New Impact Structure Confirmed in Western Australia

A sample of the so-called Mungedar Breccia from the predominantly subsurface Yallalie impact structure, an impact-produced marine rock that contains shocked minerals and rock fragments. Image credit: Martin Schmieder/LPI.

A sample of the so-called Mungedar Breccia from the predominantly subsurface Yallalie impact structure, an impact-produced marine rock that contains shocked minerals and rock fragments. Image credit: Martin Schmieder/LPI

While earlier geologic and geophysical research suggested an impact crater may lie buried some 200 kilometers north of Perth, Western Australia, a new study led by Morgan Cox at Curtin University now provides convincing evidence for meteorite impact in Late Cretaceous time, some 90 to 83 million years ago. Quartz grains in breccia samples from the 12 kilometer-diameter Yallalie impact structure exhibit planar fractures and planar deformation features, telltale signs of shock metamorphism brought about by an impacting asteroid. READ MORE

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