Early Jurassic schizosphaerellid crisis in Cantabria, Spain: Implications for calcification rates and phytoplankton evolution across the Toarcian oceanic anoxic event

摘要: [1] The Toarcian oceanic anoxic event (∼183 Myr ago) represents a global perturbation marked by increasing organic carbon burial and general decrease in calcium carbonate production likely triggered elevated dioxide levels the atmosphere. Here we present quantitative analyses of calcareous nannofossil diversity abundance from Castillo de Pedroso section Cantabria, northern Spain. We compare these data with geochemical (C O isotopes) obtained biogenic bulk records order to highlight response phytoplankton major climatic paleoceanographic changes. The Pliensbachian/Toarcian boundary is characterized an abrupt Schizosphaerella punctulata, most important lithogenic contributor (hemi) pelagic carbonates Early Jurassic. early nannofloral assemblages show increase Mitrolithus jansae small-sized r-selected taxa progressive S. punctulata percentages. deep dwellers M. experienced crisis slightly prior deposition black shales that are high abundances eutrophic such as Lotharingius spp. Biscutum return associated lower percentages was observed just above shales. episode reveals CO2 primary productivity probably shift highly calcified nannoliths coccoliths overall record biocalcification at onset during episode.