This animation illustrates absolute plate motions and plate boundary evolution of Gondwanaland during its breakup and tectonic plates in the Pacific ocean basin. The paleo-age-area distribution of the ocean floor is shown with red/orange colours indicating young ocean floor (0-50 million years) and cool colours (yellow/green) relatively old ocean floor (between 50 and 100 million years old) (plate model from Müller et al, 2016). The red-white-blue band along subduction zones indicates the plate convergence speed. The small dots along the western South American margin which appear through time correspond to porphyry copper-gold deposits. In a paper published in Tectonics, Butterworth et al. (2016) combined plate tectonic parameters like convergence speed, obliquity and age of the subducting crust with machine learning methods to determine key tectonic parameters which favor the formation of porphyry copper-gold deposits
Making Magic Happen
In 2016, the EarthByte group, based in the School of Geosciences at the University of Sydney, created a visualization tool and model to measure the interactions of arc volcanism with buried carbonate platforms in deep time. The new workflow tools, which are available to the DCO community, enable scientists to approximate paleo-atmospheric CO2 flux within a plate tectonic framework over hundreds of millions of years. The models go back as far as the Devonian Period, a time when the megacontinent Gondwana occupied most of the Southern Hemisphere.
In the words of project leader, Dietmar Müller, “What we have created is a virtual plate tectonic deep carbon laboratory – it revolutionizes our ability to understand mantle-crust-atmosphere interactions in deep time.”
It was a huge undertaking, requiring the design of a script-based toolkit to extract global data from plate models such as global subduction zone lengths and ocean crust CO2 content. The project leveraged expertise from a network of researchers from the EarthByte group, the California Institute of Technology; School of Earth Sciences, University of Melbourne; Department of Earth Sciences, Rice University; and the Department of Earth Sciences, University of Oxford. The work was undertaken as part of a DCO grant “Toward a 4D Planetary Carbon Model,” supported by the Alfred P. Sloan Foundation.
Dietmar Müller spearheaded the EarthByte group effort, and in under two years the group managed to create tools that link paleogeography, climate and deep carbon with tectonic models. In addition, Müller and his team have created a treasure trove of outreach material to engage scientists and the public in deep-time and deep-Earth carbon science.
The first is a DCO project blog on earthbyte.org that describes the methodologies, workflows, models and animations produced during the project. The data sets produced for this project are available publicly on the research data repository Zenodo, which is linked to their project page on the DCO data portal. The project team will continue developing the tools and workflows further in the future and will continue to update them on the Zenodo repository and DCO Data Portal with community input. A paper will be published later this year entitled, “Arc volcanism, carbonate platform evolution and paleo-CO2: Components and interactions in the deep carbon cycle.”
Müller sums up the project’s achievements as: "We have created some simple, extendable tools that enables scientists and non-scientists to experiment with how tectonic forcing has influenced the climate in Earth's past. In addition, we are now linking singal processing tools like wavelet analysis into these workflows. They allow us to analyse objectively during which time periods and at which cyclicities subduction-driven cycles of carbon emissions – or sinks – correlate with geologically mapped CO2 cycles through deep time."
Here’s a look at some of the products developed over the two-year period that are available to the DCO community, as well as the general public:
Compiled and digitized existing published data including the paleo-CO2 proxy record, paleo slab flux estimates from subduction zone lengths, rates of volcanic CO2 degassing and feedback-based models of paleo-CO2.
Created an evolving model carbonate platform geometries in GIS and GPlates compatible file formats.
Created a toolbox that is able to analyze subduction zone data, including: compute subduction zone lengths; determine total lengths that interact with carbonate platforms or other mappable features; classify continental vs. intra-oceanic arc subduction zones based on continental polygons which can be adapted to any continental feature.
Additionally, the scripts in the toolbox enable oceanic upper-crust CO2 reservoir modeling by: tracking and computing statistics of CO2 content, age and thickness of subducting oceanic crust; and generating time-dependent grids of predicted CO2 content in the upper oceanic crust.
Generated sediment thickness grids of the ocean floor based on Müller et al. (2016), which may be used as an indicator of the subduction flux of CO².
Convened a Deep Carbon Modeling Workshop at the end of August 2016 to discuss project results and collaborating on future projects with other geoscientists from in and around Sydney.
From the outset, the EarthByte team consciously designed tools that could be applied and used by their peers. Their oceanic crust and subduction zone analysis tools, for example, are very versatile and adaptable to test a variety of hypotheses. The subduction zone analysis scripts can take any GPlates plate reconstruction model with resolved topologies to quantify the length of subduction zones that intersect with any crustal feature of choice. Similarly, their crustal analysis tool measures any property of the oceanic crust as it subducts along the entire length of subduction zones through time.
How to Get Involved
Curious about how these tools might expand your research? Learn more here
Zahirovic, S., Matthews, K.J., Flament, N., Müller, R.D., Hill, K.C., Seton, M. and Gurnis, M., (2016), Tectonic evolution and deep mantle structure of the eastern Tethys since the latest Jurassic, Earth Science Reviews, doi: 10.1016/j.earscirev.2016.09.005.
Zahirovic, S., N. Flament, R. D. Müller, M. Seton, and M. Gurnis (2016), Large fluctuations of shallow seas in low-lying Southeast Asia driven by mantle flow, Geochemistry, Geophysics, Geosystems, doi: 10.1002/2016GC006434.