For many, it is a fact that an asteroid impact on Earth was the cause of the massive extinction of species at the end of the Cretaceous, including the dinosaurs, and the role that volcanic activity played in such a catastrophe is still being studied. Recently, a team from the University of Barcelona and the University Institute for Research in Environmental Sciences of Aragon (IUCA-University of Zaragoza) decided to “travel” into the past to investigate the matter.
Their findings, published in the journal geology, ruling out that intense volcanic activity had an influence on species extinction events. According to him, the impact of a giant asteroid caused a biological crisis that wiped out most of life on Earth 66 million years ago.
An area rich in ancient pillars
The researchers focused their study on the slopes of Zumaia, Basque Country, an area rich in ancient pillars and scientific value. In short, it contains a wealth of biological evidence whose analysis can yield a wealth of new information or confirm suspicions.
In the process, they sampled sediment and microfossil-rich rock dating to the period between 66.4 and 65.4 million years ago. To put ourselves in context, this corresponds to a boundary known as the Cretaceous-Paleogene, which coincides with one of the five major species extinctions that occurred on Earth.
Volcanic activity as a possible cause of the end of the extinction
Volcanoes could be a possible cause of biological crises as some studies suggest, albeit from other contexts. This time, they referenced extreme volcanic activity in the Deccan, India, which was one of the most violent volcanic episodes in Earth’s history.
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At Zumaya, two types of sediment have accumulated as a result of this activity: some richer in clay and others richer in carbon now known as strata or marl and limestone. These alternate with each other with a strong rhythm associated with changes in the direction and tilt of the earth’s axis during its rotational and transitional movements.
It should be noted that this difference, known as the Milankovitch cycle, regulates the amount of solar radiation that enters the section; Thus, they also interfere with global temperature regulation.
The sample will allow us to reconstruct the history of climate change that occurred before and immediately after the event and its relationship to it. In this way, they were able to determine whether volcanic activity or changes in Earth’s orbit played a role in the climate crisis at the time, and thus in the mass extinction at the end of the Cretaceous.
Species that went extinct 66 million years ago
The researchers found that more than 90 percent of Cretaceous foraminiferal species in the Zumaya region became extinct 66 million years ago. This was already known, but the discovery yielded new evidence confirming it. The next thing is to confirm the cause.
The extinction coincided with a major disruption of the Earth’s carbon cycle causing climate change. But there was also a massive buildup of glass balls caused by the asteroid impact that hit Chicxulub, on Mexico’s Yucatan Peninsula.
Volcanoes are not the cause of mass extinctions. asteroid impact
The researchers concluded that the maximum eccentricity of the Earth’s orbit around the Sun was due to climate change that occurred in the extension between the late Cretaceous and early Paleogene, between 250,000 years before and 200,000 years after the Cretaceous-Paleogene boundary.
However, it is not related to the mass extinction of late Cretaceous species. “Climate change caused by extreme eccentricity and increased volcanism in the Deccan occurred gradually on a scale of hundreds of thousands of years,” said a statement.
For the researchers, the results are very clear. The cause of the Cretaceous mass extinction was something entirely outside the Earth system: an asteroid impact that occurred 100,000 years after climate change in the Late Cretaceous.
Reference:
Contribution of tropical forcing and Deccan volcanoes to global climate and biotic change across the Cretaceous-Paleogene boundary in Zumaia, Spain. https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G49214.1/607267/Contribution-of-orbital-forcing-and-Deccan
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