Nav: Home

University of Toronto-led research suggests some major changes to geology textbooks

June 10, 2016

TORONTO, ON - Super-computer modelling of Earth's crust and upper-mantle suggests that ancient geologic events may have left deep 'scars' that can come to life to play a role in earthquakes, mountain formation, and other ongoing processes on our planet.

This changes the widespread view that only interactions at the boundaries between continent-sized tectonic plates could be responsible for such events.

A team of researchers from the University of Toronto and the University of Aberdeen have created models indicating that former plate boundaries may stay hidden deep beneath the Earth's surface. These multi-million-year-old structures, situated at sites away from existing plate boundaries, may trigger changes in the structure and properties at the surface in the interior regions of continents.

"This is a potentially major revision to the fundamental idea of plate tectonics," says lead author Philip Heron, a postdoctoral fellow in Russell Pysklywec's research group in U of T's Department of Earth Sciences. Their paper, "Lasting mantle scars lead to perennial plate tectonics," appears in the June 10, 2016 edition of Nature Communications.

Heron and Pysklywec, together with University of Aberdeen geologist Randell Stephenson have even proposed a 'perennial plate tectonic map' of the Earth to help illustrate how ancient processes may have present-day implications.

"It's based on the familiar global tectonic map that is taught starting in elementary school," says Pysklywec, who is also chair of U of T's Department of Earth Sciences. "What our models redefine and show on the map are dormant, hidden, ancient plate boundaries that could also be enduring or "perennial" sites of past and active plate tectonic activity."

To demonstrate the dominating effects that anomalies below the Earth's crust can have on shallow geological features, the researchers used U of T's SciNet - home to Canada's most powerful computer and one of the most powerful in the world- to make numerical models of the crust and upper-mantle into which they could introduce these scar-like anomalies.

The team essentially created an evolving "virtual Earth" to explore how such geodynamic models develop under different conditions.

"For these sorts of simulations, you need to go to a pretty high-resolution to understand what's going on beneath the surface," says Heron. "We modeled 1,500 kilometres across and 600 kilometres deep, but some parts of these structures could be just two or three kilometres wide. It is important to accurately resolve the smaller-scale stresses and strains."

Using these models, the team found that different parts of the mantle below the Earth's crust may control the folding, breaking, or flowing of the Earth's crust within plates - in the form of mountain-building and seismic activity - when under compression.

In this way, the mantle structures dominate over shallower structures in the crust that had previously been seen as the main cause of such deformation within plates.

"The mantle is like the thermal engine of the planet and the crust is an eggshell above," says Pysklywec. "We're looking at the enigmatic and largely unexplored realm in the Earth where these two regions meet."

"Most of the really big plate tectonic activity happens on the plate boundaries, like when India rammed into Asia to create the Himalayas or how the Atlantic opened to split North America from Europe," says Heron. "But there are lots of things we couldn't explain, like seismic activity and mountain-building away from plate boundaries in continent interiors."

The research team believes their simulations show that these mantle anomalies are generated through ancient plate tectonic processes, such as the closing of ancient oceans, and can remain hidden at sites away from normal plate boundaries until reactivation generates tectonic folding, breaking, or flowing in plate interiors.

"Future exploration of what lies in the mantle beneath the crust may lead to further such discoveries on how our planet works, generating a greater understanding of how the past may affect our geologic future," says Heron.

The research carries on the legacy of J. Tuzo Wilson, also a U of T scientist, and a legendary figure in geosciences who pioneered the idea of plate tectonics in the 1960's.

"Plate tectonics is really the cornerstone of all geoscience," says Pysklywec. "Ultimately, this information could even lead to ways to help better predict how and when earthquakes happen. It's a key building block."
-end-
MEDIA CONTACTS:

Philip Heron
Department of Earth Sciences
University of Toronto
011-0044-7857688947
philip.heron@utoronto.ca

Russell Pysklywec
Department of Earth Sciences
University of Toronto
1- 416-537-2683 (M)
russ@es.utoronto.ca

Sean Bettam
Communications, Faculty of Arts & Science
University of Toronto
1-416-946-7950
s.bettam@utoronto.ca

University of Toronto

Related Plate Tectonics Articles:

The birth and death of a tectonic plate
Geophysicist Zachary Eilon developed a new technique to investigate the underwater volcanoes that produce Earth's tectonic plates
Experts explain origins of topographic relief on Earth, Mars and Titan
The surfaces of Earth, Mars, and Titan, Saturn's largest moon, have all been scoured by rivers.
Scientists describe origins of topographic relief on Titan
Fluid erosion has carved river networks in at least three bodies in our solar system in the form of water on Earth and Mars and liquid hydrocarbons on Titan.
Southern Italy: Earthquake hazard due to active plate boundary
Tectonically, the Mediterranean is extremely active and thus threatened by natural catastrophes.
Release of water shakes Pacific Plate at depth
A team of seismologists analyzing the data from 671 earthquakes that occurred between 30 and 280 miles beneath the Earth's surface in the Pacific Plate as it descended into the Tonga Trench were surprised to find a zone of intense earthquake activity in the downgoing slab.
SLU geologists discover how a tectonic plate sank
Saint Louis University researchers report new information about conditions that can cause the Earth's tectonic plates to sink into the Earth.
The evolution of antibiotic resistance, on a plate
Researchers have developed a large culturing device to track the evolution of bacteria as they mutate in the presence of antibiotics, revealing that, surprisingly, the fittest mutants were not those most likely to infiltrate higher antibiotic concentrations.
Crystallization plate provides clues on protein structure aboard historic space mission
A new crystallization plate, developed and tested at the Cornell High Energy Synchrotron Source, or CHESS, hitched a ride to outer space and is helping a major drugmaker learn about protein structure.
New insights on the relationship between erosion and tectonics in the Himalayas
Can processes unfolding at the Earth's surface be strong enough to influence tectonics?
Earth's mantle appears to have a driving role in plate tectonics
Deep down below us is a tug of war moving at less than the speed of growing fingernails.

Related Plate Tectonics Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Bias And Perception
How does bias distort our thinking, our listening, our beliefs... and even our search results? How can we fight it? This hour, TED speakers explore ideas about the unconscious biases that shape us. Guests include writer and broadcaster Yassmin Abdel-Magied, climatologist J. Marshall Shepherd, journalist Andreas Ekström, and experimental psychologist Tony Salvador.
Now Playing: Science for the People

#514 Arctic Energy (Rebroadcast)
This week we're looking at how alternative energy works in the arctic. We speak to Louie Azzolini and Linda Todd from the Arctic Energy Alliance, a non-profit helping communities reduce their energy usage and transition to more affordable and sustainable forms of energy. And the lessons they're learning along the way can help those of us further south.