Studying rocks is like reading a book, opening doors to ancient and little-known stories. It was in this spirit that Frieder Klein, a postdoctoral fellow in the Department of Marine Chemistry and Geochemistry at Woods Hole Oceanographic Institution (WHOI), and his team studied rock samples taken from the vicinity of Saint-Pierre and Saint-Paul. Located on the Saint-Paul oceanic transform fault, approximately 500 km off the coast of Brazil. Their work opens up a previously unexplored page in the geological carbon cycle.
An unexpected carbon reservoir
Transformation faults, areas where tectonic plates move sideways relative to each other, constitute one of the three major plate boundaries on Earth. Measuring about 48,000 km in length, they were long ignored in the study of the carbon cycle and considered of little interest due to their low magmatic activity. However, the work of Klein and his colleagues shows that these zones may represent significant carbon sinkdue to carbonization of mantle rocks caused by magmatic degassing and magma entrainment.
An underestimated influence on the Earth’s climate
Although CO2 emissions from transform faults are minimal compared to anthropogenic emissions, they played a dominant role in regulating Earth’s climate on geological time scales before human activity took over. This discovery highlights the importance of understanding natural climate variations in understanding current human-caused climate change.
Innovative research method
The study is based on an analysis of the formation of steatite and other magnesite-containing complexes during the mineral carbonization of peridotite in the Saint-Paul fault, which revealed the complex process of CO2 capture by mantle rocks. These results were obtained using vehicles occupied by people during an expedition in 2017, marking the realization of a hypothesis formulated by researchers twelve years earlier.
Funding needed for research
The project received support from the Dalio Ocean Initiative, the WHOI Independent Research and Development Program, and the National Science Foundation, highlighting the importance of collaboration and funding in advancing scientific knowledge.
Woods Hole Oceanographic Institution: Leader in Marine Research
WHOI, a private, not-for-profit institution located on Cape Cod, Massachusetts, stands out for its interdisciplinary approach and advanced capabilities in underwater robotics, making significant contributions to ocean research and development.
Better understanding of the carbon cycle
This study makes a major contribution to our understanding of the geologic carbon cycle by highlighting the critical role of oceanic transform faults. This opens the way to new research needed to understand the natural mechanisms that control our climate and, as a result, to address the challenges of human-caused climate change.
Source de l'article : https://doi.org/10.1073/pnas.2315662121