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The Rotalipora cushmani extinction at Gubbio (Italy): Planktonic foraminiferal testimonial of the onset of the Caribbean large igneous province emplacement?

By
Rodolfo Coccioni
Rodolfo Coccioni
Dipartimento di Scienze Pure e Applicate, Università degli Studi di Urbino “Carlo Bo,” Campus Scientifico, Località Crocicchia, 61029 Urbino, Italy
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Marianna Sideri
Marianna Sideri
Dipartimento di Scienze Pure e Applicate, Università degli Studi di Urbino “Carlo Bo,” Campus Scientifico, Località Crocicchia, 61029 Urbino, Italy
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Fabrizio Frontalini
Fabrizio Frontalini
Dipartimento di Scienze Pure e Applicate, Università degli Studi di Urbino “Carlo Bo,” Campus Scientifico, Località Crocicchia, 61029 Urbino, Italy
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Alessandro Montanari
Alessandro Montanari
Osservatorio Geologico di Coldigioco, 62021 Apiro, Italy
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Published:
July 01, 2016

The highest stages of the stratigraphic range of the planktonic foraminiferal Rotalipora cushmani were investigated in a 313-k.y.-long interval of the classical Tethyan Bottaccione section (Gubbio, Italy), the type locality of the Corg- rich Bonarelli Level, which is the sedimentary expression of the worldwide latest Cenomanian oceanic anoxic event 2 (OAE 2).The disappearance of R. cushmani is associated with the major turnover of marine microfauna and microflora that involves both planktonic and benthic foraminifera, and calcareous nannofossils, slightly before the onset of OAE 2, which, according to current available data, was triggered by a massive pulse of submarine mafic volcanism accompanying the initial emplacement of the Caribbean large igneous province (CLIP). This pulse of volcanic activity probably turned the climate in a strengthened greenhouse mode, accelerating continental weathering and increasing nutrient supply in oceanic surface waters via river runoff and triggering higher fertility in the global ocean. Our investigation shows that the marine biotic turnover started ~55 k.y. before the onset of OAE 2 and is closely coeval with the first major episode, as recorded by the unradiogenic trend in 187Os/188Os, of the ongoing magmatic activity of the CLIP, which produced increasing pCO2, ocean dissolution and/or acidification with a severe carbonate crisis and fertilization through enormous quantities of biolimiting metals. The marine microfauna and microflora reacted rapidly to new conditions of higher pCO2 and fertility by undergoing marked changes following three main steps. We evaluate this pattern and postulate that the first pulse of volcanogenic CO2 from the CLIP emplacement (ca. 94.2 or 94.6 Ma) played a fundamental role in the marine biotic turnover recorded shortly before the onset of OAE 2 and notably in the local or regional disappearance of R. cushmani in the central-western Tethys.

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GSA Special Papers

The Stratigraphic Record of Gubbio: Integrated Stratigraphy of the Late Cretaceous–Paleogene Umbria-Marche Pelagic Basin

Marco Menichetti
Marco Menichetti
Dipartimento di Scienze Pure e Applicate, Universita` degli Studi di Urbino, 61029 Urbino (PU), Italy
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Rodolfo Coccioni
Rodolfo Coccioni
Dipartimento di Scienze Pure e Applicate, Universita` degli Studi di Urbino, 61029 Urbino (PU), Italy
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Alessandro Montanari
Alessandro Montanari
Osservatorio Geologico di Coldigioco, Cda. Coldigioco 4, 62021 Apiro (MC), Italy
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Geological Society of America
Volume
524
ISBN print:
9780813725246
Publication date:
July 01, 2016

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