By Suzette Timmerman

The Deep Carbon Observatory (DCO; https://deepcarbon.net/) is an organization that investigates the carbon cycle. Researchers from all over the world are linked to this organization in four communities: extreme physics and chemistry, reservoirs and fluxes, deep energy, and deep life. We explore the behavior of carbon at extreme pressure and temperature conditions, how much carbon there is in which reservoirs and how it moves, how it changed over time, and the extreme conditions of life.

I was lucky to have the opportunity to attend the amazing summer school that the DCO organized in Yellowstone!  About 35 Early career scientists of different fields were present; microbiologists, biochemists, seismologists, volcanologists, experimental petrologists, and diamond people. In 5.5 days we learned not only a lot about Yellowstone, but also how important it is to look at the larger scale systems and to use an interdisciplinary approach. It was also a great chance to get to know the people whom I will be working with for the rest of my life and is a good start for any future collaborations.

We started with an icebreaker party on Saturday night. Everyone had a card with a picture on it, and so we had many conversations on the meaning of the pictures, while eating pizza and chicken. The next morning, we left early for our first field day in Yellowstone National Park. The Yellowstone hotspot created many volcanic events (starting at 17 Ma), including the 2.08, 1.3, and 0.64 Ma volcanic eruptions and caldera forming events of Yellowstone itself. It was characterized by three phases. From 17 to 4 Ma widely dispersed volcanism is related to the initial hit of the plume head with the lithosphere, from 14 to 10 Ma there is a transition from plume head to tail that is shown by frequent large volume, high temperature rhyolites, and from 10 to 2 Ma volcanism is caused by the tail of the plume resulting in large ignimbrite eruptions.

The Yellowstone area is still very active, both seismically and geothermally. There are many geysers (> 600), hot springs (> 14000 !!), and vents. The caldera is about 55 times 72 km square.

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The caldera stretches all the way to the mountains in the distance of this photograph (this is the short side of 55 km)

Along with fractures, the hydrothermal activity has also weakened some of the rocks, making it easier to erode. This is well seen by the location of the canyon of the Lower Falls. Different colours are evidence of the hydrothermal activity.

We then continued to see breccia deposits of the Mary Bay hydrothermal explosion. The Mary Bay crater formed 13000 years ago and has a area of 2000×1300 m² and a volume of 20×10⁶ m³. The crater is in the lake and bathymetry showed that it has many small craters, hydrothermal vents and domes on the crater floor.

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Deposits of the hydrothermal explosion of the Mary Bay crater

The second field day we started at Grand Prismatic and Exselsior hot springs, to have a look at the microbes. The night before we learned about really cool pink protobacteria, white-yellow-green oxygenic phototroph cyanobacteria, green chloroflexis bacteria that provide the structure for the microbial mats, heterotroph moss green thermus aquatus bacteria, and also about Archaea and Eukaryota. The blue colour of the grand Prismatic hotspring has a boiling point of 93 °C and the colour is caused by the reflection of light. Outwards the temperature decreases and there are a lot of cyanobacteria causing the yellow and orange colours. Spectacular was also the eruption of Old Faithfull Geyser, that happens roughly every 90 minutes.

We continued our walk around the Old Faithfull area to see more geysers and microbial life. Some amazing examples are shown below.

At the end of each day we had dinner at the Chico Hot Springs resort. Company, food, swimming pool were all wonderful.

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Dinner at the Chico Hot Springs Resort

Subsequently we had a day in the convention center at the resort. We had several inspiring talks and were able to show our research as well in two poster sessions. On the Wednesday we had another day in the field. I was part of the great team Carbon, as you can see below.

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Team Carbon

In teams we learned several sampling techniques along the Bear Creek just outside Yellowstone park. We measured CO₂, H₂S, and SO₂ concentrations and CO₂ fluxes with a MultiGAS (see below), we sampled water and gases with a Giggenbach bottle, in a grid we measured CO₂ concentrations and fluxes with a Gas Accumulation chamber and took a sample of the CO₂ respiration of the vegetation that we analysed for carbon isotope composition in the evening, looked at microbes and some nice rock outcrops. It was cool that when all the groups combined their data we could see there was an area with a higher CO₂ flux and heavier carbon isotope compositions than air. This was one of the best experiences; using some new instruments, working together and obtaining an understanding of an area with results in such a short time.

In the afternoon we went to Mammoth Basin (see below). These are travertine deposits, with orange colours (microbes and iron) and white colours. Similar to forensic science with the idea of isotopic values reflecting the area you live in and the what you eat and drink, the development and type of microbes is also ‘you are what you eat’, and is dependent on the host rock, mineralogy, fluid flow paths, water-rock interaction and time. Prior to the development of hydrothermal activity, trees get white socks (see in the picture as well) and die.

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Mammoth basin (travertine deposits)

We had a last day at the resort discussing the results obtained at Bear Creek, thinking about microbes, the use of social media to promote research (I have now a Twitter account!), and mineral evolution.

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Group photo by Katie Pratt

I have had a surreal great time and met amazing people, that will hopefully lead to many collaborations in the future. Many thanks to the DCO for organizing and giving me this opportunity, and all the instructors and early career scientists for a wonderful time and learning experience.