Chicxulub Asteroid Still the Cause of Late Cretaceous Mass Extinction Rather than Violent Volcanism, Study Says

A new scientific investigation determined that the early volcanic eruptions on Earth did not have anything to do with mass extinctions back in the late Cretaceous period. Instead, the theory of massive impact that wiped out almost the entire biodiversity of the planet is what appears to be a more plausible cause than spews from the ancient volcanoes. This event 66 million years ago caused a significant decrease in non-avian dinosaurs and marine and terrestrial species, and mere volcanic eruptions did not have any capabilities to inflict such damages compared to the giant space rock that slapped Chicxulub.

The comprehensive study comparing the potential effects between the asteroid impact and the volcanoes in prehistory was conducted through the collaborative efforts of Sietske Batenburg, University of Barcelona's Faculty of Earth Sciences, and the University of Zaragoza's Research Institute on Environmental Sciences.

Cretaceous-Paleogene Mass Extinction

Among the key locations that helped the experts unravel the culprit behind the prehistoric mass extinction is the Zumaia cliffs, located in the Basque Country in the northern regions of Spain. This place was examined and was found to have sedimentary layers of soil piled up to each other called strata. The strata available in the area holds geological information that includes detailed clues from 115 to 50 million years ago. Throughout the analysis, the sediments and rocks embedded with fine 66.4 to 65.4 mega annum microfossils were put under experiment. The experts selected this specific timeline as it is parallel to one of the prehistoric periods of Earth known as the Cretaceous-Paleogene of K/Pg.

The Cretaceous-Paleogene period serves as a boundary between the Mesozoic and Cenozoic eras. Moreover, KP/g is when one of the five most brutal extinctions was incurred by the planet.

Climate change is one of the factors that the experts considered to plot the phases in the atmospheric composition before and after the K/Pg mass extinction occurred. Among the supporting details that showed the difference between climate change during the extinction is the most destructive series of volcanic activities ever occurred in the planet's age right at India's Deccan regions and the orbital shifts of Earth.

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Asteroid vs. Volcano: Sediments, Climate Change, and Earth's Orbit Around the Sun

Sietske Batenburg's Department of Earth and Ocean Dynamics experts said in a report by PhysOrg that the soil composition available at the Zumaia area has types of sediments that are kept over time. The soil samples are rich in carbonate or clay, and the variation and transition between the two types of sediments have been concluded as either marl or strata. In addition, the findings from these rock and soil samples match the supposed inclination of Earth on its orbital axis along with the planet's revolution that cycles around the sun.

The Milankovitch cycles also helped as a guide to determine the regulation of solar radiation emitted towards the planet, affecting its temperature, global climate, and the sediments under the planet's oceanic bodies. The repetition of the Milankovitch cycles was utilized to track every period recorded in the Zumaia sediments, and along with the carbon-13 isotopic examination and hypothermal readings, glass spherules from the Chocxulub asteroid showed up and was determined to have wiped out over 90 percent of the Cretaceous species 66 million years ago. The study was published in the journal Geology, titled "Contribution of orbital forcing and Deccan volcanism to global climatic and biotic changes across the Cretaceous-Paleogene boundary at Zumaia, Spain."