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Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid. Recovered only hours after falling, the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment. It contains abundant hydrated silicates formed during fluid-rock reactions, and carbon- and nitrogen-bearing organic matter including soluble protein amino acids. The near-pristine hydrogen isotopic composition of the Winchcombe meteorite is comparable to the terrestrial hydrosphere, providing further evidence that volatile-rich carbonaceous asteroids played an important role in the origin of Earth’s water.

Highlights-Controls on NeH + formation are determined, and 20 NeH + formation is precisely quantified on the basis of measured 22 NeH +-21 Ne/ 20 Ne of air has been re-determined to be 0.002959 ± 0.000004 (0.14%, 1σ)-The lower uncertainty of air 21 Ne/ 20 Ne and better precision of Ne isotope analyses significantly reduces the uncertainty of Ne concentration measurements, essential for development of cosmogenic and radiogenic dating applications

The late Carboniferous-early Permian coal seams of the Qinshui Basin in Shanxi Province are the most prolific producer of coalbed methane (CBM) in China. Methane formed in the late Triassic during deep burial and reheating in late Jurassic-early Cretaceous driven by magmatic underplating. Basin inversion brought the coal seams to 400-700 m from the surface in the mid-late Cenozoic. Here we present results of a study aimed at understanding the origin of the methane, and how it was affected by Cenozoic exhumation of the basin. Methane from a 12 km traverse perpendicular to the basin margin in the southeast part of the basin have stable isotope compositions (δ 13 C =-30.2 to-35.2‰, and δD =-155 to-194‰) indicating a thermogenic origin with limited biogenic input. They are, however, lighter than expected based on coal maturity, and C1/(C2+C3) (>1000) are significantly higher than typical thermogenic methane (<50). This is due to diffusive fractionation during commercial gas extraction. He-NeAr isotopes are a mixture of crustal-radiogenic gas with air-derived noble gases. 4 He concentrations (0.52 to 33.25 ppmv) and 4 He/ 40 Ar * ratios (0.06-1.74) are unusually low. He-NeAr concentrations are consistent with the open system Rayleigh fractionation of noble gases derived from air-saturated water with 4 He/ 40 Ar * = 1 during gas extraction. The low 4 He/ 40 Ar * , compared with average crust (5) or local production (13) values, implies that more than 90% of the radiogenic 4 He produced in the coals has been lost prior to equilibrium between gas and water phase in the reservoir. This likely occurred in response to gas loss process during rapid exhumation in Cenozoic, showing that the He and Ar content of natural gases is a sensitive indicator of gas loss event caused by recent basin inversion. The event may have led to the loss of up to 44% of the methane from the coal seams. This study demonstrates the importance of basin inversion on gas preservation in shallow CBM, and shows that, in contrast to δ 13 CCH4, the light noble gases are essential for tracing such a process. Keywords Coalbed methane (CBM), Southeast Qinshui basin, noble gas isotopes, gas loss, high coal rank Highlights  Gas compositions and stable isotopes indicate diffusive fractionation during commercial gas extraction.  There is no indication of mantle volatiles in gas samples, no evidence of mantle heating during the Yanshanian Orogeny.  The low radiogenic He and He/Ar ratio indicate loss of free gas during basin exhumation.

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