View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Plymouth Electronic Archive and Research Library 1 2 3 Combined sea–level and climate controls on limestone formation, hiatuses and ammonite 4 preservation in the Blue Lias Formation, South Britain (uppermost Triassic–Lower 5 Jurassic) 6 7 Short title/running head: Sea level and climate controls of the Blue Lias 8 9 Graham P. Weedon1*, Hugh C. Jenkyns2 and Kevin N. Page3 10 11 * Corresponding author 12 1
[email protected], Met Office, Maclean Building, Benson Lane, 13 Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK. 14 2 Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, 15 UK. 16 3 School of Geography, Earth and Environmental Sciences, Plymouth University, Drakes 17 Circus, Plymouth, PL4 8AA, UK. 18 19 20 21 In press: Geological Magazine 22 23 January 2017 24 1 25 Abstract 26 Lithostratigraphic and magnetic-susceptibility logs for four sections in the Blue Lias 27 Formation are combined with a re-assessment of the ammonite biostratigraphy. A Shaw plot 28 correlating the West Somerset coast with the Devon/Dorset coast at Lyme Regis, based on 63 29 common biohorizon picks, together with field evidence, demonstrate that intra-formational 30 hiatuses are common. Compared to laminated shale deposition, the climate associated with 31 light marl is interpreted as both drier and stormier. Storm-related non-deposition favoured 32 initiation of limestone formation near the sediment-water interface. Areas and time intervals 33 with reduced water depths had lower net accumulation rates and developed a greater proportion 34 of limestone.