Subscribe free to our newsletters via your
. 24/7 Space News .




DEEP IMPACT
Scientists reconstruct ancient impact that dwarfs dinosaur-extinction blast
by Staff Writers
Washington DC (SPX) Apr 11, 2014


A graphical representation of the size of the asteroid thought to have killed the dinosaurs, and the crater it created, compared to an asteroid thought to have hit the Earth 3.26 billion years ago and the size of the crater it may have generated. A new study reveals the power and scale of the event some 3.26 billion years ago which scientists think created geological features found in a South African region known as the Barberton greenstone belt. Image courtesy American Geophysical Union. For a larger version of this image please go here.

Picture this: A massive asteroid almost as wide as Rhode Island and about three to five times larger than the rock thought to have wiped out the dinosaurs slams into Earth. The collision punches a crater into the planet's crust that's nearly 500 kilometers (about 300 miles) across: greater than the distance from Washington, D.C. to New York City, and up to two and a half times larger in diameter than the hole formed by the dinosaur-killing asteroid.

Seismic waves bigger than any recorded earthquakes shake the planet for about half an hour at any one location - about six times longer than the huge earthquake that struck Japan three years ago. The impact also sets off tsunamis many times deeper than the one that followed the Japanese quake.

Although scientists had previously hypothesized enormous ancient impacts, much greater than the one that may have eliminated the dinosaurs 65 million years ago, now a new study reveals the power and scale of a cataclysmic event some 3.26 billion years ago which is thought to have created geological features found in a South African region known as the Barberton greenstone belt. The research has been accepted for publication in Geochemistry, Geophysics, Geosystems, a journal of the American Geophysical Union.

The huge impactor - between 37 and 58 kilometers (23 to 36 miles) wide - collided with the planet at 20 kilometers per second (12 miles per second). The jolt, bigger than a 10.8 magnitude earthquake, propelled seismic waves hundreds of kilometers through the Earth, breaking rocks and setting off other large earthquakes.

Tsunamis thousands of meters deep - far bigger than recent tsunamis generated by earthquakes - swept across the oceans that covered most of the Earth at that time.

"We knew it was big, but we didn't know how big," Donald Lowe, a geologist at Stanford University and a co-author of the study, said of the asteroid.

Lowe, who discovered telltale rock formations in the Barberton greenstone a decade ago, thought their structure smacked of an asteroid impact. The new research models for the first time how big the asteroid was and the effect it had on the planet, including the possible initiation of a more modern plate tectonic system that is seen in the region, according to Lowe.

The study marks the first time scientists have mapped in this way an impact that occurred more than 3 billion years ago, Lowe added, and is likely one of the first times anyone has modeled any impact that occurred during this period of the Earth's evolution.

The impact would have been catastrophic to the surface environment. The smaller, dino-killing asteroid crash is estimated to have released more than a billion times more energy than the bombs that destroyed Hiroshima and Nagasaki. The more ancient hit now coming to light would have released much more energy, experts said.

The sky would have become red hot, the atmosphere would have been filled with dust and the tops of oceans would have boiled, the researchers said. The impact sent vaporized rock into the atmosphere, which encircled the globe and condensed into liquid droplets before solidifying and falling to the surface, according to the researchers.

The impact may have been one of dozens of huge asteroids that scientists think hit the Earth during the tail end of the Late Heavy Bombardment period, a major period of impacts that occurred early in the Earth's history - around 3 billion to 4 billion years ago.

Many of the sites where these asteroids landed were destroyed by erosion, movement of the Earth's crust and other forces as the Earth evolved, but geologists have found a handful of areas in South Africa, and Western Australia that still harbor evidence of these impacts that occurred between 3.23 billion and 3.47 billion years ago. The study's co-authors think the asteroid hit the Earth thousands of kilometers away from the Barberton Greenstone Belt, although they can't pinpoint the exact location.

"We can't go to the impact sites. In order to better understand how big it was and its effect we need studies like this,' said Lowe. Scientists must use the geological evidence of these impacts to piece together what happened to the Earth during this time, he said.

The study's findings have important implications for understanding the early Earth and how the planet formed. The impact may have disrupted the Earth's crust and the tectonic regime that characterized the early planet, leading to the start of a more modern plate tectonic system, according to the paper's co-authors.

The pummeling the planet endured was 'much larger than any ordinary earthquake," said Norman Sleep, a physicist at Stanford University and co-author of the study. He used physics, models, and knowledge about the formations in the Barberton greenstone belt, other earthquakes and other asteroid impact sites on the Earth and the moon to calculate the strength and duration of the shaking that the asteroid produced. Using this information, Sleep recreated how waves traveled from the impact site to the Barberton greenstone belt and caused the geological formations.

The geological evidence found in the Barberton that the paper investigates indicates that the asteroid was "far larger than anything in the last billion years," said Jay Melosh, a professor at Purdue University in West Lafayette, Indiana, who was not involved in the research.

The Barberton greenstone belt is an area 100 kilometers (62 miles) long and 60 kilometers (37 miles) wide that sits east of Johannesburg near the border with Swaziland. It contains some of the oldest rocks on the planet.

The model provides evidence for the rock formations and crustal fractures that scientists have discovered in the Barberton greenstone belt, said Frank Kyte, a geologist at UCLA who was not involved in the study.

"This is providing significant support for the idea that the impact may have been responsible for this major shift in tectonics," he said.

Reconstructing the asteroid's impact could also help scientists better understand the conditions under which early life on the planet evolved, the paper's authors said. Along with altering the Earth itself, the environmental changes triggered by the impact may have wiped out many microscopic organisms living on the developing planet, allowing other organisms to evolve, they said.

"We are trying to understand the forces that shaped our planet early in its evolution and the environments in which life evolved," Lowe said.

"Physics of crustal fracturing and chert dike formation triggered by asteroid impact, ~3.26 Ga, Barberton greenstone belt, South Africa"; Authors: Norman H. Sleep: Department of Geophysics, Stanford University, Stanford, CA, USA; Donald R. Lowe: Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, USA.

.


Related Links
American Geophysical Union
Asteroid and Comet Impact Danger To Earth - News and Science






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




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





DEEP IMPACT
Asteroid 2007 VK184 Eliminated as Impact Risk to Earth
Pasadena CA (JPL) Apr 04, 2014
Recent observations have removed from NASA's asteroid impact hazard list the near-Earth object (NEO) known to pose the most significant risk of Earth impact over the next 100 years. 2007 VK184, an asteroid estimated to be roughly 130 meters in size, has been on NASA's Impact Risk Page maintained by the NEO Program Office at the Jet Propulsion Laboratory (JPL) for several years, with an est ... read more


DEEP IMPACT
Russian Federal Space Agency is elaborating Moon exploration program

Science, Discovery Channels to broadcast private race to the moon

Take the Plunge: LADEE Impact Challenge

Land a Lunar Laser Reflector Now!

DEEP IMPACT
Mars Exploration in a Deep Mine

Opportunity Moves Further Southwest On Murray Ridge

Images From NASA Mars Rover Include Bright Spots

What's so hard about counting craters?

DEEP IMPACT
Orion Avionics System Ready for First Test Flight

New Catalog Brings NASA Software Down to Earth

Using ethic frameworks for decisions about health standards on long duration spaceflights

China, Asia-Pacific, will power world tourism: survey

DEEP IMPACT
China launches experimental satellite

Tiangong's New Mission

"Space Odyssey": China's aspiration in future space exploration

China to launch first "space shuttle bus" this year

DEEP IMPACT
Progress Departs, New Cargo Ships Awaiting Launch

Progress M-22M to be undocked from ISS and sent on science mission

Russian cargo ship docks to space station

Is "divorce" between Russian and US space agencies possible?

DEEP IMPACT
On-board camera provides a unique perspective on Arianespace Flight VS07

The DZZ-HR satellite is fueled for Arianespace's upcoming Vega launch

EUTELSAT 3B Mission Status Update

Soyuz ready for Sentinel-1A satellite launch

DEEP IMPACT
The Importance of Planetary Plumes

Orbital physics is child's play with 'Super Planet Crash'

Lick's Automated Planet Finder: First robotic telescope for planet hunters

Space Sunflower May Help Snap Pictures of Planets

DEEP IMPACT
Headwall Extends Global Reach in Asia/Pac and Israel

Hyperspectral Software Announced for Airborne Applications

Vanguard Space Technologies Antenna Reflectors on Amazonas Satellite Launch

Materials and electronics that dissolve when triggered




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights 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 Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.