Scientists have successfully retrieved a significant length of mantle rocks, marking the first time such materials have been collected. These rocks, from the layer beneath the Earth’s crust, hold valuable insights into the mantle’s influence on the emergence of life, volcanic activity when it melts, and the global cycles of essential elements like carbon and hydrogen.
Scientists have successfully retrieved a significant length of mantle rocks, marking the first time such materials have been collected.
The recovered rocks will aid in understanding how the mantle contributes to the beginnings of life on Earth, the volcanic processes that occur from its melting, and its role in the global cycles of key elements like carbon and hydrogen, as explained by the research team.
During the Spring 2023 expedition dubbed “Building Blocks of Life, Atlantis Massif,” a remarkable 1,268 meters of nearly continuous mantle rock was obtained from a “tectonic window.” This area on the seafloor, located along the Mid-Atlantic Ridge, exposed mantle rocks, allowing for their exploration via the ocean drilling vessel JOIDES Resolution.
The achievement is a record-breaking milestone, following efforts that span back to the early 1960s, and was spearheaded by the International Ocean Discovery Program, which comprises over 20 countries. This collaborative initiative is focused on extracting cores—cylindrical sediment and rock samples—from the ocean floor in an effort to piece together Earth’s history.
Since the collection, the expedition team has been working on cataloging the mantle rocks to explore their composition, structure, and significance.
Their research, published in the journal Science, indicates that the history of melting in the sampled rocks is more extensive than anticipated.
Lead author Professor Johan Lissenberg from Cardiff University commented, “The recovery of the rocks last year was a significant milestone in Earth sciences. More importantly, their cores may provide insights into the composition and evolution of our planet.”
“Our study starts to analyze the mantle’s composition by documenting the minerals present in the recovered rocks, alongside their chemical properties.”
“We found results that were quite different from our expectations. The mineral pyroxene appears in much lower amounts, while magnesium levels are notably high, pointing to greater melting than we initially predicted.”
This melting process took place as the mantle ascended from deeper layers of Earth toward the surface.
Further analysis of this process could greatly enhance our understanding of magma formation and its contribution to volcanic activity, according to the researchers.
“We also discovered pathways that show how melt moves through the mantle, allowing us to trace the journey of magma from its formation to its ascent to the Earth’s surface.
“This discovery is crucial as it sheds light on how mantle melting occurs and provides magma for volcanoes, particularly those underwater, which represent the majority of Earth’s volcanic activity. Accessing these mantle rocks enables us to connect the dots between volcanoes and their magma sources.”
The research also includes initial findings on how olivine, a prevalent mineral in mantle rocks, interacts with seawater, resulting in various chemical reactions that create hydrogen and other molecules that could support life.
Scientists propose that this process may have been fundamental to the emergence of life on Earth.
Dr. Susan Q Lang, an associate scientist in Geology and Geophysics at the Woods Hole Oceanographic Institution, who co-led the expedition, noted, “The rocks we found resemble those present on early Earth more closely than the more common continental rocks we see today.”
“Studying these rocks provides us a vital glimpse into the chemical and physical environments of early Earth, which may have consistently offered fuel and favorable conditions over vast time periods that supported the first forms of life.”
The international team of over 30 scientists involved in the JOIDES Resolution expedition will continue their investigations on the acquired drill cores to explore a variety of scientific questions.
Dr. Andrew McCaig, Associate Professor at the University of Leeds and a co-leader of Expedition 399, remarked, “Everyone associated with Expedition 399, beginning with the proposal in 2018, has reason to be proud of the findings discussed in this publication. The new deep hole we’ve created will serve as a reference point for decades in fields ranging from melting processes in the mantle to organic geochemistry. All data from the expedition will be accessible, setting a standard for international scientific collaboration.”
