Sabin Zahirovic opened the meeting with an overview of how tectonic evolution has influenced the exchange of carbon between mantle and surface reservoirs, and how we can apply the latest digital community plate tectonic reconstructions to better understand this process for the past one billion years of Earth’s history. This was followed by three keynote presentations, including an overview of the DCO presented by Executive Director Robert Hazen (Carnegie Institution for Science, USA), and an overview of the 2019 DCO Synthesis goals by Marie Edmonds. To conclude the keynotes, Dietmar Müller (EarthByte, University of Sydney, Australia) explained the development of GPlates (www.gplates.org) and how it is serving as the key infrastructure, enabling open access digital plate tectonic reconstructions, while paving the way for a comprehensive digital Earth modeling framework.
Demonstrating the cross-disciplinary goal of the workshop, the first session focused on the links between the biosphere and the deep carbon cycle. Shaunna Morrison (Carnegie Institution for Science, USA) presented on using network analysis to study the co-evolution of the biosphere and the planet’s mineral species in a big data framework. To demonstrate the potential of linking plate tectonic reconstructions and the biosphere, Marshall Bowles (Louisiana Universities Marine Consortium, USA) presented new work on tracking changes in oceanic biomass using post-Pangea plate tectonic reconstructions developed in GPlates.
The second session focused on modeling the deep carbon cycle, and included an opening talk by Sascha Brune (GFZ Potsdam, Germany), who outlined his approach of modeling the evolution of rifts during the Pangea breakup, and accounting for the surprisingly large atmospheric CO2 release, using the GEOCARBSULF carbon box model. Tobias Keller (Stanford University, USA) explained his modeling approach for capturing the behavior of melt migration in mid-oceanic ridge systems, which suggests a significant sub-lithospheric reservoir of carbon-rich melts is trapped during seafloor spreading processes. To conclude the session, the pioneering work of Andrew Merdith (University of Sydney, Australia and University of Lyon, France) was presented on the evolution of Earth’s plate tectonics over the last one billion years in GPlates.
The second day of the workshop covered the various components of the tectonic system driving different aspects of the deep carbon cycle. Emily Mason explained the decarbonation process where magma remobilizes carbon from buried carbonate platforms (and other carbon-rich rocks), thus changing the isotopic signatures of expelled CO2. Sabin Zahirovic considered other CO2 sources from the tectonic system, including Large Igneous Province (LIP) eruptions and subduction activity, as well as the ensuing and longer-term CO2 drawdown during LIP weathering, continental collisions (choking subduction zones, orogenic silicate weathering, etc.), and ophiolite obduction episodes. Artur Ionescu (Babes-Bolyai University, Romania) presented an overview of CO2 and methane sources in ophiolite systems, followed by Ben Tutolo (University of Calgary, Canada), who elaborated on the role of serpentinization reactions at extensional plate boundary settings in modulating CO2 and methane fluxes. In covering perturbations of atmospheric CO2 on geological timescales, Mattia Pistone (University of Lausanne, Switzerland) highlighted the role of mantle plume eruptions in generating LIPs, and how laboratory experiments can help estimate the volume of CO2 released during eruptive phases.
The speaking program concluded with two present-day observational and experiment-based presentations to highlight the fact that all modeling approaches require ground-truthing using real-world data. Ery Hughes (University of Bristol, UK) outlined her recent advances in measuring d13C of basaltic melt inclusions, while João Lages (Università degli Studi di Palermo, Italy) explained the process of measuring in-plume concentrations of volcanic gas species, including CO2, to study time-evolving and spatially -varying volcanic carbon sources and fluxes along subduction zones.
The workshop also included two software demonstrations related to modeling the deep carbon cycle. The first, presented by Sabin Zahirovic and Christopher Alfonso (University of Sydney, Australia), covered how to use GPlates (www.gplates.org) and its new Python interface, called pyGPlates, for modeling and extracting tectonic forcing parameters relevant to the deep carbon cycle (including slab flux, LIP eruptions, ophiolite obduction, etc.). The second demonstration, presented by Amanda Thran (University of Sydney, Australia), provided a comprehensive introduction to modeling surface processes using the open-source community Badlands software (https://github.com/badlands-model/), and in particular, the ability to model reef growth and carbonate platform development in settings with varying terrestrial sediment inputs, water depths, and changing sea levels.
The workshop launched a number of collaborative research projects, which are now underway as part of the DCO Synthesis project titled “The Deep Carbon Cycle through geological time: An interdisciplinary synthesis of the carbon cycle in the Earth’s lithosphere-biosphere system.” The aim of these activities is to generate updated tectonic forcing parameters for use in community carbon box models. These improvements will reveal a clearer picture of carbon exchange between mantle and surface reservoirs resulting from plate tectonics and mantle convection, as well as interactions with the biosphere. This has broad implications for understanding perturbations to the global carbon cycle, and how such changes influence climate change and planetary habitability on geological timescales.
Report and images contributed by Sabin Zahirovic