Although Northern Ontario is far from the ocean now, two to three billion years ago, parts of it were actually under the sea. But this marine environment wasn’t always a peaceful place.
Submarine eruptions of lava caused volcanic deposits that were subsequently buried and deformed, folded through extreme pressure, and brought to surface again through erosion.
Ancient examples of these types of rocks, known as volcanogenic massive sulphide (VMS) deposits, are found in the Timmins and Rouyn-Noranda areas of Ontario and Quebec respectively.
To better understand these ancient, mineral-rich deposits, Laurentian University professor Harold Gibson recently travelled half a world away to study similar deposits currently being formed by volcanism under the ocean.
These seafloor massive sulphide (SMS) deposits are actively forming now and some may be about 40,000 years old — positively modern, as far as the rock world goes.
“They provide a very good modern analog to a very ancient ore system,” said Gibson, director of Laurentian’s Mineral Exploration Research Centre (MERC).
Studying how the modern deposits form and why certain minerals end up in certain areas can help exploration companies that explore in Northern Ontario and Quebec, he said.
The more we understand the processes responsible for the formation and location of sea floor massive sulphide deposits, the better we can refine the models that exploration companies use to explore for their ancient, on-land equivalents, said Gibson.
It isn’t currently feasible to mine the modern, underwater deposits themselves, although some companies are looking into it, he said.
The company which has brought seabed mining furthest along is Nautilus Minerals, which is hoping to mine SMS deposits on the ocean floor off Papua New Guinea.
Gibson spent three weeks in December studying SMS deposits on the Southern Central Indian Ocean Ridge off the coast of Madagascar. He was part of an international team of scientists led by Germany’s geological survey, the BGR.
A high-tech, remote-controlled underwater vehicle was used to take high-resolution images of the ocean floor as well as to retrieve samples, which were later examined by scientists.
A type of bucket or dredge was also dragged on the ocean floor behind the ship to collect more samples.
Gibson said he’s studying the geochemistry of these samples to determine the processes responsible for their formation.
Despite 18-hour days, he said he had a great time.
The weather was “marvellous” with temperatures of 28 to 35 degrees Celsius and clear days, Gibson said. “It was a wonderful learning experience.
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