The new basalt has just fallen. An international team of scientists drilled nearly a mile into the bottom of the Pacific Sea and extracted a variety of volcanic rock chemically and mineralogically different from any previously known.
The team examined a 49-million-year-old rock outcrop that formed just a few million years after the Ring of Fire, that famous half-month of volcanic activity bordering the Pacific. In the first few million years after its ignition, the ring broke with an overheated intensity, according to the team, formed a unique type of stone.
They brought this evidence of Earth’s history from almost 5 miles below the surface of the ocean. 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 have recovered are distinctly different from the rocks of this type that we already know,” said co-author Ivan Savov, a geochemist and volcanologist at the University of Leeds at a university. Press release. “In fact, they may be as different from the known ocean floor basalts on Earth as they are from Earth’s basalts to the moon’s basalts.”
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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 come out completely change their characteristics. The stone, the team reports, was 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 the tectonic history of the Earth. Some volcanic rocks date back billions of years, much older than the new rock’s 49 million years of existence.
The team drilled the test using JOIDES resolution, a drilling rig capable of extracting samples from 6 miles below the surface. (Not even at a depth of 5 miles, the newly reported basalt did not even exceed the limits of the platform.) Under the microscope, a cross section of the stone looks like a frozen frame in a kaleidoscope, a conglomerate of slate gray. and sea green. It comes from the Amami Sankaku Basin, about 600 miles off the coast of Japan. Savov said that knowing the conditions that formed this basalt will help scientists on Earth to better understand the development of the larger formation from which it was extracted.
“In an era in which we rightly admire the discoveries made by exploring space, our discoveries show that there are still many discoveries to be made on our own planet,” Savov said in a university statement.
The rocks can tell us a lot about the history of the planet. Recently, scientists examining the rocks of Greenland have discovered evidence of a magmatic ocean which existed when the Earth was just a child, not long after the Moon was formed.