δ¹³C_carb data recording the early Sheinwoodian carbon isotope excursion on the Midland Platform, UK

Abstract

δ¹³C_carb data from the Tortworth and Woolhope inliers, Midland Platform, UK, provide a record of part of the early Sheinwoodian (Ireviken) carbon isotope excursion. The shallow-marine mixed carbonate/siliciclastic successions exhibit a maximum δ¹³C_carb value of +5.8‰ VPDB. Values begin to increase sharply at the Pycnactis Band, a prominent flooding surface, and decrease over a transgressive sequence between the Woolhope and Coalbrookdale formations. The study provides an improved chronostratigraphic correlation across the Sheinwoodian of the Midland Platform (Avalonia) and further afield, and highlights the power of integrated chemostratigraphy and sequence stratigraphy in the absence of well-developed biostratigraphy.

Keywords::

• Avalonia
• Ireviken
• positive carbon isotope excursion
• Sheinwoodian
• Silurian

Acknowledgements

We thank English Nature, and Philip Robertson and David Watts for access to Brinkmarsh and Scutterdine quarries, respectively. Fieldwork and laboratory analyses costs were covered by the Palaeontological Association Research Grant. Alan Thomas and Živilė Žigaitė are acknowledged for initial investigations into the nature of the phosphatic grains from selected beds in Brinkmarsh Quarry. Patrick McLaughlin and Dimitri Kaljo are thanked for their comments. This is a contribution to the International Geoscience Programme (IGCP) Project 591 – The Early to Middle Palaeozoic Revolution.