At a Glance
- MIT geologists have discovered that a clay mineral called smectite found on the seafloor can sequester carbon over millions of years.
- With its accordion-like folds, smectite traps organic carbon and prevents it from being released into the atmosphere as carbon dioxide.
- The carbon-trapping clays are formed through plate tectonics, where rocks brought to the surface by the collision of oceanic and continental plates weather into minerals like smectite.
- Smectite has a global impact, cooling the planet over millions of years and potentially triggering ice ages during major tectonic events.
- These findings have implications for understanding the habitability of planets and suggest a potential application for smectite in offsetting human-induced carbon emissions.
MIT geologists have made a fascinating discovery about a clay mineral called smectite on the seafloor; they have found that smectite can remarkably trap carbon over millions of years. When observed under a microscope, a single grain of smectite resembles the folds of an accordion, which are known to trap organic carbon effectively.
The MIT team has shown that these carbon-trapping clays result from plate tectonics. When oceanic crust collides with a continental plate, rocks are brought to the surface and weathered over time, forming minerals like smectite. Eventually, the clay sediment settles back into the ocean, trapping bits of dead organisms in its folds. This prevents the organic carbon from being consumed by microbes and released into the atmosphere as carbon dioxide.
Over millions of years, smectite can have a global impact by helping to cool the entire planet. Through their research, the scientists have demonstrated that smectite was likely produced after major tectonic events over the past 500 million years. During each event, the clays trapped enough carbon to cool the Earth and trigger subsequent ice ages.
This study is the first to show that plate tectonics can initiate ice ages by producing carbon-trapping smectite. These clays can still be found in certain tectonically active regions today, and the researchers believe that smectite continues to sequester carbon, providing a natural buffer against human-induced climate change, although it acts slowly.
The implications of these unassuming clay minerals extend beyond Earth. According to Joshua Murray, a graduate student at MIT, these minerals have wide-ranging implications for the habitability of planets. There may even be a modern application for these clays in offsetting some of the carbon that humans have released into the atmosphere.
The findings of this study have been published in the journal Nature Geoscience. The research builds upon previous work by the team, which suggested a link between plate tectonics and ice ages. By understanding the role of smectite in carbon sequestration, scientists can gain insights into Earth’s climate history and potentially find ways to mitigate climate change.
References
- Chu, J. & Massachusetts Institute of Technology. (2023, November 30). A mineral produced by plate tectonics has a global cooling effect, study finds. Phys.Org; Massachusetts Institute of Technology. https://phys.org/news/2023-11-mineral-plate-tectonics-global-cooling.html
- Murray, J., & Jagoutz, O. (2023). Palaeozoic cooling modulated by ophiolite weathering through organic carbon preservation. Nature Geoscience, 1–6. https://doi.org/10.1038/s41561-023-01342-9
