Featured Research

from universities, journals, and other organizations

Large landmasses existed 2.7 billion years ago

Date:
January 15, 2014
Source:
University of Cologne - Universität zu Köln
Summary:
Some 71 percent of Earth's surface is covered by oceans and 29 percent by land. The question of when large landmasses emerged from the oceans has always been hotly debated. New investigations by geoscientists have shown that large land masses did indeed exist on Earth 2.7 billion years ago.

Some 71% of Earth's surface is covered by oceans and 29% by land. The question of when large landmasses emerged from the oceans has always been hotly debated by scientists. New investigations by geoscientists of the University of Cologne in cooperation with the University of Bonn and the Jacobs University Bremen have shown that large land masses did indeed exist on Earth 2.7 billion years ago

A Cologne working group involving Prof. Carsten Münker and Dr. Elis Hoffmann and their student Sebastian Viehmann (working with Prof. Michael Bau from the Jacobs University Bremen) have managed for the first time to determine the isotope composition of the rare trace elements Hafnium and Neodymium in 2.7-billion-year-old seawater by using high purity chemical sediments from Temagami Banded Iron Formation (Canada) as an archive.

Earlier work has shown that these rocks from Canada only contain chemical elements that directly precipitated from ocean water. The Temagami Banded Iron Formation, which was formed 2.7 billion years ago during the Neoarchean period, can be used as an archive because the isotopic composition of many chemical elements such as Hafnium and Neodymium directly mirrors the composition of Neoarchean seawater. These two very rare elements allow many valuable conclusions about weathering processes to be drawn.

During their investigations, the research team came to the surprising result that has been published in the journal Geology: 2.7 billion years ago, seawater contained an unusually high abundance of the radioactive isotope Hafnium 176 but a comparably low abundance of the radioactive isotope Neodymium 143, similar to what can be observed in present day seawater.

"In present day seawater, this can be explained by weathering and the erosion of the Earth's exposed surface," explains Prof. Münker. "If in the Neoarchean period 97% of the Earth's surface had been, as estimated from computer models, covered by water, these geochemical signals would not have been found for Neoarchean seawater," adds Dr. Hoffmann.

According to the scientific team, the new findings show that 2.7 billion years ago relatively large landmasses emerged from the oceans that were exposed to weathering and erosion by the sun, wind and rain. Dr. Hoffmann: "The isotope Hafnium 176 in contrast to its counterpart Neodymium 143 was transported by means of weathering into the oceans and became part of iron-rich sediments on the sea floor 2,700 million years ago."

The examinations were carried out in the joint clean laboratory of the Universities of Cologne and Bonn. Prof. Münker: "We are able to carry out these isotope measurements for very rare elements, the concentrations of which are in the ppb range, i.e. only a few parts per billion."


Story Source:

The above story is based on materials provided by University of Cologne - Universität zu Köln. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. Viehmann, J. E. Hoffmann, C. Munker, M. Bau. Decoupled Hf-Nd isotopes in Neoarchean seawater reveal weathering of emerged continents. Geology, 2013; DOI: 10.1130/G35014.1

Cite This Page:

University of Cologne - Universität zu Köln. "Large landmasses existed 2.7 billion years ago." ScienceDaily. ScienceDaily, 15 January 2014. <www.sciencedaily.com/releases/2014/01/140115075414.htm>.
University of Cologne - Universität zu Köln. (2014, January 15). Large landmasses existed 2.7 billion years ago. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/01/140115075414.htm
University of Cologne - Universität zu Köln. "Large landmasses existed 2.7 billion years ago." ScienceDaily. www.sciencedaily.com/releases/2014/01/140115075414.htm (accessed July 31, 2014).

Share This




More Fossils & Ruins News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) — Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
Powered by NewsLook.com
London's Famed 'Gherkin' Goes on Sale for £650 Mln

London's Famed 'Gherkin' Goes on Sale for £650 Mln

AFP (July 29, 2014) — London's "Gherkin" office tower, one of the landmarks on the British capital's skyline, went on sale for about £650 million ($1.1 billion, 820 million euros) on Tuesday after being placed into receivership. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) — The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Tourists Disappointed to Find Rome Attractions Under Restoration

Tourists Disappointed to Find Rome Attractions Under Restoration

AFP (July 26, 2014) — Tourists visiting Italy at the peak of the summer season are disappointed to find some of Rome's most famous attractions being restored and offering limited access. Duration: 01:01 Video provided by AFP
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