Hydrogeochronology: Resetting the timestamp for subsurface groundwaters

Warr, Oliver; Smith, N. J. T.; Lollar, Barbara Sherwood

doi:10.1016/j.gca.2023.03.017

Cited by 6 publications

(1 citation statement)

References 101 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The DIC concentration of each Moab Khotsong brine is much less than the 1200-level (83.7 mg C / L) with the δ 13 C of this site (−11.4‰) reflecting substantial dolomite dissolution. The Δ 14 C values reported here suggest negligible modern surface recharge and considerable in-situ generation of 14 C. This can occur via neutron capture reactions relating to the high U (≥100 ppm) and Th (≥100 ppm) concentrations from the proximal Vaal Reef (Supplementary Information), a process that has been proposed in the literature 57 , but only recently quantitatively evaluated for 14 C and related tracers in the continental subsurface 58 , 59 .…”

Section: Discussionmentioning

confidence: 69%

Radiolytically reworked Archean organic matter in a habitable deep ancient high-temperature brine

Nisson,

Walters,

Chacón-Patiño

et al. 2023

Nat Commun

Self Cite

View full text Add to dashboard Cite

Investigations of abiotic and biotic contributions to dissolved organic carbon (DOC) are required to constrain microbial habitability in continental subsurface fluids. Here we investigate a large (101–283 mg C/L) DOC pool in an ancient (>1Ga), high temperature (45–55 °C), low biomass (102−104 cells/mL), and deep (3.2 km) brine from an uranium-enriched South African gold mine. Excitation-emission matrices (EEMs), negative electrospray ionization (–ESI) 21 tesla Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and amino acid analyses suggest the brine DOC is primarily radiolytically oxidized kerogen-rich shales or reefs, methane and ethane, with trace amounts of C3–C6 hydrocarbons and organic sulfides. δ2H and δ13C of C1–C3 hydrocarbons are consistent with abiotic origins. These findings suggest water-rock processes control redox and C cycling, helping support a meagre, slow biosphere over geologic time. A radiolytic-driven, habitable brine may signal similar settings are good targets in the search for life beyond Earth.

show abstract

Section: Discussionmentioning

confidence: 69%