High- to Mid-Latitude Perspectives on the Carnian Pluvial Episode: Integrated Stratigraphy from Svalbard and Northern Ireland

The Late Triassic Carnian Pluvial Episode (CPE, ~232 Ma) represents a major global climatic perturbation, marked by a shift from arid to humid and wet conditions, followed by a return to aridity. The CPE is widely recorded in both marine and terrestrial successions around the world and has been linked to a global carbon cycle perturbation associated with the emplacement of the Wrangellian Terrain Large Igneous Province (WT-LIP, ~231-225 Ma). Here we present new high-resolution, integrated stratigraphic datasets from two Carnian successions in Laurasia that capture complementary mid- and high-latitude responses to the CPE: the Knocksoghey Formation (Mercia Mudstone Group) in the Carnduff-1 core, Northern Ireland, representing playa-lake to aeolian deposits; and the De Geerdalen Formation (Kapp Toscana Group) in the DH-4 core, Svalbard, spanning deltaic to shallow-marine settings. Using a multi-proxy approach that integrates carbon isotopes, elemental geochemistry, weathering indices, clay mineralogy, and Hg/TOC ratios, we assess the timing and expression of carbon-cycle perturbation, intensified hydrological cycling, and potential volcanic forcing. In the Knocksoghey Formation, coarse siliciclastic beds termed as ‘Skerries’ disrupt the otherwise monotonous fine-grained red palaeosols, consistent with increased runoff and enhanced weathering during the humid phase. This lithological shift is preceded by elevated Hg concentrations, a stepped negative carbon-isotope excursion of ~-6‰, and a synchronous increase in geochemical weathering proxies. Comparison of our Hg/TOC and δ¹³C data with published CPE records highlights a recurrent association between elevated Hg/TOC and the onset of the negative δ¹³C excursion, mirroring patterns documented for other large igneous province (LIP)-driven Mesozoic climate perturbations. These findings support the interpretation that WT-LIP volcanism was the driving mechanism behind the CPE.