Volcanic fertilization of Late Triassic lacustrine algal blooms

Résumé fourni par la source

Although the productivity of modern volcanic soils is well established, the fertilization effects of ancient volcanic ash on aqueous ecosystems remains contentious. Here we demonstrate volcanic fertilization effects on a Late Triassic lacustrine ecosystem based on micropaleontological and geochemical records from the Yanchang Formation of North China. Frequent eruptions of a regional volcanic arc system increased cyanobacterial populations and organic carbon sinking fluxes, as recorded by extreme total organic carbon content (>30 wt.%) and positive organic carbon and negative nitrogen isotopic excursions. In turn, high levels of primary productivity induced intense water-column anoxia, facilitating preservation of organic matter. These findings underscore the potential influences of volcanism on ecological conditions, primary productivity, and carbon sequestration throughout geological history. In Late Triassic lake ecosystems, volcanic ash deposition boosted primary productivity, enhanced organic carbon sequestration, and triggered water-column anoxia, reshaping carbon cycling dynamics, according to geochemical, micropaleontological and sedimentological data from the Yanchang Formation, North China.

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