10.6084/m9.figshare.3454220.v1 Emanuela Mattioli Emanuela Mattioli Bernard Pittet Bernard Pittet RaffaellaBucefalo Palliani RaffaellaBucefalo Palliani Hans-Joachim RÖhl Hans-Joachim RÖhl Annette Schmid-RÖhl Annette Schmid-RÖhl Elena Morettini Elena Morettini Phytoplankton evidence for the timing and correlation of palaeoceanographical changes during the early Toarcian oceanic anoxic event (Early Jurassic) Geological Society of London 2016 duration reactive neritic system crisis p CO 2 abundance magmatic activity matter excursion nannoplankton Carinolithus superbus nannofossil Zone Toarcian oceanic anoxic event Toarcian anoxic event correlation Geology 2016-06-21 11:58:59 Dataset https://geolsoc.figshare.com/articles/dataset/Phytoplankton_evidence_for_the_timing_and_correlation_of_palaeoceanographical_changes_during_the_early_Toarcian_oceanic_anoxic___event_Early_Jurassic_/3454220 <p>The causes and duration of the early Toarcian anoxic event are controversial. Integration of data from calcareous and organic phytoplankton provides a biochronological framework that allows precise correlations across the western Tethys. In particular, the <em>Carinolithus superbus</em> nannofossil Zone can be used to correlate the levels enriched in organic matter and the related <em>δ</em><sup>13</sup>C negative excursion. Although a variable duration is given in the literature for this negative excursion, it is likely that it lasted between 520 and 650 ka. Increased atmospheric <em>p</em>CO<sub>2</sub>, related to excess volcanic emissions (magmatic activity in the Karoo and Ferrar Provinces), had an impact on climate and ocean chemistry, and marked the inception of a biotic crisis affecting many organisms. The beginning of the crisis within shallow carbonate platforms, documented at southern latitudes, predates the levels enriched in organic matter. Dinoflagellate cysts experienced a decrease in abundance in the <em>C. superbus</em> Zone, until they temporarily disappeared. The nannoplankton crisis was twofold: a decrease in size and low calcified specimens are observed in addition to a drastic decrease in absolute abundance. The increased atmospheric <em>p</em>CO<sub>2</sub>, as a result of the magmatic activity and temporarily amplified by transient methane release, could have been the trigger for the biocalcification crisis, which first affected the probably more reactive neritic system, and eventually the nannoplankton community. </p>