Baffin Island lava offers clue to Earth’s early life

Lava samples from Arctic Canada have helped an international team of scientists unlock another clue to the origins of the Earth’s first water billions of years ago thanks to an intrepid Canadian geologist and his love of the North.

It has been 11 years since Don Francis, a recently retired professor at McGill University’s department of earth and planetary sciences, visited some of the most remote reaches of Baffin Island to gather the samples. It was not an easy task.

“It’s a bit of an expedition,” says Francis, who, along with two colleagues, flew to Iqaluit and then to the remote Inuit village of Qikiqtarjuaq, on the east coast of the island.

From there, they hired an Inuit boat to take them about 90 kilometres south along the coast.

They travelled light and slept in tents over the two-week voyage, gathering samples at several locations.

“Global warming has had a big effect up there. There’s no more sea ice so all the polar bears, rather than being out on the ice, are on the shore,” Francis says. “So, as we were motoring down the shore there would be a group of polar bears every half kilometre and that was a little intimidating.”

They had a bear dog with them but had to keep guard 24 hours a day for any sign of the land-bound bruins.

The team was looking for a type of lava called picrite, but not just any picrite. The isotopes in picrite from Baffin Island suggest the lava there melted from a very ancient source from the early life of Earth.

“That area is quite spectacular because there are cliffs that rise out of the sea for up to 3,000 feet, so the challenge is actually to get to them on the cliff,” Francis says.

The cliffs are too unstable to climb so the trio had to find gullies to hike up. Way up.

“I have a rule of thumb that if my dog is afraid to go then that’s when I should stop,” says Francis.

Samples gathered, he set to work studying these high-magnesium lavas for evidence of changes in the earth’s mantle over billions of years.

He wasn’t the only scientist interested in the unique lava samples. Requests began to come in for the hard-won specimens taken from the Baffin Island cliffs with sledgehammers.

Over the years, Francis has provided dozens of samples to four or five different researchers.

One of them was Lydia Hallis, an isotopic geochemist now at the University of Glasgow, then with the NASA Astrobiology Institute at the University of Hawaii.

“We were aiming to measure samples that had high [hydrogen] isotope ratios, as this shows that a sample originates from a mantle source region that is primordial,” Hallis says in an email exchange.

Such pristine samples as those found on Baffin Island are rare.

“Only certain areas on Earth erupt lavas with high He isotope ratios, and Baffin Island is the place with the highest ratios (indicating its source is the most primordial, meaning it represents the composition of the early Earth).”

Tests indicated the source of the lava had been untouched for 4.5 billion years, with no contamination from Earth’s crustal rocks, she says.

Analysis of the deuterium/hydrogen isotope ratio in the Baffin Island specimens suggests that water-soaked dust grains, present as the planets were just beginning to form in our solar system, embedded within the Earth during its formation. Their research is published in this week’s issue of Science.

“Our research indicates that water is an integral part of planet formation, and that water is retained in the planet during the formation process. This indicates that rocky bodies should be water rich,” Hallis says.

“Indeed this finding is backed up by recent images and measurements of Mars, asteroids and the moon, all of which have been found to contain much more water than we would have expected even 10 years ago.”

Samples from Francis’s 2004 expedition were also sent to the University of Quebec and the Carnegie Institution for Science, both of which are expected to publish results of their own studies in the near future.

“They’ve turned out to be quite interesting,” says Francis, whose work has taken him from the Yukon to northern Quebec, where he found what are believed to be the oldest rocks ever found on Earth — 4.3 billion years old.

“I like the expedition part of it,” he says.