Featured Research

from universities, journals, and other organizations

New Method Of Dating Oceanic Crust Is Most Accurate So Far

Date:
November 1, 2005
Source:
National Science Foundation
Summary:
A newly developed method that detects tiny bits of zircon in rock reliably predicts the age of ocean crust more than 99 percent of the time, making the technique the most accurate so far. After collecting zircon-bearing samples of ocean crust, the scientists used a Sensitive High Resolution Ion Micro Probe (SHRIMP) to determine the absolute ages of 17 samples from Atlantis Bank about 75 miles south of the Southwest Indian Ridge in the southern Indian Ocean.

Tiny crystals called zircons, used to date oceanic crust, are relatively common in rocks known as gabbros.
Credit: Michael John Cheadle, University of Wyoming

A newly developed method that detects tiny bits of zircon in rock reliably predicts the age of ocean crust more than 99 percent of the time, making the technique the most accurate so far.

After collecting zircon-bearing samples of ocean crust, the scientists used a Sensitive High Resolution Ion Micro Probe (SHRIMP) to determine the absolute ages of 17 samples from Atlantis Bank about 75 miles south of the Southwest Indian Ridge in the southern Indian Ocean. About 25 percent of the samples were 2.5 million years older than predicted by conventional models of crust generation at mid-ocean ridges.

"This research advances our understanding of how oceanic crust is formed, and the processes involved in that formation," says Mike Cheadle, geologist at the University of Wyoming (UW) and coauthor of an article describing the technique in the Oct. 28 issue of the journal Science.

Zircons are widely regarded as providing the best basis for finding the absolute age of rocks on land, according to Cheadle's coworker, Barbara John, who is also geologist at UW. The zircon dating technique has been used extensively to answer questions such as when and how fast the Earth's continental crust forms. But until now, scientists have relied on geophysical methods based on magnetism to date ocean crust.

As the Earth's tectonic plates separate over time, new crust is created at mid-ocean ridges, says John. Minerals in the rocks that make up the crust are magnetized in the direction of the Earth's magnetic field as they cool and freeze. Because the field reverses polarity over time, the rocks record the polarity, creating alternating stripes on either side of a mid-ocean ridge.

Traditionally, instruments aboard ships have predicted the age of the ocean's crust by mapping these magnetic stripes, and then calculating an age using distance and time between polarity reversals within the crust, says Rodey Batiza, program director in the National Science Foundation (NSF)'s Division of Ocean Sciences, which funded the research. But that method does not reveal the entire process involved in the growth of ocean crust, he says.

Joshua Schwartz, the paper's first author and a UW Ph.D. candidate in geology, says the team's research offers another tool to understand the complex processes occurring beneath the Earth's surface. "Our finding that these zircons are older than they should be relative to their magnetic age alters what we've thought about oceanic crust, he says. "The ability to date zircons in ocean crust offers another and better way to determine how ocean crust is formed."

Adds Cheadle, "Findings about today's ocean ridges help us to better understand how the Earth has worked in the past."

Other co-authors of the paper are affiliated with the U.S. Geological Survey in Menlo Park, Calif., and the Woods Hole Oceanographic Institution in Woods Hole, Mass.


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. "New Method Of Dating Oceanic Crust Is Most Accurate So Far." ScienceDaily. ScienceDaily, 1 November 2005. <www.sciencedaily.com/releases/2005/10/051031133533.htm>.
National Science Foundation. (2005, November 1). New Method Of Dating Oceanic Crust Is Most Accurate So Far. ScienceDaily. Retrieved April 24, 2014 from www.sciencedaily.com/releases/2005/10/051031133533.htm
National Science Foundation. "New Method Of Dating Oceanic Crust Is Most Accurate So Far." ScienceDaily. www.sciencedaily.com/releases/2005/10/051031133533.htm (accessed April 24, 2014).

Share This



More Earth & Climate News

Thursday, April 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

UN Joint Mission Starts Removing Landmines in Cyprus

UN Joint Mission Starts Removing Landmines in Cyprus

AFP (Apr. 23, 2014) — The UN mission in Cyprus (UNFICYP) led a mine clearance demonstration on Wednesday in the UN-controlled buffer zone where demining operations are being conducted near the Cypriot village of Mammari. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
California Drought Is Good News for Gold Prospectors

California Drought Is Good News for Gold Prospectors

AFP (Apr. 22, 2014) — For months California has suffered from a historic drought. The lack of water is worrying for farmers and ranchers, but for gold diggers it’s a stroke of good fortune. With water levels low, normally inaccessible areas are exposed. Duration: 01:57 Video provided by AFP
Powered by NewsLook.com
Raw: MN Lakes Still Frozen Before Fishing Opener

Raw: MN Lakes Still Frozen Before Fishing Opener

AP (Apr. 22, 2014) — With only three weeks until Minnesota's fishing opener, many are wondering if the ice will be gone. Some of the Northland lakes are still covered by up to three feet of ice, causing concern that just like last year, the lakes won't be ready. (April 22) Video provided by AP
Powered by NewsLook.com
Scientists Warn Of Likely El Niρo Event This Year

Scientists Warn Of Likely El Niρo Event This Year

Newsy (Apr. 22, 2014) — With Pacific ocean water already showing signs of warming, the NOAA says there's about a 66 percent chance the event will begin before November. 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