EP069-05
Mercury as a proxy for enhanced volcanism across the Palaeocene-Eocene Thermal Maximum (PETM)

Thursday, 17 December 2020: 07:13
Virtual
Maxime Tremblin1, Hassan Khozyem2, Jorge Spangenberg3, Charlotte Fillon4, Arnaud Grauls5, Lasseur Eric6, Olivier Serrano6, Jean-Yves Roig6, Sylvain Calassou4, Francois Guillocheau7, Thierry Adatte8 and Sebastien Castelltort1, (1)University of Geneva, Department of Earth Sciences, Geneva, Switzerland, (2)Aswan University, Departement of Geology, Aswan, Egypt, (3)University of Lausanne, Institute of Earth Surface Dynamics, Lausanne, Switzerland, (4)TOTAL S.A, Centre Scientifique et Technique Jean Féger, Pau, France, (5)TEREGA, Department of Geosciences, Pau, France, (6)BRGM, French Geological Survey, Orléans, France, (7)Université de Rennes, Géosciences Rennes, Rennes, France, (8)University of Lausanne, Institute of Earth Sciences, Lausanne, Switzerland
Abstract:
The Paleocene-Eocene thermal maximum (PETM; ~55.6 Ma) is characterized by a global warming and a significant perturbation of the carbon cycle. This event is registered in the geological record by a sharp negative carbon isotope excursions (NCIE) in both carbonates and organic matter. The source of the 13C-depleted carbon for the NCIE and whether it was released in one or several events is still debated. The large release of carbon associated with the development of large igneous provinces (LIPs) is suspected to be one of the mechanisms which triggered this abrupt climate upheaval. Mercury (Hg) anomalies is now commonly used as a marker of volcanism and can therefore provide hints on the possible relationship between the development of LIPs and the environmental changes associated with the PETM.

Here we present new high-resolution mercury and stable isotopic records from peripheral basins of the Pyrenean orogen across the PETM. The high sedimentation rates which characterize these environments make them ideally suitable to provide a high-resolution record of carbon and Hg cycle perturbations during the PETM.

The data obtained at the different studies sites reveal the occurrence of two main NCIEs. Based on biostratigraphy and similarity of shape and amplitude of the isotopic excursions with global records, the largest NCIE is interpreted as the PETM. This main excursion is immediately preceded by another one that we interpret as the Pre-Onset Excursion (POE), found in few other profiles worldwide. These two NCIEs are both systematically associated with important Hg anomalies. These results show that pulses of volcanism, probably associated to the emplacement of the North Atlantic Igneous Province, contributed to the onset and to the long duration of the PETM. In addition, our study highlights the possibility to get reliable information about past extreme climate events from sediments successions deposited within active tectonic domains. Finally, our geochemical record allows to define robust isochronous lines and thus to propose a stratigraphic correlation between sections of the Pyrenean orogenic chain deposited in different palaeogeographical domains during the Paleogene.

This work is financed and carried out within the framework of the BRGM-TOTAL Source-to-Sink project.

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