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Palynology and weathering proxies reveal climatic fluctuations during the Carnian Pluvial Episode (CPE) (Late Triassic) from marine successions in the Transdanubian Range (western Hungary)

Baranyi, Viktória, Rostási, Ágnes, Raucsik, Béla, Kürschner, Wolfram Michael
Global and planetary change 2019 v.177 pp. 157-172
Triassic period, carbonates, clay, climatic factors, humid zones, hydrolysis, kaolinite, marl, palynology, runoff, vegetation, Hungary
In the early Late Triassic, the Carnian Pluvial Episode (CPE) is a phase with increased siliciclastic influx into the marine-carbonate dominated depositional setting of the Western Tethys assumingly caused by a shift to more humid climatic conditions and increased continental runoff. Here, vegetation changes inferred from the palynological assemblages and weathering proxies (αAli) have been studied from the Transdanubian Range (TR), western Hungary to reveal climate variations and detect episodes with hygrophytic vegetation and enhanced continental hydrolysis. Palynostratigraphy has been applied to correlate the clastic pulses known from elsewhere in the Western Tethys. The quantitative palynological analysis indicates a shift towards hygrophytic elements in the Julian 2, and return to xerophytic associations in the Tuvalian. The increase in the hygrophytic vegetation elements is coincident with elevated kaolinite and partially with the increase of α-values indicating strong terrestrial runoff, enhanced continental hydrolysis and more humid climate in the lower part of the Veszprém Formation in the early Julian 2. The wetter conditions in the Julian 2 were periodically interrupted by shorter periods of drier climate manifested in the progradation of carbonate platforms and the deposition of carbonate series and breccias interbedded between the marl units. In the late Julian 2 the high amount of hygrophytes points to another humid episode, but the decrease of kaolinite in the clay mineral profile and the weathering indices might suggest stronger seasonality. Although, the multiple clastic pulses in the western Tethys were related primarily to more humid climate during the CPE, the comparison to clay mineralogy and weathering proxies suggest a more complicated scenario in the TR. The enhanced continental weathering related to a more humid climate is only suggested for the lower part of the Veszprém Formation in the early stages of the CPE in the Julian 2.