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Geologists Reveal Secrets Behind Supervolcano Eruption

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  • Pat Neuman
    Geologists Reveal Secrets Behind Supervolcano Eruption A piece of supervolcano and extracted quartz crystals analyzed for titanium. by Staff Writers Troy, NY
    Message 1 of 1 , Mar 7, 2007
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      Geologists Reveal Secrets Behind Supervolcano Eruption

      A piece of supervolcano and extracted quartz crystals analyzed for
      titanium.
      by Staff Writers
      Troy, NY (SPX) Mar 07, 2007
      Researchers at Rensselaer Polytechnic Institute have discovered what
      likely triggered the eruption of a "supervolcano" that coated much of
      the western half of the United States with ash fallout 760,000 years
      ago. Using a new technique developed at Rensselaer, the team
      determined that there was a massive injection of hot magma underneath
      the surface of what is now the Long Valley Caldera in California some
      time within 100 years of the gigantic volcano's eruption.
      The findings suggest that this introduction of hot melt led to the
      immense eruption that formed one of the world's largest volcanic
      craters or calderas.

      The research, which is featured in the March 2007 edition of the
      journal Geology, sheds light on what causes these large-scale,
      explosive eruptions, and it could help geologists develop methods to
      predict such eruptions in the future, according to David Wark,
      research professor of earth and environmental sciences at Rensselaer
      and lead author of the paper.

      The 20-mile-long Long Valley Caldera was created when the supervolcano
      erupted. The geologists focused their efforts on Bishop Tuff, an
      expanse of rock that was built up as the hot ash cooled following the
      eruption. The researchers studied the distribution of titanium in
      quartz crystals in samples taken from Bishop Tuff.

      A team from Rensselaer previously discovered that trace levels of
      titanium can be analyzed to determine the temperature at which the
      quartz crystallized. By monitoring titanium, Wark and his colleagues
      confirmed that the outer rims of the quartz had formed at a much
      hotter temperature than the crystal interiors.

      The researchers concluded that after the interiors of the quartz
      crystals had grown, the magma system was "recharged" with an injection
      of fresh, hot melt. This caused the quartz to partly dissolve, before
      starting to crystallize again at a much higher temperature.

      Analyses of titanium also revealed that the high-temperature
      rim-growth must have taken place within only 100 years of the massive
      volcano's eruption. This suggests that the magma recharge so affected
      the physical properties of the magma chamber that it caused the
      supervolcano to erupt and blanket thousands of square miles with
      searing ash.

      "The Long Valley Caldera has been widely studied, but by utilizing
      titanium in quartz crystals as a geothermometer we were able to
      provide new insight into the reasons for its last huge eruption," Wark
      said. "This research will help geologists understand how
      supervolcanoes work and what may cause them to erupt, and this in turn
      may someday help predict future eruptions."

      The research was funded through a grant from the National Science
      Foundation.

      Wark was assisted in his research by Wes Hildreth of the U.S.
      Geological Survey; Frank Spear, Rensselaer professor of earth and
      environmental sciences and department chair; Bruce Watson, Institute
      Professor at Rensselaer, and Daniele Cherniak, research associate
      professor of earth and environmental sciences at Rensselaer.

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      Related Links
      Rensselaer Polytechnic Institute

      http://www.terradaily.com/reports/Geologists_Reveal_Secrets_Behind_Supervolcano_Eruption_999.html
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