But lava lakes, also exemplified by the Nyiragongo volcano in East Africa, and others, are not found in arc volcanoes like the Cascades and show that there must be something about rift volcanoes that allows magma to reach the surface relatively peacefully. Instead of water, the volatiles in these magmas are CO 2-dominated.Įrebus also has a persistent lava lake, a classic feature of an evolved, CO 2-rich rift volcano. The magmas in the rift zone also have volatiles from the recycling of ocean crust and sediments, but these are much older and are liberated to the surface through the rifting process. Erebus lies along the margin of the West Antarctic Rift System, originating tens of millions of years ago and continuing today. It lies on the eastern boundary of the actively rifting Great Basin geological province and is being slowly stretched east-west. Western Utah is an example of a rift zone. Continental rifting happens as Earth’s crust and mantle are pulled apart. The remaining magma stalls and freezes in place, typically at a depth of around three miles (five kilometers).īut Erebus volcano on Ross Island, Antarctica, is in a continental rift zone. That evolving magma rises into and through the crust but typically does not make it to the surface because, as the pressure from the overlying crust diminishes with ascent, the water flashes out, sometimes explosively as in the case of Mount St Helens in 1980 or Mount Lassen in 1912.
As that ocean crust sinks into the Earth and partially melts, the water in the rocks becomes part of the melt and is the dominant “volatile,” or molecule that easily exsolves or bubbles out of a solution like a fizz out of a carbonated drink. The Cascades are found in a place where Earth’s tectonic plates are pushing toward each other, with the crust of the ocean forced below the crust of the continent. Mount Erebus was first ascended by Shackleton and his party in 1908.Įrebus exemplifies a family of volcanoes with an alkalic chemical composition, with lavas relatively rich in sodium, potassium and other elements including rare earths elements, while being relatively poor in silica.Īlkalic volcanoes are very different from volcanoes such as in the Cascade Range extending from northern California through British Columbia to Alaska. It and its dormant companion volcano, Mount Terror, were named after the exploring ships of Ross, who discovered them and the Transantarctic Mountains in 1841. Mount Erebus is Antarctica’s only active volcano. National Science Foundation, with comparable funding coming from the New Zealand Royal Society Marsden Fund, and in-kind support by participating colleagues. The study was financed by a $464,000 grant from the U.S.
Co-authors also included Erin Wallin of the University of Hawaii and mountaineer Danny Uhlmann, now studying geology at the University of Lausanne. Wannamaker and Hill conducted the study with University of Utah alumni John Stodt and Michal Kordy and associate scientist Virginie Maris geophysicists Paul Bedrosian of the United States Geological Survey, Martyn Unsworth of the University of Alberta, and Yasuo Ogawa of Tokyo Institute of Technology and senior volcanologist Phil Kyle of the New Mexico Institute of Mining and Technology. “Understanding both H 2O and CO 2 volcanoes is important for calculating the budget of such volatile gases deep in the earth that involves an injection of material into Earth’s mantle and its return to the surface to start all over again”, Wannamaker says. “Mount Erebus is an example of a CO 2-dominated rift volcano, a complement to the more widely known arc volcanoes of the Pacific Rim and elsewhere, dominated by H 2O,” adds New Zealand co-investigator Graham Hill, the study’s lead author. The study, published in Nature Communications “expands our understanding of the sources and transport of diverse types of magma and volatile gases to the surface,” says Phil Wannamaker, the study’s second author and a geophysicist at the University of Utah’s Energy & Geoscience Institute. Now, a joint University of Utah and University of Canterbury New Zealand study shows how CO 2 deep underground helps magma avoid being trapped deep in the Earth and allows it to reach and pool at the surface.
A key piece of the puzzle for understanding global continental evolution, Antarctica contains examples that define the spectrum of Earth’s volcanic processes. Antarctica has long been a land of mystery and heroic feats made famous by the explorations of James Ross, Roald Amundsen, Robert Scott and Ernest Shackleton.
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