Scientists just found a new type of rock under the Pacific Ocean

The new basalt has just fallen. An international team of scientists drilled nearly a mile into the Pacific ocean floor and mined a variety of chemically and mineralogically different volcanic rock from any kind previously known.

The team examined a 49-million-year-old stone outcrop that formed just a few million years after the Ring of Fire, that famous half-moon of volcanic activity that lines the Pacific Rim. . During the first millions of years after its ignition, the ring burned with a superheated intensity that the team said formed a unique type of stone.

They traced this evidence of Earth’s history nearly 5 miles below the ocean’s surface. Their analysis suggests that the fires that forged the rock were hotter and more expansive than previously thought. Their results were published last week in Nature Communications.

“The rocks we recovered are markedly different from rocks of this type that we already know,” said co-author Ivan Savov, a geochemist and volcanologist at the University of Leeds, at one university. Press release. “In fact, they can be as different from known basalts on Earth’s ocean floor as Earth’s basalts are from moon basalts.”

Basalt is a very common type of igneous rock that emerges from cooled lava flows, including currently active volcanoes. But the pressures and temperatures from which the stones emerge completely change their characteristics. The stone, the team reports, probably formed towards the end of the volatile beginnings of the Ring of Fire. It was previously undetected due to its extremely remote (and difficult to access) location.

Although ancient, the Ring of Fire is young in terms of Earth’s tectonic history. Some volcanic rocks date back billions of years, much older than the 49 million years of existence of the new rock.

The team drilled the sample using the JOIDES Resolution, a drilling rig capable of taking samples 6 miles below the surface. (Not quite at a depth of 8 km, the newly reported basalt didn’t even push the limits of the platform.) Under a microscope, a cross section of the stone looks like a freeze frame of a kaleidoscope, a conglomerate of slate grays and sea greens. It comes from the Amami Sankaku Basin, some 600 miles off the coast of Japan. Savov said knowing the conditions that formed this basalt will help Earth scientists better understand the development of the larger formation from which it was drawn.

“At a time when we rightly admire the discoveries made through space exploration, our results show that there are still many discoveries to be made on our own planet,” Savov said in the university statement.

Rocks can tell us a lot about the history of the planet. Most recently, scientists examining rocks in Greenland discovered evidence of a magma ocean that existed when the Earth was just a baby, shortly after the formation of the Moon.