Crustal boulder tectonics offer clues to Venus geology, study finds
Press release from: Baylor University
Posted: Tuesday June 22 2021
A new analysis of the surface of Venus shows evidence of tectonic movement in the form of crustal blocks that jostled against each other like shattered pieces of ice floe. Posted in the PNAS (Proceedings of the National Academy of Sciences), the study – which includes contributions from Baylor University planetary physicist Peter James, Ph.D. – found that the movement of these blocks could indicate that Venus is still geologically active and give scientists insight into both exoplanet tectonics and the earliest tectonic activity on Earth.
“We have identified a previously unrecognized tectonic deformation pattern on Venus, which is driven by inner movement just as it is on Earth,” said Paul Byrne, Ph.D., associate professor of planetary science at State University from North Carolina and responsible and corresponding co-author of the book. “Although different from the tectonics we are currently seeing on Earth, it is still evidence of an inner movement expressed on the surface of the planet.”
It has long been assumed that Venus has an immobile solid outer shell, or lithosphere, much like Mars or Earth’s moon. In contrast, the Earth’s lithosphere is divided into tectonic plates, which slide against each other, each other, and under each other above a warm, weaker mantle layer.
James, assistant professor of planetary geophysics and founder of the Planetary Research Group at Baylor University, was among the international group of researchers involved in the study. He has participated in three NASA missions and has specialized in using data from spacecraft to study the crusts and mantles of planets and moons.
“Earth is the only planet in the solar system to have plate tectonics, so our planet is quite exceptional in this regard,” said James. “This is particularly interesting when it comes to Venus: why doesn’t a planet like Venus – roughly the same size as Earth and made up of the same types of rocks – behave the same as Earth geologically? “
To answer this question, the team used radar images from NASA’s Magellan mission to map the surface of Venus. Examining the vast Venusian plains that make up most of the planet’s surface, they saw areas where large boulders of the lithosphere appear to have moved: separating, approaching, spinning and sliding over each other. like broken ice on a frozen lake.
James provided calculations of the various mechanisms that could be responsible for the force driving geological activity on Venus. NASA’s Magellan spacecraft measured Venus’s gravity field – the subtle changes in the force of gravity at different places on the planet. James was able to use this gravity field to demonstrate that the viscous mantle flow, or slow churning, is strongly coupled to the crust.
“The mantle inside Venus pushes and pulls on the surface of the planet more strongly than the Earth’s mantle. These motive force calculations corroborated the discovery of the movement of the blocks and helped us better understand how it works,” he said. James said.
The inner mantle flux found by the study’s calculations is significant because it has not been demonstrated globally before. The movement of these crustal blocks could also indicate that Venus is still geologically active.
“We know that a large part of Venus has resurfaced volcanically over time, so parts of the planet could be very young, geologically speaking,” Byrne said. “But several of the jostling boulders formed and deformed these young lava plains, which means that the lithosphere fragmented after the establishment of these plains. This gives us reason to believe that some of these boulders may have moved geologically very recently – perhaps even until today. “
Researchers are optimistic that the newly recognized “ice floe” model of Venus may offer clues to understanding tectonic deformation on planets outside of our solar system, as well as on a much younger Earth.
“One of the benefits of researching planets like this is that it helps us understand why our own planet works the way it does,” James said. “The theme of our planetary research group at Baylor is a quote from Mere Christianism by CS Lewis:“ Aim for Heaven and you will get Earth. ”This quote fits in a spiritual context – we should seek the kingdom of God above all, and then this realm state of mind can even bear fruit in a secular sense. We like the double meaning of using space research to understand our own planet. better. “
Science related to Venus is particularly timely – NASA recently announced that it will send two new spacecraft to Venus, VERITAS and DAVINCI +. These will be the first NASA missions launched to Venus since the 1980s. Additionally, the European Space Agency announced last week that it would send its own spacecraft called Envision to Venus.
“Strategically, this research positions Baylor to be involved in upcoming space missions. Venus is becoming a higher priority for space agencies around the world, and we are connected to the exciting scientific opportunities that lie ahead,” James said.
Baylor will continue to be part of Venus research through James’ lab. Rudger Dame, PhD. candidate in James’ lab, focuses on Venus for his research thesis. He is doing an internship this summer with NASA’s Jet Propulsion Laboratory, under the direction of Sue Smrekar, the principal investigator of the recently announced VERITAS spacecraft.
Additionally, James is collaborating with NASA’s Goddard Space Flight Center to study the crust of the planet Mercury. He also led a recent study published in the journal Geophysical Research Letters on the discovery of a huge and mysterious mass of matter on the far side of the Moon, under the largest crater in our solar system. The mass – at least five times the size of the Big Island of Hawaii – could contain metal from an asteroid that could have crashed into the moon and formed the crater.
The South Pole-Aitken Basin – believed to have been created around 4 billion years ago – is “one of the best natural laboratories for studying catastrophic impact events, an ancient process that shaped all rocky planets and the moons we see today. “
* Sean Solomon of Columbia University is the co-corresponding author. Richard Ghail of the University of London, Surrey; AM Celâl? Engör from Istanbul Technical University; and Christian Klimczak from the University of Georgia also contributed.
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Baylor University is a private Christian university and nationally classified research institution. The University provides a vibrant campus community to over 19,000 students by blending interdisciplinary research with an international reputation for educational excellence and faculty commitment to teaching and scholarship. Established in 1845 by the Republic of Texas through the efforts of Baptist pioneers, Baylor is the oldest operating university in Texas. Located in Waco, Baylor welcomes students from all 50 states and over 90 countries to study a wide range of degrees among its 12 nationally recognized academic divisions.
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