Sulfur-rich ores in Western Australia may have formed from volcanic eruptions

November 28th, 2009 - 4:27 pm ICT by ANI  

Sydney, November 28 (ANI): In a new research, an international team of geologists has determined that sulfur-rich ores that blanket Western Australia may have formed billions of years ago from volcanic eruptions, which eventually settled around hot springs on the ocean floor.

According to a report by ABC News, the research was led by geologists Professor Mark Barley of the University of Western Australia and Assistant Professor Andrey Bekker of the University of Manitoba, Canada.

Western Australia hosts some of the world’s most important nickel-iron deposits, used for steel manufacturing, among other industries.

Many of these nickel-iron ores appear in 2.9 to 1.8-billion year old rocks called komatiites, which formed from very hot magma ejected from deep within the earth.

While sulfur plays an important role in concentrating nickel, the nickel-iron ores formed at a time when the interior of the earth and the ocean was relatively sulfur-poor.

“The question is: where did the sulfur come from?” said Barley.

Bekker and his team analysed the composition of different isotopes of the sulfur and iron within the ore and in adjacent 2.7 billion year old rocks from Australia and Canada.

They found that most of the sulfur in the ore came from volcanic gases that were lifted high into the atmosphere.

This sulfur reacted with ultraviolet (UV) light from the sun, changing the relative concentration of the particles and then deposited on the deep ocean floor.

The UV-altered sulfur in the sediments eventually mixed with molten magma to produce the nickel-iron ore found today.

Barley said that the results are significant for not only understanding early earth systems, but also for pinpointing new nickel-iron deposits.

“It shows that to get really big enrichments of metals you often need very complex interactions of different parts of the earth’s systems,” he said.

According to geologist Professor Ray Cas of Monash University in Melbourne, it is a significant finding because it clarifies the origin of the deposits, which he points out are the world’s major source of nickel.

“It’s giving us a better understanding of the dynamics and relationship between these very exotic old magma types, and clarifies that the sulfur comes from older volcanics with massive sulfide components, which makes a lot of sense,” he said.

Cas said that in terms of exploration potential, the research highlights that komatiites associated with particular volcanic rocks are obviously good places to look for other nickel deposits. (ANI)

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