Abstract
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 language | English |
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Pages (from-to) | 621-634 |
Number of pages | 14 |
Journal | Journal of the Geological Society |
Volume | 171 |
Issue number | 5 |
Early online date | 7 Jul 2014 |
DOIs | |
Publication status | Published - Sept 2014 |
Bibliographical note
This work was part-supported by a grant from the E. J. Garwood Fund (2011) of the Geological Society of London. J. Dougans (SUERC) and S. Verdegaal (VU Amsterdam) kindly assisted with some of the stable isotope measurements. D. Brasier kindly assisted with fieldwork. Work on Tredomen Quarry calcrete samples was conducted by J.L.M. as part of a PhD thesis funded by the School of Earth and Ocean Sciences, Cardiff University, under the supervision of V. P. Wright and D. Edwards. Core drilling was partly funded by the British Geological Survey. Thanks go to J. Becker (Cardiff University) for isotopic analysis of the Tredomen Quarry calcretes, and to G. Abbott (Newcastle University) and Iso-Analytical Ltd for isotopic analysis of fossil plant material. Three anonymous reviewers and the editor made helpful suggestions that improved the quality of the paper.Keywords
- Anglo-Welsh basin
- ridgeway conglomerate formation
- atmospheric CO2
- pedogenic carbonate
- SW Wales
- Paleozoic atmosphere
- Bloomsburg formation
- phanerozoic time
- vertic paleosols
- Townsend-Tuff