In PNAS: Burke and Colleagues
Paper Outlines Deep Mantle Structure as a Reference Frame for Movements In and On the Earth
Kevin C. A. Burke, a professor of geology at the University of Houston, and colleagues in Europe and Africa published the article, “Deep Mantle Structure as a Reference Frame for Movements In and On the Earth,” June 3 in the online Proceedings of the National Academy of Sciences Early Edition. (Article PDF)
For the Earth sciences, the importance of continental drift, the process of change in the relative positions of the continents on the Earth’s surface, has been recognized for the past 100 years. However, quantitative analysis of continental movements for times more than 150 million years ago has not been possible because of the absence of a longer-term reference frame.
In this PNAS article, Burke and co-workers in Europe and Africa have discovered that a stable deep earth structure on the Earth’s core mantle boundary nearly 2,000 miles down inside the Earth provides the needed reference frame.
Using this new discovery for the first time, ancient longitudes and true polar wander (the bodily motion of the solid Earth and its rotation axis) have been quantified for the Earth’s continents for times as long ago as 540 million years, which is the age of the world’s oldest abundant fossil faunas preserved in Cambrian rocks.
This newly published paper (Torsvik et al. PNAS) includes maps of the Earth’s surface for frequent intervals between 250 and 540 million years ago and information that should allow researchers to test for themselves the strength of the new discovery.
A summary of the article appeared in the PNAS’ Highlights from Early Edition for the week of June 2 under the headline, Modeling Movements In and On Earth.