The Caribbean islands have been pushed east over the last 50 million years, driven by the movement of the Earth's viscous mantle against the more rooted South American continent, reveals new research by geophysicists from USC.
This is a tectonic map of the southeastern Caribbean with shear-wave splitting measurements
Credit: Courtesy of Meghan Miller and Thorsten Becker
The results, published today in Nature Geoscience, give us a better understanding of how continents resist the constant movement of the Earth's plates – and what effect the continental plates have on reshaping the surface of the Earth.
"Studying the deep earth interior provides insights into how the Earth has evolved into its present form," said Meghan S. Miller, assistant professor of earth sciences in the USC Dornsife College of Letters, Arts and Sciences, and lead author of the paper. "We're interested in plate tectonics, and the southeastern Caribbean is interesting because it's right near a complex plate boundary."
Miller and Thorsten W. Becker, associate professor of earth sciences at USC Dornsife College, studied the margin between the Caribbean plate and the South American plate, ringed by Haiti, the Dominican Republic, Puerto Rico and a crescent of smaller islands including Barbados and St. Lucia.But just like the First Law of Ecology (and time travel), when it comes to the earth, everything really is connected. So to study the motion of the South American continent and Caribbean plate, the researchers had to first model the entire planet – 176 models to be exact, so large that they took several weeks to compute even at the USC High Performance Computing Center.
"If you can, you want to solve the whole system and then zoom in," Becker said. "What's cool about this paper is that we didn't just run one or two models. We ran a lot, and it allowed us to explore different possibilities for how mantle flow might work."
Miller and Becker reconstructed the movement of the Earth's mantle to a depth of almost 3,000 kilometers, upending previous hypotheses of the seismic activity beneath the Caribbean Sea and providing an important new look at the unique tectonic interactions that are causing the Caribbean plate to tear away from South America.
In particular, Miller and Becker point to a part of the South American plate – known as a "cratonic keel" – that is roughly three times thicker than normal lithosphere and much stronger than typical mantle. The keel deflects and channels mantle flow, and provides an important snapshot of the strength of the continents compared to the rest of the Earth's outer layers.
"Oceanic plates are relatively simple, but if we want to understand how the Earth works as a system – and how faults evolved and where the flow is going over millions of years – we also have to understand continental plates," Becker said.
In the southeastern Caribbean, the interaction of the subducted plate beneath the Antilles island arc with the stronger continental keel has created the El Pilar-San Sebastian Fault, and the researchers believe a similar series of interactions may have formed the San Andreas Fault.
"We're studying the Caribbean, but our models are run for the entire globe," Miller said. "We can look at similar features in Japan, Southern California and the Mediterranean, anywhere we have instruments to record earthquakes."
The research was funded by two National Science Foundation CAREER grants.
Meghan S. Miller and Thorsten W. Becker, "Mantle flow deflected by interactions between subducted slabs and cratonic keels," Nature Geoscience. DOI: 10.1038/NGEO1553.
Suzanne Wu | EurekAlert!
Wandering greenhouse gas
16.03.2018 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
Unique Insights into the Antarctic Ice Shelf System
14.03.2018 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
20.03.2018 | Agricultural and Forestry Science
20.03.2018 | Life Sciences
20.03.2018 | Life Sciences