FOX] Scientists have just found the world's longest chain of volcanoes on a continent, hiding in plain sight.
The newly discovered Australian volcano
chain isn't a complete surprise, though: Geologists have long known of
small, separate chains of volcanic activity on the island continent.
However, new research reveals a hidden hotspot once churned beneath
regions with no signs of surface volcanism, connecting these separate
strings of volcanoes into one megachain.
That 1,240-mile-long chain of fire spanned most of eastern Australia,
from Hillsborough in the north, where rainforest meets the Great
Barrier Reef, to the island of Tasmania in the south.
"The track is nearly three times the length of the famous Yellowstone
hotspot track on the North American continent," Rhodri Davies, an earth
scientist at Australian National University, said in a statement. [See Amazing Photos of the World's Wild Volcanoes]
Scientists had long known that four separate tracks of past volcanic
activity fringed the eastern portion of Australia, with each showing
distinctive signs of past volcanic activity, from vast lava fields to
fields awash in a volcanic mineral called leucitite that's dark gray to
black in color. Some of these regions were separated by hundreds of
miles, leading geologists to think the areas weren't connected.
But Davies and his colleagues suspected that the Australian volcanism
had a common source: a mantle plume that melted the crust as the
Australian plate inched northward over millions of years. (Whereas many
volcanoes form at the boundaries of tectonic plates, where hot magma seeps up through fissures in the Earth, others form when mantle plumes, or hot jets of magma, at the boundary between the mantle and Earth's core reach the surface.)
To bolster their hypothesis, Davis and his colleagues used the
fraction of radioactive argon isotopes (versions of argon with different
atomic weights) to estimate when volcanic activity first appeared in
each of these regions. They combined this data with past work showing
how the Australian plate had moved over the millennia. From this
information, they could estimate where and when volcanism affected
certain regions. Read More