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  (Source: Donald Davis/NASA)
Chicxulub crater may hold clues to one of the world's most catastrophic extinction events

A team of researchers from the University of Texas at Austin's Institute for Geophysics (UTIG), the UK's Imperial College London, the National Autonomous University of Mexico (UNAM), and Centro de Investigación Científica de Yucatán (CICY) are planning an expedition [press release] to sunny southern Mexico in the spring of 2016.  But this will be no ordinary spring break.  The two schools plan to drill into the undersea Chixulub crater, a massive undersea crater located miles off the coast of the Yucatan peninsula.

Many geologists believe that the Chixulub crater -- whose clay stratas are notable for their enrichment with rare elements including iridium -- was the site of an impact of a massive meteor roughly 66 million years ago.  It is estimated that the meteor was at least 10 kilometers (km) (6 miles (mi)) wide and struck with 100 megatons of explosive force -- the equivalent of approximately 2,500 atomic bombs.

The impact is thought to have caused a number of cataclysmic global affects, including kicking up a massive cloud of dust.  It is theorized that the most dominant clade of the time -- Dinosauria (dinosaurs) -- may have mostly died within hours of the impact via a superheating of the atmosphere (although there's evidence that a small number of dinosaurs lived on for some time after the event).  Cumulatively the various catastrophic effects are estimated to have wiped out roughly 75 percent of the Earth's species at the end of the Cretaceous period.

Chicxulub Crater
An artist's depiction shows what the deadly 100 megaton impact may have looked like 66 million years ago. [Image Source: John E. Kaufmann]

The crater was discovered by oil prospecting geophysicists Antonio Camargo and Glen Penfield in 1978.  Evidence that the impact was the causative factor in one of the Earth's most deadly extinction events  -- the so-called "K-Pg Event" (at the Cretaceous-Paleogene) has been growing over the past three decades since the discovery of the impact site.  Once one of a multitude of suspected causes, today researchers believe the evidence points inarguably at the Chicxulub meteor as the culprit.  The new expedition should further strengthen that case.

Crater site
The crater is buried off the coast of southern Mexico. [Image Source: Pearson/Prentice Hall]

The size of the crater is one subect of debate.  Some studies estimate its diameter at 180 kilometers (km) (110 miles (mi)) wide.  A more recent 2006 study [abstract] suggested it actually may be 300 km (190 mi) wide.  Either way the crater is one of the largest confirmed impact craters in the world.

UTIG researcher Sean Gulick and Imperial College of London researcher Joanna Morgan will lead the expedition.  Gulick describes:

What are the peaks made of? And what can they tell us about the fundamental processes of impacts, which is this dominant planetary resurfacing phenomena?

The sediments that filled in the [crater] should have the record for organisms living on the sea floor and in the water that were there for the first recovery after the mass extinction event.  The hope is we can watch life come back.

The drilling expedition will cost roughly $10M USD and will drilled into a feature known as the "peak ring", located 5,000 feet (roughly 1 mile) below the ocean floor near the center of the impact site.

heat map -- Chicxulub
A painting of the impact by NASA illustrator Donald Davis shows pterosaurs gliding frantically as the meteor crashes into the ocean.  Aside it is a gravity map produce from satellite imagery, showing the peak ring. [Image Source: UTIG/NASA]

The sediments of the crater have been explored before, but this will be the first time the central region gets drilled/cored.  Here's the finer details [PDF] of the drilling plans. 

The region is believed by porous and a press release from UTIG suggests that "exotic life that could have thrived in the hot, chemically enriched environment of the crater site."  The team expects to find fossilized signs of such survivors and perhaps even living colonies of ancient extremophiles -- bacteria thriving in hostile environments.  Let's just hope they don't find a Black Marker down there.

Sources: UTIG [press release], via Gizmodo, Imperial College of London [PDF]





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