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How was the buried Chicxulub crater discovered?

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The Chicxulub asteroid — Earth impact hazard An artist's rendering of the impact of a near-Earth object 66 million years ago in what is today the Caribbean region. Many scientists think that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction of dinosaurs and many other species near the end of the Cretaceous Period.

The discovery of the buried Chicxulub crater was a multi-stage process involving geophysical data and geological evidence.1

In the early 1950s, the Mexican oil company Pemex recovered rock samples containing shocked quartz and fused rocks while drilling off the Yucatán Peninsula, though these were initially misidentified as volcanic in origin.1

The breakthrough occurred in 1978 when Pemex geophysicist Glen Penfield analyzed magnetic field and surface gravity data, identifying two large arcs that formed a circle. Although Penfield and his supervisor, Antonio Camargo-Zanoguera, presented these findings in 1981, the discovery gained little initial attention.12

The connection to the K–T extinction was later solidified in 1990 by geologist Alan Hildebrand. After finding tektites in Haiti, Hildebrand contacted Penfield, and together they confirmed that the original Pemex core samples and the Haitian tektites shared the same isotopic composition and age, effectively identifying the site of the asteroid impact that caused the mass extinction.12