Abstract

The generally arid Late Triassic climate was interrupted by a wet phase during the mid Carnian termed Carnian Pluvial Episode (CPE). Quantitative palynological data from the Mercia Mudstone Group in the Wessex Basin (UK), reveals vegetation changes and palaeoclimate trends. Palynostratigraphy and bulk organic carbon isotope data enable correlation to other Carnian successions. The palynostratigraphy indicates that the Dunscombe Mudstone is Julian and the lowest part of the overlying Branscombe Mudstone Formation is Tuvalian.. The Aulisporites acme characterizing the CPE in Tethyan successions and the Germanic Basin, is missing in the UK. The quantitative palynological record suggests the predominance of xerophyte floral elements with a few horizons of increased hygrophytes. A humidity signal is not seen due to the dry climate in central Pangea. Secondly, the signal might be masked by the overrepresentation of xerophyte regional pollen and the predominance of xerophyte hinterland flora. The bias towards regional pollen rain is enhanced by the potential increase in continental runoff related to seasonally humid conditions and differences in pollen production rates and transport mechanisms. The vegetation of British CPE successions suggests a more complex climate history during the Carnian indicating that the CPE is not recognized by the same changes everywhere.

Supplementary material: Detailed lithological log of the Strangman's Cove (Devon) outcrop with the description of the MMG lithostratigraphical units, description of the laboratory techniques, seven photoplates with selected spores and pollen grains, a list of all identified palynomorphs, Excel sheets with the palynological and palynofacies counts, bulk organic carbon isotope ratios and TOC values of the Strangman's Cove outcrop are available at https://doi.org/10.6084/m9.figshare.c.4138085

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