Baffin Island lava fields offer clue to Earth’s rocky start

An international team has uncovered evidence of the mother of all Earthly rocks on the east coast of Baffin Island. (PHOTO BY JANE GEORGE)

MARGARET MUNRO
Postmedia News

A relic from Earth’s birth 4.5 billion years ago has surfaced on windswept cliffs in the Canadian Arctic.

“This is the stuff the Earth formed from,” says U.S. planetary scientist Richard Carlson, whose international team has uncovered evidence of the mother of all Earthly rocks on the east coast of Baffin Island.

Carlson, at the Carnegie Institution in Washington, says a “huge blob” of the primordial material bubbled up from inside the Earth to create the immense lava beds that are now home to hungry polar bears.

The findings, reported Thursday in the journal Nature, point to “deep sources” of primordial material inside Earth that have been “effectively isolated for all geological time.” The scientists say they provide insight into both the planet’s beginnings and its inner workings.

Co-author Don Francis, an earth scientist at McGill University, has twice ventured to the lava fields to haul samples of the intriguing rocks back to Montreal. He said Wednesday the wildlife makes the remote area even more forbidding: “There seemed to be a bear every half kilometre.”

Members of his field crew took turns guarding their camp from polar bears at night, and then spent their days collecting the samples that Francis has since shared with earth scientists from around the world.

“Don is a very generous man,” says Carlson, who used sophisticated dating techniques to probe the lava’s origin.

The Baffin rock is not that old — Carlson says it flooded out of a giant crack in the Earth about 60 million years ago. It is the source of the lava that makes it so significant. Chemical isotopes in the lava show it formed from material 4.55 billion to 4.45 billion years old, only slightly younger than the Earth itself.

Carlson describes the primitive material as “the ultimate source of all the magmas and all the different rock types we see on Earth today.”

“It set the stage for everything that came after,” he says.

The scientists say the magma plume that gave rise to the Baffin Island rock also created enormous lava beds in Greenland. They say the plume is still active and responsible for the volcanoes in Iceland that played havoc with air travel earlier this year.