Geologists find novel basalt type rock deep under the ocean

Apr, 2021 - by CMI


A team of scientists discovered a new form of basalt that is radically different from any other on Earth when digging deep into the seafloor, and the world has not created any more of it in millions of years.

The new rock was found in the Amami Sankaku Basin (ASB), in the ocean south of Japan, by a team of scientists from around the world. The researchers lowered their machinery to the seafloor 6 kilometers (3.7 miles) below the surface, then drilled another 1.5 kilometers (0.9 miles) deep. The team discovered a new form of basalt with a totally different chemical and mineral composition at that depth. It’s a low-titanium, low-potassium tholeiite with aluminum-rich gemstones, which is called spinels.

Dr. Ivan Savov, co-author of the report, states, "The rocks that we recovered are markedly different from rocks of this sort that we already know about." “They may be as isolated from Earth's recognized ocean floor basalts as Earth's basalts are from the Moon's.”

According to geologists, these crystals were formed during massive and extremely hot volcanic eruptions 50 million years ago, when the Ring of Fire was first forming. The magma that produced them was rapidly transported to the surface from its origins in the upper mantle, where it was subjected to pressures ranging from 0.7 to 2 GigaPascals. The chemical and mineral composition of the newly found basalt differs from that of known rocks. These particular rocks have been extinct for millions of years, so these rocks may be considered a Limited Edition.

"Now that we know where and how this rock type is produced, we expect that many other rocks that were formerly thought to have been formed by ocean floor eruptions will be re-examined, possibly changing our interpretation of basalt formation," Savov says.