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    Meteorite turned earth inside out


    Toronto (SPX) Jun 04, 2004

    A devastating meteorite collision caused part of the Earth's crust to flip inside out billions of years ago and left a dusting of a rare metal scattered on the top of the crater, says new University of Toronto research.

    The study, published in the June 3 issue of Nature, examines the devastating effects of meteorite impacts on the Earth's evolution. Researchers from the University of Toronto and the Geological Survey of Canada studied the remains of a 250-kilometre wide crater in Sudbury, Ontario, known as the Sudbury Igneous Complex, caused by a collision with a Mount Everest-sized meteorite 1.8 billion years ago.

    They discovered that the meteorite burrowed deep into the Earth's upper crust - which measures an average of 35 kilometres thick - and caused the upper crust to be buried under several kilometres of melted rock derived from the lower crust.

    The dynamics of meteorite impacts remain a source of debate among researchers and, until now, there has been little hard evidence to prove a meteorite could pierce through the Earth's upper crust and alter its compositional makeup.

    "It had not really been appreciated that large impacts would selectively move material from the bottom of the crust up to the top," says lead researcher James Mungall, a U of T geology professor. "This has been suggested for the Moon at times in the past but ours is the first observational evidence that this process has operated on Earth."

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