The Carnian Pluvial Episode in Tethys Realm: Insights from multiproxy paleoclimate data

The Carnian Pluvial Episode (CPE, 234–232 Ma) was a major climate change event in the Triassic. The CPE brought substantial changes in ecological community structure and the appearance of many key groups dominating modern marine and terrestrial ecosystems. Here we present an interdisciplinary study of Upper Triassic strata in the Tethys realm to reconstruct the vegetation history and infer environmental changes during the Carnian. Furthermore, we applied Mercury (Hg) concentrations and Total Organic Carbon (TOC) to unwrap the role of volcanic activity as a major driver of this episode of climate warming and environmental perturbations. Palynological and paleobotanical data collected from the Northern Tethys (Kope-Dagh basin, NE Iran) show a shift towards hygrophytic elements reflecting the expansion of wet habitats on the continent during the latest early Carnian to late Carnian. The sedimentological and palynological patterns and plant fossil assemblages in the Northern Tethys closely resemble those observed in Western Tethys during CPE. This record represents the only clear record of the CPE in the Iranian plateau. Our geochemical data from Carnian marine sedimentary sequences of the Western Tethys demonstrate discrete spikes in Hg/TOC ratios during the CPE. The results suggest a direct link between the CPE and repeated pulses of the Wrangellia submarine Large Igneous Province that could have played a major role in the evolution of biota and the environment at that time. However, despite progress in understanding the CPE, significant uncertainty remains in addressing how the volcanic eruptions influenced different ecosystems/biotic communities, which deserves further studies.