[meteorite-list] Chicxulub Crater Has New Impact

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Mar 21 13:24:53 2005
Message-ID: <200503011924.j21JOoL11823_at_zagami.jpl.nasa.gov>

http://www.azcentral.com/news/articles/0301crater01.html

Mexican crater has new impact

UA team taps Earth's past

Chris Hawley
Arizona Republic
March 1, 2005

CHICXULUB PUERTO, Mexico - If time heals all wounds, it has been
especially kind to this town where the Earth nearly died.

Coral reefs, soft sand and a sprinkling of beach houses have covered the
huge crater where something slammed into Chicxulub Puerto eons ago,
turning the world's forests to ashes and, many scientists believe,
killing the dinosaurs and wiping out 99 percent of all life on the planet.

These days, the only things that make landfall here are fishermen and
the occasional bikini-clad tourist.

But among scientists, Chicxulub is becoming one of the most talked-about
places on Earth.

A team of University of Arizona researchers helped find the crater in
the 1990s, and now scientists around the world are trying to piece
together the details of the catastrophe.

Since August, UA geologists David Kring and Lukas Zurcher have published
five papers based on drilling done near the site in 2002. Another team
of scientists is using blasts of sound to map the underwater part of the
crater, a project that has drawn fire from environmentalists and a
possible fine from the Mexican government after the research boat ran
aground.

Other researchers have been studying honeybees for clues and combing
Latin America for debris from the Chicxulub impact.

"We're becoming famous among the scientists," said taxi driver Leonard
Torres Rodriguez. "Now, if only the tourists knew about this place."

The Chicxulub (pronounced CHEEK-SHOO-LOOB) Crater is more than 120 miles
wide. It lies half on land and half underwater on the northern coast of
the Yucat?n Peninsula.

Chicxulub Puerto, a beachside village 12 miles north of the town of
Chicxulub, was ground zero. The area was under water at the time of the
disaster 65 million years ago, and coral reefs and sediment have since
buried the crater a half-mile deep.

Scientists aren't sure whether it was a comet or meteorite that hit the
Earth, but the impact vaporized everything around it, turning Chicxulub
into a lake of molten rock, Kring said.

The blast threw 25 trillion tons of rock into space. The pieces fell
back as a fiery rain of rocks, killing animals and setting most of the
world's vegetation on fire. Dust and smoke blotted out the sun, causing
an artificial winter.

"You could go on for weeks talking about all the environmental effects
this caused," Kring said. "There were magnitude 10 earthquakes, tsunamis
that dwarfed what happened recently in Indonesia, and incinerating heat."

Point of pride

As scientists turn up more information, the long-buried crater has
become a point of pride for residents.

At the Dinosauria exhibit in Merida, just south of Chicxulub, Yucat?n
children gawk at charts comparing the 6-mile-wide meteor or comet to the
world's punier landmarks, like Mount Everest.

"People from these towns never imagined that this place was so
important," guide Alicia Dominguez Rosado said.

In 2002, Kring and other scientists drilled down nearly a mile to pull
up rock samples from the crater. In a series of five papers published
from August to last month, they described how the impact crushed rock,
created a lake of lava the size of the Gulf of California and spawned
hot springs and geysers that pumped away for 2 million years.

"It better tells us how the plumbing worked," Kring said, adding that
similar asteroid impacts may have helped incubate the first life on Earth.

In one study, Kring and others tried, unsuccessfully, to determine
whether the crater was caused by a comet or a meteor. Another study
compared the crater with one in Germany in an attempt to understand how
the impact excavated so much rock.

Meanwhile, two German researchers have been studying debris carried to
northeastern Mexico by the fireball, and an American team has been
mapping the fallout in southern Mexico and Belize. Both reported their
findings this month.

A researcher from the University of New Orleans looked at honeybees,
which survived the "nuclear winter" that followed the blast. Their
survival means the cold spell was not as long as previously thought, the
author said in a paper published in November.

A fourth team of scientists from Mexico, the United States, Australia
and South Africa used radar data from a space shuttle to improve
geologists' view of the crater.

Multinational effort

But the study that has attracted the most attention is a multinational
effort to map the crater by setting off underwater air cannons, then
measuring the echoes through more than 70 sensors on land, 30 on the
seabed and others towed by a ship.

"It's a one-of-a-kind project," said Tim Owen, an engineer from
Cambridge University in England who tends the sensors from a beach house
in Chicxulub. "Normally, we look at underwater ridges and things, not
something extraterrestrial."

Environmental worries

Environmentalists are worried that the noise from the air guns could
harm fish and whales, pointing out that two beaked whales beached
themselves during mapping by the same ship, the RV Maurice Ewing, in 2000.

The scientists claim the air guns cause no harm to marine animals and
say the boat has a team of observers watching with binoculars for any
nearby whales or dolphins.

"I've been on these ships a lot, and you see dolphins playing with the
boat and even among the guns," Owen said. "It's highly unlikely they
would do that if it were uncomfortable for them."

But there was another embarrassment last week, when the boat ran
aground. The Mexican government is trying to determine whether any coral
was damaged and has said the scientists may face a fine.

Meanwhile, people in Chicxulub Puerto said they have seen no fish or
whales killed by the ship's blasts after weeks of mapping.

Some said they were hopeful that the burst of new research would raise
the village's profile and bring in more visitors.

"A museum would be nice," said Torres Rodriguez, the cabdriver.

"I mean, this thing killed almost everything on the Earth. That's
definitely something worth remembering."
Received on Tue 01 Mar 2005 02:24:49 PM PST