The volcanoes that created oil out of dinosaur bones

Grass in the foreground and mountains in the background. Photo.Green hills of sprawling grass. Snow-capped mountains and volcanoes as far as the eye can see. A sky that within seconds turns black in the darkest thunderstorm. And condors circulating high above our tent, looking for carcasses. We are in the dinosaur kingdom, the Neuquén province in western Argentina, in the foothills of the Andes. We are here to examine the traces of volcanic activity. Events that took place millions of years ago, and that formed oil where no oil should be formed.

Neuquén is Argentina's most important oil field. Thousands of pumps hungrily devour oil and gas from the depth of the Earth’s crust. The oil comes from sedimentary rocks that were deposited during the time of the dinosaurs. Therefore, the area is also famous for its many dinosaur findings. For example, the giant carnivorous dinosaur Giganotosaurus was found here.

Volcanoes creating oil
However, we are not here for the dinosaurs, but for the many volcanoes. In my research I study how magma moves through the Earth's crust and how magma is stored in so-called magma chambers. The very unique thing about the volcanoes of Neuquén is that it is because of them, or the magma they produced, that oil could be created here. Because for oil to be produced you need three different ingredients; organic material buried in an anaerobic environment, high pressure and heat. In the sediments of Neuquén there is plenty of organic material, including all the dinosaur bones that are buried here. But these sediments are not actually buried sufficiently deep to create pressures and temperatures high enough to make the material turn into oil. But the volcanoes help. The magma in the volcanic interiors raised the temperature in the ground, and in that way enabled the formation of oil.

The same phenomenon has been known to occur in the rocks beneath the North Sea, but to investigate it there requires geophysical methods. Here in Argentina, we can climb the mountains and look into the actual magma chambers ourselves.

Oozing oil in magma chambers
The project is led by Olivier Galland, researcher at the University of Oslo, and partly funded by the Norwegian Research Council and Argentina's governmental oil company, YPF. The project involves dozens of researchers from Norway, Argentina, Sweden, France and Britain. I went here along with two PhD-students, Octavio Palma from Argentina and Tobias Schmiedel from the University of Oslo, for a closer look at the very special conditions that the volcanoes in Neuquén created for the formation of oil.

Because the oil reservoirs in Neuquén are kind of unique. Once the oil had been produced it was flowing up and into the widespread network of cracks in the solidified magma chambers that had intruded into the sedimentary layers. And even today, oil is extracted from such magma chambers. In the vicinity of the active Payun vulcano, for example, oil from an old magma chamber is extracted from a depth of just a few thousand meters.

Our trip started with a one-week excursion, followed by a week of field work. During the excursion we climbed an active volcano, examined sedimentary layers with millions of fossils that were transformed into oil elsewhere, and visited a mine where bitumen, a viscous form of oil is extracted from cracks 5 meters wide and several thousand metres long. 

A mountain, a hand holding a black stone and grassy land in mountainous areas. Photo.
Above: On our journey we climbed Tromen, an active volcanoe. Below left: In cracks 5 meter wide and several thousands meters long, bitumen, a kind of viscous oil can be extracted. Below right : A hike in the foothills of the Andes. Photo: Steffi Burchardt.

After the excursion several researchers stayed in small groups to explore different areas closer. Together with the PhD-students I took a closer look at the Chachahuén volcano, which also has a solidified magma chamber. The volcano was active some 6-7 million years ago and is now very eroded. Today its magma chamber looks like a steep mountain, reaching towards the Southamerican sky like a giant cathedral. The magma chamber is now at the surface of the earth, allowing us to climb into its very heart. Together we were able to investigate the fracture network in it in detail, and went home with a much better understanding of ​​how the oil in Neuquén can be stored in such solidified magma chambers.

clay huts with mountains in the background, a clay oven and a fireplace. Photo.
Above: The huts at the puesto where we stayed were made out of mud, cardboard tetrapacks. Below: Enrique prepared delicious food for us every day. Photographer: Steffi Burchardt. 

An adventure amongst cougars, volcanoes and tetra pack
During my years as a researcher I have worked extensively out in the field, on different continents and in many different places. But this trip has definitely been my most adventurous field work ever. Not because of the amazing geology, but because of the circumstances. Chachahuén is situated about three hours’ drive from the nearest town. Getting there is very hard. Our car was shaking heavily on the poor road when we were driving there. And on one occasion, we had ostriches running in front of the car, racing with us.

In the mountains around Chachahuén there are not many people. Only seven humans live here, under free but primitive conditions. They live in so-called Puestos, small farms, together with their goats, cows and horses. During our fieldwork we put up our tent at one of these Puestos, which really only consisted of a few huts built out of mud. Our friendly hosts Maria and Enrique used an open fire to cook food, in a hut built of twigs, cardboard and tetrapacks. On the farm there is no running water, it has to be carried from the mountains with the help of horses. A small wind turbine produced enough electricity to charge their only flashlight.

Generosity, kindness and attacking cougars
Despite their poverty, Maria and Enrique are among the most generous and kind people I have ever met. They allowed us to stay for a whole week, and every day they prepared delicious food out of the groceries we brought from town. In return for their great hospitality, we brought food to all the families in Chachahuén, and they were very grateful for the fruit, sugar and flour. Their regular menu usually consists of goat meat, which we too ate a lot during our stay. Except for the first evening, when we were given something completely different. The meat of the guanaco, a wild llama, which Enrique had shot before we came. I was also told that people in Chachahuén sometimes eat cougar meat. Here there are many cougars, and sometimes they kill the goats, even people. The cougar is a protected species even in Argentina, but for Enrique and his family a meeting with a cougar is a question about life or death. Therefore they explained to us how to best kill an attacking cougar. A knowledge I do not want to be forced to use next time I go there.

Dwarf armadillos and mountain landscapes. Photo.
Left: This cute litte guy is a dwarf armadillo. Right: On top of a magma chamber. Photographer: Steffi Burchardt. 

Because I will be back. The adventure in Argentina has just begun. During this first field season we found many interesting places we will investigate further during the project. And in March, we will return to the volcanoes that created oil out of dinosaur bones.

Text: Steffi Burchardt & Katarina Sundberg
Photo: Steffi Burchardt