Deformed craton under North America
In the course of billions of years continents break up, drift apart, and are pushed back together again. The cores of continents are, however, geologically extremely stable and have survived up to 3.8 billions of years. These cores that are called cratons are the oldest known geological features of our planet.
It was assumed that the cratons are stable because of their especially solid structure due to relatively low temperatures compared to the surrounding mantle. A team of German-American scientists now discovered that these cratons that were assumed to be “as solid as a rock” are not that solid after all.
The team headed by Dr. Mikhail Kaban from the GFZ German Research Centre for Geosciences now discovered that the craton below the North American continent is extremely deformed: its root is shifted relative to the center of the craton by 850 kilometers towards the west-southwest.
This fact is in contrast to the prevailing assumptions that these continental roots did not undergo substantial changes after their formation 2.5 to 3.8 billion years ago. The study that appears in the latest online publication of "Nature Geoscience" contradicts this traditional view.
“We combined and analyzed several data sets from the Earth’s gravity field, topography, seismology, and crustal structure and constructed a three dimensional density model of the composition of the lithosphere below North America”, explains GFZ scientist Mikhail Kaban. “It became apparent that the lower part of the cratonic root was shifted by about 850 kilometers.”
What caused the deformation of the stable and solid craton? A model of the flows in the Earth’s mantle below North America, developed by the scientists, reveals that the mantle material below 200 kilometers flows westward at a velocity of about 4 millimeters per year.
This is in concordance with the movement of the tectonic plate. Due to the basal drag of this flow the lower part of the cratonic lithosphere is shifted.
“This indicates that the craton is not as solid and as insensitive to the mantle flow as was previously assumed”, Kaban completes. There is far more mechanical, chemical, and thermal interaction between the craton of billions of years in age and its surrounding in the upper mantle of the Earth than previously thought.
Mikhail K. Kaban,Walter D. Mooney and Alexey G. Petrunin, 2015: “Cratonic root beneath North America shifted by basal drag from the convecting mantle”, Nature Geoscience, Advance Online Publication, DOI: 10.1038/NGEO2525
Helmholtz Centre Potsdam
GFZ German Research Centre for Geosciences
- Head, Public Relations -
14473 Potsdam / Germany
Tel. +49 (0)331-288 1040
Fax +49 (0)331-288 1044
Franz Ossing | Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences
NASA sees quick development of Hurricane Dora
27.06.2017 | NASA/Goddard Space Flight Center
Collapse of the European ice sheet caused chaos
27.06.2017 | CAGE - Center for Arctic Gas Hydrate, Climate and Environment
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
27.06.2017 | Power and Electrical Engineering
27.06.2017 | Information Technology
27.06.2017 | Physics and Astronomy