A team of researchers at the Australian National University found the world’s longest continental chain of volcanoes in eastern Australia. The 1,200-mile-long chain stretches from Cape Hillsborough in the north east through Cosgrove in the south east.
Researchers dubbed the newly found volcanic chain Cosgrove hotspot track after a now defunct volcano located in the area. The team estimates that the Australian volcanic chain is three times longer than the famed Yellowstone volcanic chain in North America.
Most of volcanoes in the chain remain active although they aren’t located along tectonic plate edges as most active volcanoes are. Researchers believe that this type of volcanoes stay active because they are located above a 1,800-mile-deep mantle plume laden with molten rock coming from the planet’s depths.
Eastern Australia hosts three other volcanic chains, but the newly discovered chain is by far the longest in the area.
During their research, study authors analyzed 15 inactive volcanoes in the eastern parts of the continent trying to learn whether those volcanoes were part of the same hotspot track. Scientists noticed that these volcanoes shared a set of features. For instance, volcanoes in Victoria, New South Wales and Queensland were ‘younger’ in their southernmost parts.
Next, the research team analyzed the rate of progression of the Australian tectonic plate. This plate is the fastest moving on the planet, with Australia getting closer to Indonesia by 2.7 inches every year.
As a result, scientists found that the 15 volcanoes in Victoria, New South Wales and Queensland drew their energy from the same mantle plume, while the continent was quickly drifting north-northeast.
But past studies failed to realize that those volcanoes were part of the same volcanic chain. Those studies concluded that the volcanoes were two separate chains because the two groups had visible differences in chemical composition and were divided by a 435-mile-wide gap.
Dr Rhodri Davies, lead author of the finding and researcher at the Australian National University, analyzed the thickness of the Earth’s crust underneath the volcanoes. Davies’ team found that the gap between the two groups of volcanoes was caused by a stretch in the crust that was too thick for the mantle plume to melt through it. As a result, there was no apparent volcanic activity or volcanoes at the surface in the region.
Moreover, the thickness of the crust also provided an explanation for the different geochemical composition in the volcanoes. Dr. Davies noted that Queensland volcanoes sat on a 50-mile-thick crust, while those in Victoria and New South Wales drew molten material from 62-mile depths. And, the chemical composition of the molten rock greatly varies depending of the layers of minerals that will enter the melt.
Image Source: Flickr
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