. 24/7 Space News .
Chicxulub Didnt Kill The Dinosaurs

Scanning Electron Microscope picture of isolated, and well preserved Spherule from NE-Mexico (400 �m in diameter).
by Staff Writers
Boulder CO (SPX) Mar 30, 2006
A new study of melted rock ejected far from the Yucatan's Chicxulub impact crater bolsters the idea that the famed impact was too early to have caused the mass extinction that killed the dinosaurs 65 million years ago.

A careful geochemical fingerprinting of glass spherules found in multiple layers of sediments from northeast Mexico, Texas, Guatemala, Belize, and Haiti all point back to Chicxulub as their source. But the analysis places the impact at about 300,000 years before the infamous extinctions marking the boundary between the Cretaceous and Tertiary periods, a.k.a. the K-T boundary.

Using an array of electron microscopy techniques, Markus Harting of the University of Utrecht in the Netherlands has found that chemical compositions of the spherules all match what would be expected of rocks melted at the Chicxulub impact. The spherules are now found in several layers because after they originally hit the ground, they were "reworked" by erosion to create later layers of sediments, he said. It's this reworking long after the impact that has misplaced some of the spherules into sediments that, based on the fossils in the same sediments, are misleadingly close to the K-T boundary.

Harting is scheduled to present his latest findings on Monday, 3 April Backbone of the Americas-� Patagonia to Alaska. The meeting is co-convened by the Geological Society of America and the Asociacion Geologica Argentina, with collaboration of the Sociedad Geologica de Chile. The meeting takes place 3-7 April in Mendoza, Argentina.

"The whole story is that it's a single impact event," said Harting of his analysis of the multiple spherule layers. In fact, the original spherule layer is not particularly hard to make out, since its spherules are not as abraded and damaged as those which were moved around and re-deposited in later, higher sediments. Above these, and younger still, Harting has also identified the famous layer of extraterrestrial iridium in sediments worldwide which was originally touted as the smoking gun for an impact somewhere on Earth at the K-T boundary.

"In most of the sections we found spherules we also found the iridium layer at or near the K-T boundary," said Harting. "That makes the mismatch with Chicxulub even more obvious."

The sediments from the region are also providing clues to what transpired during those 300,000 years between the impact and the K-T boundary die-offs. "Nothing happened between them," said Harting. "The K-T iridium layer is a totally different event."

Disconnecting the Chicxulub impact from the K-T boundary also helps make sense of some other oddities in the iridium layer. In the Gulf of Mexico, close to the impact site, iridium is found at a weak concentration, just one part per billion, says Harting. Yet farther away in Denmark, higher concentrations of iridium are found. "This doesn't really make sense," he said, unless, of course, the impact and iridium layer are not related.

All this begs the question: What, then, created the worldwide iridium layer, if not a humongous impact? One possibility is that Earth and perhaps the entire solar system were passing through a thick cloud of cosmic dust 65 million years ago.

"You probably have a time when lots of meteorites are coming down and never touching the ground," said Harting. Instead they burned up as "shooting stars," depositing their iridium in the atmosphere. There it was quickly rained out, washed into lakes and oceans and buried in contemporary sediments.

Another burning question is whether the massive impact - which undoubtedly occurred and was certainly catastrophic - is responsible for any extinction at all. Maybe, answers Harting. There is the case of the ammonites, the once ubiquitous nautilus-like sea creatures that died out at about the same time as the Chicxulub impact and before the K-T boundary, he said.

But whether the impact was the ammonite killer is not at all clear, according to Harting. Early models of the Chicxulub impact called on a "nuclear winter" scenario, in which a dust-shrouded world went cold and plant life died away for years, to cause mass extinctions. Yet sun-loving animals like crocodiles and turtles appear to have glided right through without any ill effects. And that is, perhaps the silver lining to Chicxulub's fall from the status of most-massive-of-all-murderers: Even giant impacts aren't necessarily global catastrophes.

When and Where
Backbone of the Americas � Patagonia to Alaska Centro de Congresos Mendoza, Argentina Monday, 3 April

Related Links
Backbone of the Americas � Patagonia to Alaska
Geological Society of America
Asociacion Geologica Argentina
Sociedad Geologica de Chile



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


Mile Wide Asteroid Passes Close On Monday
Boulder CO (SPX) March 5, 2006
An asteroid named 2000 PN9 will fly past Earth at a distance of about 2 million miles on March 6. There is no danger of a collision with the mile-wide space rock, but its nearest approach distance of eight lunar distances - on average, the Moon is 384,401 kilometers, or 246,017 miles away.







  • Space Adventures Chooses Singaporean Venue And Russian Vehicle Producer
  • Orthodox Blessings And Champagne For Brazil's First Astronaut
  • NASA Extends CEV Contracts
  • Headdown Bedrest Precisely Mimics Human Physiology In Spaceflight

  • Mars Rover Team Investigating Spirit's Front Wheel
  • IXSEA Announces 3 Million Euro Space Deal
  • Mars Express Images Huge Ancient Valley
  • MRO Returns First HiRISE Images of Mars

  • Next Ariane 5 Launch Taking Shape
  • ATK Rocket Motors Power Successful Launch of Pegasus XL
  • NASA Is 'Three For Three' In Successful ST5 Launch
  • Washington Touts US-Russian Satellite Launch Cooperation

  • Envisat Makes Direct Measurements Of Ocean Surface Velocities
  • NASA Scientist Claims Warmer Ocean Waters Reducing Ice Worldwide
  • Space Tool Aids Fight For Clean Drinking Water
  • FluWrap: Deadly Strain Divides

  • "Zero G and I Feel Fine"
  • To Pluto And Beyond
  • New Horizons Update: 'Boulder' and 'Baltimore'
  • New Horizons Set For A Comfortable Cruise Out To Jupiter And Pluto Transfer

  • The Eye Of God Returns
  • Chandra Finds Evidence For Quasar Ignition
  • Chandra Finds Evidence Of How Quasars Ignite
  • Carnegie Scientists Fine-Tuning Methods For Stardust Analysis

  • SMART-1 Tracks Crater Lichtenberg And Young Lunar Basalts
  • Quantum Technique Can Foil Hackers
  • Noah's Ark On The Moon
  • X PRIZE Foundation And The $2M Lunar Lander Challenge

  • New York School Districts Install GPS Tracking Systems in Buses
  • Glonass System To Open For Russian Consumers In 2007
  • TomTom Unveils a Range of New and Updated Content And Services
  • RFID-Based Asset Management With Innovative Sensory Technology

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement