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CO2 budget of Eocene Iranian magmas and their potential contribution to the Middle Eocene Climatic Optimum

Lea Ostorero 1, Rosario Esposito1, Pierre Bouilhol2, Paolo Ballato3, Veleda Astarte Müller4, Maria Luce Frezzotti1, Pietro Sternai1,5

  • Affiliations:  1Department of Earth and Environmental Sciences - DISAT, University of Milano‐Bicocca, Piazza dell'Ateneo Nuovo, 1 -- 20126, Milan, Italy; 2Université de Lorraine, CNRS, CRPG, F-54000 Nancy, France; 3Department of Science, Roma Tre University, Roma, Italy; 4Department of Geosciences, University of Arizona, Tucson, USA; 5GFZ German Research Centre for Geosciences, Potsdam, Germany 

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 4

  • Programme No: 6.1.10

  • Theme 6 > Session 1

Abstract

Emissions of CO2 from magmatic arcs can affect the atmosphere composition, thereby driving long-term global climate changes. Early Cenozoic climate trends are generally associated with changes in global silicate weathering related to Neo-Tethyan geodynamics, but the likely climatic effects of changes in degassing from Neo-Tethyan magmatic arcs have been poorly quantified. Here, we provide the first measures of the volatile content (CO2, H2O, F, Cl and S) of pre-eruptive melts based on glassy, bubble-bearing and reheated melt inclusions within plagioclase and clinopyroxene crystals in Early Cenozoic trachyandesites from the Alborz and Tabriz regions (Iran). CO2 concentrations in these melt inclusions reach up to 6733 ppm, thus providing a minimum estimate of the total amount of CO2 released from the Iran magmas during the middle-late Eocene of 1.01.1019 g CO2, with a total C flux released from those magmas of 0.306 (± 0.123) Mt C/yr. Our findings support earlier hypotheses that magmatic CO2 degassing from the target igneous provinces played a role in the Middle Eocene Climatic Optimum. Therefore, additional measurements of the volatile contents of Neo-Tethyan magmas are essential to assess the drivers of Early Cenozoic climate trends and to understand the global cycling of volatiles over geological timescales.