Constraining the depositional framework of lower carboniferous strata in northern Britain using stable-isotope chemistratigraphy

Prave, A., Fallick, A. and Robinson, R.A.J. (2010) Constraining the depositional framework of lower carboniferous strata in northern Britain using stable-isotope chemistratigraphy. In: Application of Modern Stratigraphic Techniques: Theory and Case Histories. Series: SEPM Special Publication (94). Society for Sedimentary Geology: Tulsa, USA, pp. 143-152. ISBN 9781565761995

Abstract

The Strathclyde and Clackmannan Groups comprise the Lower Carboniferous successions exposed in the eastern Midland Valley of Scotland (MVS) and adjacent areas of northern England. They form a thick succession (2–3 km in thickness) of similar-appearing shallow-marine to shoreline and fluvial–deltaic sandstones and shales punctuated by thin (typically < 1–2 m thick) shallow-marine carbonate rocks. This study obtained stable-isotope data on the carbonate units in order to assess the utility of C isotopes as an independent means of testing and refining stratigraphic correlations. The δ13 Ccarbonate data: (1) corroborate most of the lithostratigraphic correlations determined previously using other stratigraphic methodologies; (2) diagnose miscorrelations based on markedly different C-isotope profiles exhibited by carbonate units originally thought to be correlative; and (3) help discern patterns of varying rates of sediment flux and accommodation-space genesis across the eastern MVS basin. These results prove the utility of C-isotope profiles in helping construct and evaluate the stratigraphic framework of a sedimentary basin and highlight their usefulness as a tool that could be applied relatively quickly and inexpensively in areas of lesser-known geology and when time and financial investment are at a premium. The data also show that the Strathclyde Group has mostly negative C-isotope values (ca. -1 to -5‰) that shift abruptly to consistently positive values (0 to 2‰) at the contact with and into the overlying Clackmannan Group. Radiometric ages on volcanic rocks in the MVS constrain the negative interval to between ca. 343–335 Ma and that the shift to positive values occurred close to ca. 335 Ma. This trend coincides with a decline and recovery in δ13C trends documented in Visean rocks elsewhere and likely records a widespread (global?) shift in the isotopic composition of Early Carboniferous oceans.

• Item Type: Book Sections
• Keywords: Lower Carboniferous, stable isotopes, Britain, Scotland, Midland Valley, chemostratigraphy
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fallick, Professor Anthony
• Authors: Prave, A., Fallick, A., and Robinson, R.A.J.
• Subjects: Q Science > QE Geology
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Publisher: Society for Sedimentary Geology
• ISBN: 9781565761995
• Published Online: 01 January 2010