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What evidence links the Chicxulub crater to the Cretaceous-Paleogene extinction?
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Cretaceous Period
Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cretaceous Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.
The link between the Chicxulub crater and the Cretaceous-Paleogene (K-T) extinction is supported by significant geological evidence found in rock layers dating to the end of the Cretaceous Period.12
Key evidence includes:
- Iridium Anomalies: A global layer of clay found between Cretaceous and Paleogene rock strata contains high concentrations of iridium. Because this element is rare in Earth's crust but abundant in meteorites, it serves as a signature of an extraterrestrial impact.12
- Impact Debris: Deposits associated with the extinction event contain tektites—natural glass formed by the intense heat and pressure of an impact—and shocked quartz.12
- Crater Characteristics: Geophysical data, including magnetic and gravity anomalies, identified the 180-km-wide crater buried beneath the Yucatán Peninsula. Core samples from this site confirm the presence of fused rocks and isotopic compositions consistent with the timing of the extinction.13
- Environmental Indicators: Evidence of a massive tsunami and widespread wildfires, along with global dust layers, corroborates the theory that the impact triggered catastrophic climate change, blocking sunlight and disrupting the food chain.12