In the Western Australian desert, geologists conducting routine gold surveys uncovered a remarkable discovery: a circular anomaly beneath the eastern goldfield, revealing evidence of a significant ancient catastrophe. This event, believed to be an impact from an iron-rich meteorite, melted rocks and ejected gold-bearing debris into the air. Named the Ola Banda impact structure, it is only the second confirmed impact site formed entirely within Archean greenstone, some of Earth’s oldest rock.
The discovery highlights the role of meteorites in Earth’s history, facilitating the delivery of essential components like water and life-forming molecules to the planet. The crater, despite being geologically younger than the rock it struck, has lost most of its surface expression due to erosion and geological activity, requiring gravity surveys and drill cores for identification.
Key features discovered include shutter cones—indicative of shock waves from the impact—and impact breccia, a rock formed under extreme pressure, which contained metallic elements like nickel and iridium, common in meteorites. Researchers suggest that the impact resulted in an underground structure with concentric rings and may have distributed gold-bearing material into the crater.
Ola Banda offers a unique opportunity to study interactions between meteorite impacts and Earth’s ancient rocks and suggests that other concealed impact structures may lurk beneath greenstone layers worldwide. This research is detailed in “Meteorology and Planetary Science.”
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