Early Jurassic mutations: Phytotoxicity due to Hg-remobilization

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The occurrence of malformations in spores and pollen has been described from several boundary sections associated with mass extinction events across Europe and North America. The emplacement of Large Igneous Provinces has been invoked as the main trigger for the formation of abnormal morphologies in terrestrial palynomorphs during the end-Permian and end-Triassic crises. However, the exact pathways through which volcanism impacts vegetation remains unclear and proposed scenarios include extensive climate change leading to wildfire activity, pathogen outbreaks, acid rain, and increased UV-B radiation due to ozone depletion. More recently, volcanogenic mercury (Hg) has been implicated as the cause for mutations in spores/pollen indicating severe ecological stress in terrestrial vegetation. Sedimentary Hg-enrichments have been used for tracing volcanic activity, but dynamics of the Hg-cycle are poorly understood in deep time. Based on Early Jurassic (Hettangian + Sinemurian) palynofloral reconstructions and Hg-concentrations of shallow marine deposits in central Germany, we bring to light rapid and periodic shifts in malformed spores coinciding with rapid fluctuations in the regional carbon cycle, weathering indicators and Hg-enrichments. Similarly, increased mutagenic spore abundances with accompanying Hganomalies are noted across the end-Triassic mass-extinction and within the lowermost Hettangian, consistent with studies from Sweden and Denmark and, therefore, confirming synchronous mutagenesis in and around coastal European margins. The cyclic pacing throughout the Hettangian assemblages indicates forcing mechanisms other than volcanism to be impacting regional climate with signs of repeated phytotoxicity. Extreme seasonality alternating between high rainfall and droughts, likely due to orbital variation, leading to increased wildfires, soil erosion and transport/degradation of terrestrial OM, probably redistributed Hg stored in soil and/or bedrock reservoirs. These implications suggest a more dominant role of climate-induced Hg-remobilization, rather than direct volcanic emissions, to sedimentary Hg-enrichment with potential phytotoxic consequences
Original languageEnglish
Publication date2022
Number of pages1
Publication statusPublished - 2022
Event11th European Palaeobotany and Palynology Conference - Stockholm, Sweden
Duration: 19 Jun 202222 Jun 2022
Conference number: 11


Conference11th European Palaeobotany and Palynology Conference
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