: http://hdl.handle.net/2122/16672; https://doi.org/10.1126/sciadv.adg2566

Mantle-derived noble gases in volcanic gases are powerful tracers of terrestrial volatile evolution, as they contain mixtures of both primordial (from Earth's accretion) and secondary (e.g., radiogenic) isotope signals that characterize the composition of deep Earth. However, volcanic gases emitted through subaerial hydrothermal systems also contain contributions from shallow reservoirs (groundwater, crust, atmosphere). Deconvolving deep and shallow source signals is critical for robust interpretations of mantle-derived signals. Here, we use a novel dynamic mass spectrometry technique to measure argon, krypton, and xenon isotopes in volcanic gas with ultrahigh precision. Data from Iceland, Germany, United States (Yellowstone, Salton Sea), Costa Rica, and Chile show that subsurface isotope fractionation within hydrothermal systems is a globally pervasive and previously unrecognized process causing substantial nonradiogenic Ar-Kr-Xe isotope variations. Quantitatively accounting for this process is vital for accurately interpreting mantle-derived volatile (e.g., noble gas and nitrogen) signals, with profound implications for our understanding of terrestrial volatile evolution. Published eadg2566 OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici JCR Journal