Undersea Marianas range resemble Cascades

Imagine the lofty Cascade Range of Oregon at the bottom of the sea, and you can pretty much picture the geography of the Mariana Arc south of Japan.

Oregon State University oceanographic researchers just completed a study of undersea volcanoes in the Mariana Arc, and they said some of the volcanic cones look like an underwater version of Mount Hood, while others resemble Crater Lake.

But instead of forested slopes, fresh alpine air and snow-capped peaks, the undersea volcanic mountain range features plumes of molten sulfur, life forms based on chemical energy instead of sunlight, “black smokers” churning hydrothermal fluids and sometimes explosive underwater eruptions.

The expedition, which recorded a small undersea eruption of an active volcano, was considered a big success, said Bill Chadwick, a volcanologist with the Cooperative Institute for Marine Resource Studies at Oregon State.

The institute, based at the OSU Hatfield Marine Science Center in Newport, works closely with the agency that organized the expedition, the Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration.

“We were just going from one incredible event to the next, seeing things we had never witnessed before,” said Chadwick, a key researcher in the expedition largely funded by NOAA’s Ocean Exploration Program.

“It was very exciting, and quite remarkable in that every volcano we visited seemed to be unique in its own way,” Chadwick said.

The researchers studied how marine life based on photosynthesis in the upper layers of the ocean makes a gradual transition to life further down based on chemosynthesis, or chemical energy.

They found an enormous variation in geology and life forms, which may lead to the identification of new species, including odd microbes, snails, barnacles and worms clinging to hydrothermal vents.

One volcano appeared to have had a catastrophic eruption in its past and had formed a huge caldera just about the same size as the one which holds Crater Lake in southern Oregon.

The geology of the Mariana Arc, which includes such islands as Guam, Saipan and Iwo Jima, is similar to the Cascade Range of the Pacific Northwest. Both are on the so-called “ring of fire” of volcanic mountains around the Pacific rim where huge plates of the Earth’s crust are slowly sliding over each other. (AP)