In a groundbreaking achievement, scientists using the ocean drilling vessel JOIDES Resolution have penetrated 4,160 feet (1,268 meters) below the Atlantic seabed, reaching the deepest point ever in Earth's mantle rock.
This record-breaking core sample is providing unprecedented insights into the composition and chemical processes of the mantle, Earth's most voluminous layer.
The cylindrical core, obtained from the Atlantis Massif, an underwater mountain in the middle of the Atlantic Ocean, offers a glimpse into the upper mantle's interaction with seawater. These processes are believed to have played a crucial role in the advent of life on Earth billions of years ago.
The mantle, which makes up more than 80% of Earth's volume, is a layer of silicate rock situated between the outer crust and the hot core. Typically, mantle rocks are inaccessible, except at seafloor spreading locations where tectonic plates diverge. The Atlantis Massif, located near the mid-Atlantic Ridge, is one such site where mantle rock is exposed on the seafloor.
From April to June 2023, researchers drilled into the mantle rock about 2,800 feet (850 meters) beneath the ocean surface. They recovered a core sample that is 2,907 feet (886 meters) long, comprising more than 70% of the drilled rock. This achievement surpasses previous attempts, which penetrated no deeper than 656 feet (200 meters) with low rock recovery.
"The recovery is record-breaking," said Johan Lissenberg, a geologist at Cardiff University and lead author of the study published in Science. "Previously, we have been largely limited to mantle samples dredged from the seafloor."
The core sample, with a diameter of about 2.5 inches (6.5 cm), revealed how the mineral olivine had reacted with seawater at various temperatures. This reaction releases hydrogen, forming compounds like methane that support microbial life, a key hypothesis for the origin of life on Earth.
"Our recovery of mantle rocks enables us to study these reactions in great detail and across a range of temperatures," Lissenberg said. The drill site, located near the Lost City Hydrothermal Field, an area with hydrothermal vents spewing super-heated water, is thought to be representative of the mantle rock beneath these vents.
"One suggestion for the origin of life on Earth is that it could have happened in an environment similar to Lost City," said Andrew McCaig, a geologist and study co-author from the University of Leeds.
Preliminary analysis of the core sample has revealed a more extensive history of melting than expected, with the mineral orthopyroxene showing a wide range of abundance. This discovery relates to the flow of melt through the upper mantle, which rises beneath spreading plates and migrates towards the surface to feed volcanoes.
The core sample continues to be analyzed, promising further revelations about Earth's deep interior and its role in the planet's geological and biological history.
Source: India Today