2024-01-14 05:00:00
A group of geology researchers from Conicet studied how the southern end of the Southern Cone of America was formed, the region that is currently known as Patagonia. This is key knowledge for scientific development applied to deposits with great economic potential, such as Vaca Muerta.
There has always been a debate regarding the origin of the region: Was it a separate continent that at some point joined South America or was it always united?
Through a study that was published in the journal Gondwana Research, researchers came to the conclusion that Patagonia was formed gradually from the very margins of the ancient supercontinent Gondwana, through the rise of material from the Earth’s mantle. It would have had an “origin on site”.
“The formation process of Patagonia began in the last 600 million years and is still occurring. If we move west we reach the Andes Mountains, where continental crust is currently being generated. These processes, which from time to time involve an earthquake or some volcanic eruptions, gradually make the crust grow over hundreds of millions of years,” he explained to RÍO NEGRO Diary Emiliano Rendageologist participating in the project and professor at the National University of Río Negro (UNRN).
The research managed to refute a hypothesis installed within the field of Geology: the formation “from the situation”. According to these positions – widely debated since the eighties -, Patagonia would have been a drifting continent that collided 250 million years ago with the southwestern margin of the great continental block that integrated South America, Africa, Australia, Antarctica, Oceania and India.
To arrive at the new evidence, researchers from the University of Buenos Aires (UBA) and the National University of Río Negro (UNRN) carried out field work in ancient mountain formations in the provinces of Neuquén, Río Negro and Chubut. Through mapping, sample collection, chemical and microscopic analysis, they were able to determine the age and depth where the rocks were.
“What we do is microscope analysis to see what types of rocks they are and what origin they have. We also separate certain minerals that allow us to know the age of the geological events and how deep they have been. This allows us to know if that rock was part of an ancient volcanic arc and if it was five or ten or 30 kilometers deep. We also do chemical analyzes to see its possible origin, whether it is volcanic lava or an ancient sediment from a river,” he said in dialogue with RÍO NEGRO Diary Sebastian Oriolofirst author of the research and member of the Institute of Basic Applied and Environmental Geosciences of Buenos Aires (IGEBA).
These data allowed the creation of scientific models that verified that the Patagonian region was formed gradually from north to south. In the extreme northeast of Río Negro you can find the oldest rock formations and in the southwest of Tierra del Fuego and Chile, the youngest.
Why do you investigate the origin of the region?
This work, which was supported by National Geographic– aimed to address a basic scientific problem. The key to this type of knowledge lies in its importance for applied knowledge, that is, it allows for further investigation of more specific structures, such as mineral or fossil exploitation areas.
“These basic science work approaches have a direct transfer to applications on Vaca Muerta or mineral deposits. In the same way that one has a methodological approach to understand the thermal evolution of ancient rocks, it can be applied with the rocks of the Neuquén basin to control the maturity of the deposits,” Oriolo detailed regarding the transfer of study methodologies.
The researchers observe that the early evolution of the Patagonian continental shelf has a direct control on the evolution of the deposits. These mineral deposits date back approximately 170 million years and began to develop once the crust formation processes were already “stabilized.”
“The movements or generation cycles of ancient crust are comparable to the structure of a house or a building. There are places where faults occur in the crust, and once the formation process is complete, these faults – known as the preferential orientation of some planes of weakness when deforming – are recorded in the crust. Subsequently, millions of years later, places known as basins are generated in these sites, which is where sediments are deposited,” Renda said.
According to the researcher, these ancient faults delimit the direction in which the basins, or depressed areas, are filled. “There are materials that have a northwest-southeast orientation, and that in turn controls the sites with the most deposits. And it can determine where more gas is generated, where more oil. Although these elements have different formation processes, they are always related to those ancient areas where fluids are channeled from very deep,” he added.
For his part, Oriolo explained that although the deposits are “anomalies”, to analyze them in detail an understanding of the entire region where they are located is required. “If it is known that the evolution of Patagonia is more or less continuous with the rest of South America, it is expected that during this joint evolution of the deposits there will be similarities. “These models provide a regional framework to start looking for or understanding things in detail,” he added.
Science that pays
The results of the study They provide new knowledge that is highly valued by mining, oil and gas companies. due to their need to understand the background of their areas of exploitation. This is when the synergy between science and economics originates.
“We work a lot in linking with companies providing services, that is, we do a lot of knowledge transfer. Sometimes the issue of productivity is discussed and the truth is that this allows us to generate our own funds, both for Conicet and for the institutes where we work. For example, where I am currently we had more self-generated budget in 2023 than contributed by the State,” Oriolo detailed.
The researcher even highlights that many research theses are the result of this work as advisors in this type of company.
How the Vaca Muerta site appeared
The project on the origin of Patagonia encompasses other parallel investigations, linked in many cases to postgraduate theses by the team’s researchers. These are characterized by being more local in nature, due to the technical impossibility of covering large territories.
One of the works that is currently in development addresses the late evolution and history of the Neuquén basin. This area has an origin from 170 million years ago, when it began to form in the Late Triassic to the Early Cretaceous.
“What interests us is to see the temperature, which has a central role for organic matter. The idea is to study the earliest evolution from a thermal point of view during the opening of the basin,” Oriolo stated regarding the objectives of the project under study.
In addition to Vaca Muerta, They are carrying out similar research in other sites in Patagonia, especially in the province of Santa Cruz. These areas, somewhat less explored by the scientific community, are considered the youngest in the Patagonian region.
Finally, the working group will publish new publications and compilations linked to the origin in the coming months on site from Patagonia. Above all, it will focus on the discussion with the existing bibliography in the last 40 years. In future work, researchers hope to investigate the Malvinas Islands and their possible joint formation with the continental shelf of the Southern Cone.
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