Rapid eruption of silicic magmas from the Paraná magmatic province (Brazil) did not trigger the Valanginian event

Rocha, Brenda C.; Davies, Joshua H.F.L.; Janasi, Valdecir A.; Schaltegger, Urs; Nardy, Antônio J.R.; Greber, Nicolas D.; Lucchetti, Ana Carolina F.; Polo, Liza A. (2020). Rapid eruption of silicic magmas from the Paraná magmatic province (Brazil) did not trigger the Valanginian event. Geology, 48(12), pp. 1174-1178. Geological Society of America 10.1130/G47766.1

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The Valanginian Stage is marked by a period of global positive δ13C carbon cycle perturba-tion and biotic crises, which are collectively referred to as the Valanginian event (VE). Many attempts have been made to link the Paraná-Etendeka large igneous province volcanism with the VE. However, currently there is no conclusive proof to support this hypothesis, since the timing and duration of the volcanic activity are not known with suf cient precision. In this study, we signi cantly revise the time scales of magmatism and environmental impact of the Paraná magmatic province (PMP) in Brazil with new high-precision zircon U-Pb ages from the low-Ti Palmas and high-Ti Chapecó sequences. Our data demonstrate that signi - cant volumes of low-Ti silicic rocks from the PMP erupted rapidly at ca. 133.6 Ma within 0.12 ± 0.11 k.y. The age of the high-Ti Chapecó sequence from central PMP is constrained at ca. 132.9 Ma and thus extends the duration of magmatic activity by ∼700 k.y. Our new ages are systematically younger than previous ages and postdate the major positive carbon isotope excursion, indicating that PMP silicic magmatism did not trigger the VE but could have contributed to extending its duration. Within the framework of the stratigraphic column of the PMP, the earliest low-Ti basalts could have been responsible for the VE if they are at least 0.5 m.y. older than the low-Ti silicic rocks dated herein.

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