International research led by geologists from Â鶹ֱ²¥ has found that a volcanic province in the Indian Ocean was the world\u2019s most continuously active \u2014 erupting for 30 million years \u2014 fuelled by a constantly moving \u2018conveyor belt\u2019 of magma.<\/p>\n
It\u2019s believed this magma \u2018conveyor belt,\u2019 created by shifts in the seabed, continuously made space available for the molten rock to flow for millions of years, beginning around 120 million years ago.<\/p>\n
Research lead Qiang Jiang, a PhD candidate from Curtin\u2019s School of Earth and Planetary Sciences, said the studied volcanoes were in the Kerguelen Plateau, located in the Indian Ocean, about 3,000 kilometres south west of Fremantle, Western Australia.<\/p>\n
\u201cExtremely large accumulations of volcanic rocks \u2014 known as large volcanic provinces \u2014 are very interesting to scientists due to their links with mass extinctions, rapid climatic disturbances, and ore deposit formation,\u201d Mr Jiang said.<\/p>\n
\u201cThe Kerguelen Plateau is gigantic, almost the size of Western Australia. Now imagine this area of land covered by lava, several kilometres thick, erupting at a rate of about 0.2 millimetres every year.<\/p>\n
\u201c0.2 millimetres of lava a year may not sound like much but, over an area the size of Western Australia, that\u2019s equivalent to filling up 184,000 Olympic-size swimming pools to the brim with lava every single year. Over the total eruptive duration, that\u2019s equivalent to 5.5 trillion lava-filled swimming pools!<\/p>\n
\u201cThis volume of activity continued for 30 million years, making the Kerguelen Plateau home to the longest continuously erupting supervolcanoes on Earth.\u00a0 The eruption rates then dropped drastically some 90 million years ago, for reasons that are not yet fully understood.<\/p>\n
\u201cFrom then on, there was a slow but steady outpouring of lava that continued right to this day, including the 2016 eruptions associated with the Big Ben volcano on Heard Island, Australia\u2019s only active volcano.\u201d<\/p>\n
Co-researcher Dr Hugo Olierook, also from Curtin\u2019s School of Earth and Planetary Sciences, explained such a long eruption duration requires very peculiar geological conditions.<\/p>\n
\u201cAfter the partial breakup of the supercontinent Gondwana, into the pieces now known as Australia, India and Antarctica, the Kerguelen Plateau began forming on top of a mushroom-shaped mantle upwelling, called a mantle plume, as well as along deep sea, mid-oceanic mantle ridges,\u201d Dr Olierook said.<\/p>\n
\u201cThe volcanism lasted for so long because magmas caused by the mantle plume were continuously flowing out through the mid-oceanic ridges, which successively acted as a channel, or a \u2018magma conveyor belt\u2019 for more than 30 million years.<\/p>\n
\u201cOther volcanoes would stop erupting because, when temperatures cooled, the channels became clogged by \u2018frozen\u2019 magmas.<\/p>\n
\u201cFor the Kerguelen Plateau, the mantle plume acts as a Bunsen burner that kept allowing the mantle to melt, resulting in an extraordinarily long period of eruption activity.\u201d<\/p>\n
Research co-author, Professor Fred Jourdan, Director of the Western Australia Argon Isotope Facility at Â鶹ֱ²¥, said the team used an argon-argon dating technique to date the lava flows, by analysing a range of black basaltic rocks taken from the bottom of the sea floor.<\/p>\n
\u201cFinding this long, continuous eruption activity is important because it helps us to understand what factors can control the start and end of volcanic activity,\u201d Professor Jourdan said.<\/p>\n
\u201cThis has implications for how we understand magmatism on Earth, and on other planets as well.\u201d<\/p>\n
The Curtin-led research was a collaboration with Uppsala University in Sweden and the University of Tasmania.<\/p>\n