@article{57c887a2769844e3ae5c730205ea330b,
title = "Integrated stratigraphical study of the Rhuddanian-Aeronian (Llandovery, Silurian) boundary succession in the Rheidol Gorge, Wales: A proposed Global Stratotype Section and Point for the base of the Aeronian Stage",
abstract = "The Rheidol Gorge section, approximately 17 km east of Aberystwyth, mid Wales, exposes a ca. 20 m-thick succession of Llandovery (Silurian) strata from the upper Rhuddanian Pernerograptus revolutus Biozone through the lower Aeronian Demirastrites triangulatus Biozone and basal Neodiplograptus magnus Biozone. The section records deposition under a range of bottom-water oxygenation states. The Rhuddanian-Aeronian boundary is located 0.8 m above an abrupt lithological change from predominantly organic-poor, bioturbated {\textquoteleft}oxic{\textquoteright} mudrocks to an interval of black, richly graptolitic {\textquoteleft}anoxic{\textquoteright} shales. The graptolite fauna through the boundary interval, including the local lowest occurrence of D. triangulatus, allows precise correlation with other parts of the world. Graptolite assemblages indicative of separate divisions in the underlying revolutus Biozone and of the lower and upper parts of the triangulatus Biozone are also present. Chitinozoans are relatively well preserved in the section and indicate the Spinachitina maennili Biozone throughout the boundary interval, as is widely the case. The results of carbon isotope analyses from organic matter indistinctly show the weak interval of positive shift in δ13Corg values through the Rhuddanian-Aeronian boundary interval, as observed globally, though local or regional processes appear largely to overprint the global signal. Overall, the excellent biostratigraphical record, well-documented local and regional stratigraphical context, historical significance, as well as easy access and assured longterm preservation, mean that the Rheidol Gorge section can be proposed as a strong candidate for a new Global Stratotype Section and Point for the base of the Aeronian Stage.",
keywords = "Aeronian, Carbon Isotopes, Chitinozoa, Global Stratotype Section and Point, Graptolites, Llandovery, Rhuddanian, Silurian",
author = "Melchin, {Michael J.} and Davies, {Jeremy R.} and Arnoud Boom and {DE WEIRDT}, Julie and McIntyre, {Andrew J.} and Catherine Russell and Vandenbroucke, {Thijs R.A.} and Zalasiewicz, {Jan A.}",
note = "Funding Information: Acknowledgements.– We thank R. Melchin, M. Williams, J. Wilkinson, R. Waters, and B. Davies for assistance with the field work, and M. Riley for providing access to specimens in the Sedgwick Museum. R. Melchin also provided laboratory assistance in the study of the graptolites. MJM acknowledges financial support from a Natural Sciences and Engineering Research Council of Canada Discovery Grant, the Department of Geology, University of Leicester, for providing facilities to study our graptolite collections there, and M. Williams for invaluable help with logistics and informative discussions regarding the stratigraphy. We acknowledge the Palaeontological Association for financial support through a research grant for field work in 2011–2012, and the International Subcommission on Silurian Stratigraphy (ISSS) for financial support for the field trip of the 2016 IGCP 591 meeting, which facilitated collection of additional samples in 2016. Sabine Van Cauwenberghe (Ghent University) and Laurence Debeauvais (Lille University) for laboratory preparation, and Philippe Recourt (Lille University) for scanning electron microscopy. Additional data were partly generated using research infrastructure funded through FWO grant I013118N. We also thank Jacques Verniers and Margaret Sudbury for helpful discussions, and Petr {\v S}torch and an anonymous reviewer for their very useful and detailed comments on this manuscript. Publisher Copyright: {\textcopyright} 2023 Author(s).",
year = "2023",
month = feb,
day = "21",
doi = "10.18261/let.56.1.8",
language = "English",
volume = "56",
journal = "Lethaia",
issn = "0024-1164",
publisher = "Scandinavian University Press",
number = "1",
}