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The Cretaceous-Paleogene Boundary Essay

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The Cretaceous-Paleogene Mass Extinction

Wil Creasy Student Number: 20921355

The Cretaceous-Paleogene boundary (K-Pg boundary) was host to one of the three largest mass extinctions in the past 500 million years. Evidence suggests it was the result of a large asteroid impact approximately 65.5 million years ago in Chicxulub, Mexico; hence why the crater it formed was named the Chicxulub crater. The crater was approximately 180 kilometres in diameter and was believed to have led to the extinction of the dinosaurs amongst many other life forms including marine plankton (calcareous nannofossils and planktonic foraminifera) (Schulte et al., 2010). Furthermore, it had a number of impacts on the atmosphere and environment including the creation of sulfuric acid rain and stratospheric dust cloud formations. …show more content…

The deposit included a millimeter thick red clay layer that includes an iridium anomaly, ejecta spherules and nickel rich spinel (Schulte et al., 2010). The age of the deposit coincides with the time of the mass extinction. It is coincidences such as this that have led scientists to believe that the mass extinction and the Chicxulub impact are related.

The Yucatan-6 borehole provided significant evidence to suggest that there was an impact event that took place. The composition of the melt rock was believed to have been the result of an impact rather than volcanic events (Kring and Boynton, 1992). What allowed scientists to confirm this, was the surviving clasts of target rock they discovered within the melt, were similar to that seen In the Manicouagan impact crater. (Kring, 2007) Furthermore, these clasts were said to be composed of shocked quarts and feldspar, which are indicative of an impact

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