Observable feature (chemical, morphological, isotopic, spectral) whose presence is a plausible indicator of life. Atmospheric: O₂/O₃ + CH₄ disequilibrium; isotopic: ¹³C depletion in organic matter (δ¹³C < –20‰); morphological: microfossils…
Observable feature (chemical, morphological, isotopic, spectral) whose presence is a plausible indicator of life. Atmospheric: O₂/O₃ + CH₄ disequilibrium; isotopic: ¹³C depletion in organic matter (δ¹³C < –20‰); morphological: microfossils…