Orogen Dynamics Team takes a peek into the bowels of the Earth

Scientists can discover these particular forms because the previously subducted oceanic plate fragments lift up to the surface during orogeny. Orogens, however, keep eroding, revealing metamorphic rocks, i.e. formed exactly under the conditions of extreme pressure and temperature. The members of the Orogen Dynamics Team search for those even in the most harsh and secluded areas of the Arctic: in Spitsbergen, Ellesmere Island, and Greenland.

Mysterious eclogites

When geologists stumble upon an interesting specimen, they immediately subject it to meticulous lab tests. The process of such investigations is illustrated by the example of a discovery made in the Scandinavian Mountains by Michał Bakuła (Dr, Polish Academy of Sciences [PAN]) and Christopher Barnes (Dr, PAN) then Prof. Majka’s doctoral students at the AGH UST. They had encountered rocks that they have classified as eclogites. This type of rock is characterised by its ability to accumulate large volumes of hydrous minerals, i.e. containing water in its chemical composition. However, in this case, the fluid has completely evaporated at some point.

The researchers have also noted that the rock has undergone brittle deformation, which normally should not occur at such depths under a relatively high temperature, that is, in conditions in which the rocks show elastic properties. ‘At the beginning, we haven’t ruled out the possibility that it could have occurred later, during the unearthing. However, using X-ray microtomography, we’ve determined that the fractures had been filled with high-pressure phases. This means that the fractures must have originated under extremely high pressure and considerably high temperature, and therefore very deep underground’, says the leader of the Orogen Dynamics Team.

Ultimately, the geologists have come to the conclusion that the dehydrated minerals trapped in the rock were lawsonite and glaucophane. When, after subduction, it has been subjected to high temperature, the minerals started to release water. This caused an increase in the pressure of the fluid inside the rock and, as a result, its rapid release (hydrofracturing) and blowing apart.

‘We have probably come across a hypocentre of a massive seismic event or at least a spot very close to one. A similar phenomenon caused an earthquake in Chiapas, Mexico, in 2017, where the hypocentre of the quake was also located in the area of a subducting plate. Normally, we cannot observe such events, unlike near the famous San Andreas fault, where hypocentres occur quite shallow. For me, this is the most exciting discovery of the last three years‘, highlights Professor Majka.

The origins of Orogen Dynamics Team

The origins of the Orogen Dynamics Team can be traced back to 2015, when Professor Majka created the team at the AGH UST, implementing a SONATA BIS grant. The geologist had already acquired substantial scientific experience. He graduated from the AGH University of Science and Technology, where he could carry out his research in the Arctic side by side with Professor Maciej Manecki and Dr (Eng.) Jerzy Czerny, and under the supervision of Professor Andrzej Manecki. Having defended his doctoral dissertation, he was invited to work at the Slovak Academy of Sciences, where his research focus was directed primarily on the Carpathians.

Later, he worked at the Uppsala University. ‘This was a return to the Arctic because the person who invited me there was Professor David Gee – a living legend of Arctic research. I learned from him and other people I met. Around 2014, time and opportunities presented themselves to set my foot back at my Alma Mater and build this team‘, recounts Professor Majka.

At first, the group employed only a few people; now, there are more than a dozen – affiliated not only to the AGH University of Science and Technology, but also to other universities and research institutions. An important part of the team is its continued relationship with the Uppsala University, which, in addition to the AGH UST, is another place of work of Professor Majka and – as he himself claims – an outpost of Orogen Dynamics Team. All doctoral students who belong to the team receive double diplomas, and independent scholars obtain the status of a visiting researcher in Sweden. The Swedish law grants the former the privilege of supervising MA students, which constitutes a valuable asset to their academic CVs.

‘The team connects people of various ages, both those for whom the AGH UST is the first employer and those affiliated to other Polish and international research centres. We have people from different cultural backgrounds and of multifarious nationalities. We’re well-balanced in terms of age, sex, and experience’, the team leader emphasises.

Professor Majka adds that the group’s structure is open and that each member is expected to help others. This applies specifically to those who are significantly advanced in their academic careers.

‘Sometimes, in some circles, the fact that we all address each other by our first names, not paying attention to our titles or academic degrees, evokes bewilderment. This is insignificant. What is important is that people respect each other and have this natural feeling that, although certain situations require due honours, in the end, we are all a group of friends. If people feel good around one another, they work well with each other’, says Professor Majka, revealing his recipe for successful team management.

New projects: research in the Pieniny Klippen Belt and discovery of the secrets of quartz

Soon, members of the Orogen Dynamics Team affiliated to the Faculty of Geology, Geophysics, and Environmental Protection will begin working on three new projects funded by the National Science Centre. One of them will be coordinated by Professor Majka. The chances are that it will formulate a new evolutionary model for the closure of the Alpine Tethys Ocean and update the knowledge on the creation of the Western Carpathians.

The scholars focus mainly on the Pieniny Klippen Belt, which, according to geologists, is a surface expression of a much deeper structure, probably reaching down to the Earth’s mantle. The researchers think that this is the so-called ‘suture’, i.e. a point of contact between two continental plates, previously separated by an oceanic plate. Usually, in places like that, the remnants of the latter can be found alongside high-pressure metamorphic rock. However, the area under scrutiny lacks such formations. Therefore, the scientists wonder whether they had been buried very deep, eroded, or lost in some other way.

To find the answer, the scholars plan to carry out far-reaching petrological research. ‘When we examine the ‘detritus’, that is, samples of eroded rocks and minerals that can withstand erosion and weathering, we see parts that fit. Many people had worked on it; however, we want to take this a step further. We plan to investigate the conditions under which some of these minerals were created and to date them. If we receive pressure and temperature conditions, as well as age, that converge with what we know about the period of subduction and collision processes, our hypotheses shall be verified’, explains Prof. Majka.

The petrological analyses will be supplemented with geophysical studies, the results of which will include imaging of the deep crust and shallow mantle within and across the Western Carpathians, that is, from Krakow (Poland) to Eger (Hungary).

New knowledge on quartz and its high-pressure polymorph – coesite can be brought about by the project of Dr (Eng.) Karolina Kośmińska. The mineral commonly occurs in metamorphic rocks; however, it still has a bunch of secrets for geologists to uncover. To find out more about it, the scholars want to subject natural specimens from the Alps, Spitsbergen, and Scandinavia to a wide spectrum of petrological studies. They will also investigate samples that they will prepare themselves under controlled lab conditions.

While at it, the scientists will also check whether the imaging technique based on acoustic impedance, previously used to examine sedimentary rocks, will be useful in the case of metamorphic rocks. If so, they will attempt to calibrate a new tool for geothermobarometry. The investigations will be carried out in cooperation with Professor Tadeusz Stępiński from the Faculty of Mechanical Engineering and Robotics.

Estimation of the volume of carbon dioxide trapped in the lithosphere

In addition to answering the questions about Earth’s history, the project of Dr Alessia Borghini, who arrived at the AGH UST from the University of Potsdam, can provide a solid base for considerations about the future of our planet.

Dr Borghini, as part of a project she leads, will investigate the deep cycle of volatiles (e.g. water, carbon dioxide, chlorine, fluorine, bromine, and iodine) that occurs during the subduction of a continental plate, when two continents collide. The subducted plate, under high pressure and temperature, can undergo the processes of dehydration and partial melting, releasing volatiles into the Earth’s mantle.

To investigate this process, the geologist plans to analyse rocks from the mantle that contain the minerals with the capacity to accumulate substances she is interested in. The samples will be collected in the Scandinavian Caledonides, the Bohemian Massif, and the Eastern Alps. Based on the samples, the researcher intends to describe a model of their cycle during orogenic processes during which the aforementioned mountains came about, that is, for a considerable portion of the Phanerozoic (between 420 and 90 million years ago).

The results can provide a better understanding of climate change on Earth. The volatiles released into the Earth’s mantle during a subduction of an oceanic plate are partially emitted into the atmosphere during volcanic processes, whereas in the case of a continental subduction, this process does not occur and the aforementioned compounds are probably stored within the mantle, including carbon dioxide, which is one of the key actors in global warming.

Although the former case has been described well numerically by scientists, the latter still has a few question marks. ‘If the scientists dealing with climate change wanted to access data on how long it takes for carbon or other elements to be recycled, they could not do that because there are no such data or they are incomplete. Dr Borghini has already performed quite advanced investigations, certain ideas in this field, and a paper pending review in the renowned Sience journal. Now, she wants to take this extra step and continue her research with our team, as the beneficiary of a prestigious Marie Skłodowska-Curie Actions EU programme’, says Prof. Majka.