Ancient Asteroid Impact Coated Earth in Blanket of Beads

Theasteroid linked to dinosaurs' demise 65 million years ago slammed into the Yucatan Peninsula with such force it pulverized Earth's crust. The result was a veil ofairborne carbon beads that blanketed the planet, a new study finds.

Spanning about124 miles (200 kilometers), the giant indentation left by the asteroid impactcontinues to be a treasure trove of clues for scientists piecing together the wipe-outof 70 percent of life on Earth, including non-avian dinosaurs. Called the ChicxulubCrater, this CSI-site is located just west of Mexico's Yucatan Peninsula.

Geologistsgenerally agree an asteroid slammed into Earth at the end of the Cretaceousperiod; that the catastrophic impact sent molten rock and super-hot ashairborne; and that as the molten material fell from the sky, it ignitedflammable flora, sparking forest fires.

Moreperplexing has been the formation of carbon particles called cenospheres hidingout in rocks of the Chicxulub Crater and other sites. One idea was that thecarbon beads were charredremnants formed as a result of the plant-burning.

That seemedplausible since, until now, such carbon beads were associated only with modernpower plants, and scientists thought intense burning of coal and crude oilgenerated the structures. Power plants didn't exist 65 million years ago, andeven heat produced by pressure from layers of earth deposited atop the dinofossils would not have been sufficient to form the beads.

However,flames were not needed, say the current researchers, who find besides that thecombustion of plants wouldn't produce such paleo-beads. Rather than a flammableorigin, the carbon beads could have formed from the violent pulverization ofthe Earth's carbon-rich crust.?

Theircounter-view, detailed in this month's issue of the journal Geology,comes from analyses of cenospheres within rock samples collected at oceanic andinland locations around the world.

"Carbon embedded in the rocks was vaporized by the impact, eventuallyforming new carbon structures in the atmosphere," said researcher SimonBrassell, a geologist at Indiana University, Bloomington.

The studywas funded by the Geological Society of America, Indiana University, and theSociety for Organic Petrology.

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