Ancient underwater volcanoes led to ice age 750 mln years ago: Aust'n study

The breakup of the ancient supercontinent 750 million years ago led to the formation of an extensive network of underwater volcanos that ultimately plunged the the earth into an ice age, an Australian study has found.

The research team, from the Australian National University (ANU), suggested shallow marine volcanoes - created when ancient supercontinent Rodinia began to split - produced copious amounts of a glassy type of rock known as hyaloclastite.

This substance, which readily breaks down, then released vast amounts of chemicals into the worlds ocean, dramatically altering their makeup.

"In the past, the big question has been: how could large continental weathering deposit so much mineral into the oceans if the land is covered in icesheets," lead author of the study Professor Eelco Rohling told the Australian Broadcast Corporation (ABC) on Tuesday.

"The hyaloclastite eruptions do that - turning the ocean very rich in calcium, magnesium, silicon and phosphorus."

The research, which was published in science journal Nature Geoscience on Tuesday, details the Snowball Earth era, which scientists believe may have left the entire surface of the planet covered in ice.

"A Snowball Earth is an extreme event and the planet almost didn't get out of it," Rohling said.

"Our hypothesis provides a single mechanism that explains several different aspects of the Snowball Earth state."

The extreme glaciation of planet earth, which occurred anywhere between 650 million to 750 million years ago, is widely accepted by scientists.

However, until now a reliable theory into what could have sparked the extreme weather event has been unanswered.

The ANU team, through the aid of simulations, found that the break up of Rodinia was caused by fresh-water runoff entering the ocean and changing the oceans chemical makeup.

In turn, the break created the network of hyaloclastite volcanoes while also reducing the amount of carbon dioxide in the atmosphere, which lead to dramatically lower temperatures.

Once the Snowball Earth was in effect it was able to maintain its state due to the vast ice sheets reflecting the suns rays, the scientists said.

Although volcanoes may have been responsible for propelling the earth into an ice age, eventually their existence lead to earth reestablishing a normal climate.

"Eventually land-based volcanism pumps so much CO2 into the atmosphere that it pushes the planet out of the Snowball Earth phase," Rohling said. Endit