Featured Research

from universities, journals, and other organizations

Geologists Discover New Way Of Estimating Size And Frequency Of Meteorite Impacts

Date:
April 12, 2008
Source:
National Science Foundation
Summary:
Scientists have developed a new way of determining the size and frequency of meteorites that have collided with Earth.

Geologists have discovered a new way of estimating the size of impacts from meteorites.
Credit: NASA

Scientists have developed a new way of determining the size and frequency of meteorites that have collided with Earth.

Their work shows that the size of the meteorite that likely plummeted to Earth at the time of the Cretaceous-Tertiary (K-T) boundary 65 million years ago was four to six kilometers in diameter. The meteorite was the trigger, scientists believe, for the mass extinction of dinosaurs and other life forms.

Franηois Paquay, a geologist at the University of Hawaii at Manoa (UHM), used variations (isotopes) of the rare element osmium in sediments at the ocean bottom to estimate the size of these meteorites. The results are published in this week's issue of the journal Science.

When meteorites collide with Earth, they carry a different osmium isotope ratio than the levels normally seen throughout the oceans.

"The vaporization of meteorites carries a pulse of this rare element into the area where they landed," says Rodey Batiza of the National Science Foundation (NSF)'s Division of Ocean Sciences, which funded the research along with NSF's Division of Earth Sciences. "The osmium mixes throughout the ocean quickly. Records of these impact-induced changes in ocean chemistry are then preserved in deep-sea sediments."

Paquay analyzed samples from two sites, Ocean Drilling Program (ODP) site 1219 (located in the Equatorial Pacific), and ODP site 1090 (located off of the tip of South Africa) and measured osmium isotope levels during the late Eocene period, a time during which large meteorite impacts are known to have occurred.

"The record in marine sediments allowed us to discover how osmium changes in the ocean during and after an impact," says Paquay.

The scientists expect that this new approach to estimating impact size will become an important complement to a more well-known method based on iridium.

Paquay, along with co-author Gregory Ravizza of UHM and collaborators Tarun Dalai from the Indian Institute of Technology and Bernhard Peucker-Ehrenbrink from the Woods Hole Oceanographic Institution, also used this method to make estimates of impact size at the K-T boundary.

Even though these method works well for the K-T impact, it would break down for an event larger than that: the meteorite contribution of osmium to the oceans would overwhelm existing levels of the element, researchers believe, making it impossible to sort out the osmium's origin.

Under the assumption that all the osmium carried by meteorites is dissolved in seawater, the geologists were able to use their method to estimate the size of the K-T meteorite as four to six kilometers in diameter.

The potential for recognizing previously unknown impacts is an important outcome of this research, the scientists say.

"We know there were two big impacts, and can now give an interpretation of how the oceans behaved during these impacts," says Paquay. "Now we can look at other impact events, both large and small."


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Cite This Page:

National Science Foundation. "Geologists Discover New Way Of Estimating Size And Frequency Of Meteorite Impacts." ScienceDaily. ScienceDaily, 12 April 2008. <www.sciencedaily.com/releases/2008/04/080411160239.htm>.
National Science Foundation. (2008, April 12). Geologists Discover New Way Of Estimating Size And Frequency Of Meteorite Impacts. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2008/04/080411160239.htm
National Science Foundation. "Geologists Discover New Way Of Estimating Size And Frequency Of Meteorite Impacts." ScienceDaily. www.sciencedaily.com/releases/2008/04/080411160239.htm (accessed July 23, 2014).

Share This




More Science News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Cargo Craft Undocks from Space Station

Raw: Cargo Craft Undocks from Space Station

AP (July 22, 2014) — A Russian Soyuz cargo-carrying spacecraft undocked from the International Space Station on Monday. The craft is due to undergo about ten days of engineering tests before it burns up in the Earth's atmosphere. (July 22) Video provided by AP
Powered by NewsLook.com
Michigan Plant's Goal: Flower and Die

Michigan Plant's Goal: Flower and Die

AP (July 22, 2014) — An 80-year-old agave plant, which is blooming for the first and only time at a University of Michigan conservatory, will die when it's done (July 22) Video provided by AP
Powered by NewsLook.com
Courts Conflicted Over Healthcare Law

Courts Conflicted Over Healthcare Law

AP (July 22, 2014) — Two federal appeals courts issued conflicting rulings Tuesday on the legality of the federally-run healthcare exchange that operates in 36 states. (July 22) Video provided by AP
Powered by NewsLook.com
Why Do People Believe We Only Use 10 Percent Of Our Brains?

Why Do People Believe We Only Use 10 Percent Of Our Brains?

Newsy (July 22, 2014) — The new sci-fi thriller "Lucy" is making people question whether we really use all our brainpower. But, as scientists have insisted for years, we do. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins