Carbon isotopic evidence for organic matter oxidation in soils of the Old Red Sandstone (Silurian to Devonian, South Wales, UK)

A T Brasier, J L Morris, R D Hilier

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Petrographic and calcrete carbon isotope data from seasonally waterlogged Upper Silurian (Pridoli) to Lower Devonian (Pragian) palaeo-Vertisols of the Old Red Sandstone, South Wales, UK, are presented. The delta C-13 values mostly range from -9 to -12% (VPDB), suggesting that the soils were inhabited by abundant vegetation that when oxidized (perhaps with microbial assistance) resulted in CO2-rich soils. Such soils would favour calcrete precipitation through equilibration of soil zone CO2 with the relatively lower atmospheric pCO(2). However, reliably estimating palaeoatmospheric pCO(2) using these carbon isotope data is a challenge.

Original languageEnglish
Pages (from-to)621-634
Number of pages14
JournalJournal of the Geological Society
Issue number5
Early online date7 Jul 2014
Publication statusPublished - Sep 2014


  • Anglo-Welsh basin
  • ridgeway conglomerate formation
  • atmospheric CO2
  • pedogenic carbonate
  • SW Wales
  • Paleozoic atmosphere
  • Bloomsburg formation
  • phanerozoic time
  • vertic paleosols
  • Townsend-Tuff

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