by Staff Writers
Norregade, Denmark (SPX) Jun 08, 2012
The current theory of continental drift provides a good model for understanding terrestrial processes through history. However, while plate tectonics is able to successfully shed light on processes up to 3 billion years ago, the theory isn't sufficient in explaining the dynamics of the earth and crust formation before that point and through to the earliest formation of planet, some 4.6 billion years ago.
This is the conclusion of Tomas Naaeraa of the Nordic Center for Earth Evolution at the Natural History Museum of Denmark, a part of the University of Copenhagen. His new doctoral dissertation has just been published by the esteemed international scientific journal, Nature.
"Using radiometric dating, one can observe that the Earth's oldest continents were created in geodynamic environments which were markedly different than current environments characterised by plate tectonics.
Therefore, plate tectonics as we know it today is not a good model for understanding the processes at play during the earliest episodes of the Earths's history, those beyond 3 billion years ago.
There was another crust dynamic and crust formation that occurred under other processes," explains Tomas Naeraa, who has been a PhD student at the Natural History Museum of Denmark and the Geological Survey of Denmark and Greenland - GEUS.
Plate tectonics is a theory of continental drift and sea floor spreading. A wide range of phenomena from volcanism, earthquakes and undersea earthquakes (and pursuant tsunamis) to variations in climate and species development on Earth can be explained by the plate tectonics model, globally recognized during the 1960's. Tomas Naeraa can now demonstrate that the half-century old model no longer suffices.
"Plate tectonics theory can be applied to about 3 billion years of the Earth's history. However, the Earth is older, up to 4.567 billion years old. We can now demonstrate that there has been a significant shift in the Earth's dynamics.
Thus, the Earth, under the first third of its history, developed under conditions other than what can be explained using the plate tectonics model," explains Tomas Naeraa. Tomas is currently employed as a project researcher at GEUS.
Central research topic for 30 years
Naeraa's instructor, Professor Minik Rosing of the Natural History Museum of Denmark considers Naeraa's dissertation a seminal work: "We have come to understand the context of the Earth's and continent's origins in an entirely new way. Climate and nutrient cycles which nourish all terrestrial organisms are driven by plate tectonics.
So, if the Earth's crust formation was controlled and initiated by other factors, we need to find out what controlled climate and the environments in which life began and evolved 4 billion years ago.
This fundamental understanding can be of great significance for the understanding of future climate change," says Minik Rosing, who adds that: "An enormous job waits ahead, and Naeraas' dissertation is an epochal step."
Tomas Naeraas' dissertation, "Hafnium isotope evidence for a transition of continental growth 3.2 Gyr ago" was published in Nature May 31.
University of Copenhagen
Explore The Early Earth at TerraDaily.com
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
NASA Astrobiologists Find Iron's Role In Life On Early Earth
Moffett Field CA (SPX) Jun 08, 2012
When life began on Earth, iron may have done the job of magnesium, making life possible. On the periodic table of the elements, iron and magnesium are far apart. But new evidence discovered by the NASA Astrobiology Institute (NAI) team at the Georgia Institute of Technology suggests that three billion years ago, iron did the job magnesium does today in helping Ribonucleic acid (RNA), a molecule ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal 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|