Carbon dioxide emissions from Aiken Spring in a Mars-analog desert region of the Qaidam Basin, Tibetan Plateau

Abstract

<p>Groundwater discharge from natural springs commonly involves gas emissions, providing valuable insights into the origin of spring and subsurface geology. Here, we report substantial carbon dioxide (CO2) emissions, instead of methane (CH4), from Aiken Spring, which is located in a desert region of the western Qaidam Basin, a Mars-analog environment within the Tibetan Plateau. The CO2 fluxes from the spring water surface reach up to 43.7 g/m2/h, with the estimated total emissions from the entire spring reaching at least 207 tons in the summer (90 days). The carbon (C) isotopic composition of the CO2 released from the spring is − 8.9 ± 1.6‰, which corresponds to an estimated value for dissolved inorganic carbon (DIC) of − 4.6 ± 1.6‰ in the original spring water, suggesting a mixture of mantle-derived CO2 and sedimentary carbonates. The mantle-derived CO2 at Aiken Spring may indicate active subsurface magmatic degassing within the intersection of the Altyn Tagh Fault and the Kunlun Fault, but it is more likely linked to a subsurface CO2 reservoir from ancient magmatic activity. Overall, our results indicate that Aiken Spring provides insights into deep subsurface geological processes and potentially the terrestrial subsurface biosphere.</p>