High precision noble gas measurements of hydrothermal quartz reveal variable loss rate of Xe from the Archean atmosphere

Determining the composition of Archean atmosphere and oceans is vital to understanding environmental conditions that existed on surface early Earth. The analysis atmospheric remnants in fluid inclusions trapped Archean-aged samples has shown Xe isotopic signature progressively evolved via mass-dependent fractionation, arriving at a modern around Archean-Proterozoic transition. mechanisms driving this evolution are however not well constrained, it yet clear whether proceeded continuously or episodic bursts. Providing further constraints hampered by limited amounts gas within during mineral formation, which impacts precision can be determined. Here, we develop new crush-and-accumulate extraction technique enables heavy noble gases (Ar, Kr Xe) released from crushing large quantities hydrothermal quartz accumulated analysed higher than was previously possible. Using technique, re-evaluate 3.3 Ga Barberton, South Africa. We find fractionated +10.3 ± 1.0‰u?1 (2 SE) relative atmosphere, uncertainty of, but slightly lower than, previous determination 12.9 2.4‰u?1 for sample (Avice et al., 2017). show first time Kr/Xe ratio measured enriched compared demonstrating lost since Archean. This reinforces proposal escape as primary mechanism Earth's loss. isotope fractionation recorded Barberton incompatible with model describing loss continuous rate under constant factor. gives credence numerical models hydrodynamic escape, suggest bursts rather rate. Refining curve isotopes using presented here potential shed light discrete events punctuated Earth accompanied life.