Chicxulub Crater

 

About The Chicxulub Crater

The Chicxulub crater on the Yucatan peninsula is believed to be the most likely site of the asteroid impact responsible for the demise of the dinosaurs.

The crater measures between 180 and 240 kilometres across, indicating an impactor of colossal size, the biggest impact confirmed on Earth. The collision at Chicxulub sent vaporized rocks, cracked mineral grains and molten rock flying around the world. The Chicxulub crater represents the most recent major impact on the Earth, and despite its geologically young age, it is already an extremely well- hidden structure that has taken teams of geologists and geophysicists many years to unravel.

In fact it is so hidden, that nowadays the crater is not noticeable when walking across it, as the crater is merely 3-4 meters deep. At the time of the impact though, the crater probably was over 900 meters deep.

Chicxulub location
Chicxulub Impact - location map

Discovery

The crater was just recently discovered. In 1978, geophysicists Glen Penfield and Antonio Camargo worked for the Mexican state oil company Pemex, as part of an aerial magnetic survey of the Gulf of Mexico, just north of the Yucatan Peninsula. Their job was to use geophysical data to study possible locations to extract oil. During their investigation, they found a big symmetrical underground arc that measured around 70 kilometers.

Pemex map

But this wasn’t the first map Pemex had of that area. Another Pemex contractor, Robert Baltosser made similar discoveries earlier, but was forbid to publish them because of Pemex corporate policy. Consulting the maps made by Baltosser, Penfield found another arc on the peninsula itself. Comparing the two maps, he found that the two arcs formed a circle 180 km in diameter, with its central point near the town of Chicxulub , in the Yucatan. Based on this data, he was sure that the site was a spot of some cataclysmic event in geological history.

Although Pemex forbid them to publish certain data, Penfield and Camargo presented their findings in 1981 at a conference of the Society of Exploration Geophysicists (SEG). At that moment his report attracted little attention because although they had lots of geophysical data, they had no rock samples, or any other physical evidence of the collision.

Concomitantly, American physicist, Luis Walter Alvarez published a paper in which he theorized that the Earth was stuck by a foreign object around the Cretaceous–Paleogene boundary (K-T boundary). After data about the Chicxulub crater was gathered, it was linked to Alvarez’s theory, providing support for it.

Environmental and geological effects of the impact

It is believed that after the impact, some of the biggest tsunamis in Earth’s history were formed. The emission of dust and particles could have covered the entire surface of the Earth for several years, possibly a decade, making life difficult for many terrestrial animals. For some years after the impact, sunlight would have been prevented to reach the surface of the Earth, cooling it down abruptly. Besides the cooling effect, plants wouldn’t have been able to develop, causing devastating effects for the entire food chain.

There are also speculations that the vaporized material might have blown away part of Earth's atmosphere or that the impact would have resulted worldwide forest fires, but these speculations need to be challenged.

Chicxulub crater Yutacan
Chicxulub Crater Yutacan

Chicxulub inner crater at the same scale as the Los Angeles - San Diego area
Chicxulub inner crater at the same scale as the Los Angeles - San Diego area

Chicxulub inner crater at the same scale as the Phoenix and Tucson area
Chicxulub inner crater at the same scale as the Phoenix and Tucson area

Chicxulub inner crater at the same scale as the Washington D.C. - Baltimore area
Chicxulub inner crater at the same scale as the Washington D.C. - Baltimore area

Alternative theories

Although, the theory that the impact at Chicxulub was the one that triggered the extinction of the dinosaurs is widely accepted, some scientists challenged it.

A paper published at the US Proceedings of the National Academy of Sciences argues that the impact predates the K-T boundary by about 300,000 years.

KT boundary

There is also an alternative theory that states that the dinosaurs did not die solely because of the Chicxulub incident, but the impact in Yucatan was just one of many impacts concentrated around the same time, like the 24 km diameter Boltysh crater in Ukraine.

computer generated gravity map of Chicxulub Crater
computer generated gravity map of Chicxulub Crater (c) Source: nasa.gov

Simulating the
Chicxulub Asteroid Impact

Simulating the Chicxulub Asteroid Impact

Simulating the Chicxulub Asteroid Impact

Simulating the Chicxulub Asteroid Impact
(c) Source: lanl.gov