New evidence of geologically recent Venusian volcanism

Magellan SAR image of Aramaiti Corona. Narina Tholus (center left) appears as two adjacent domes superimposed on the outer west fracture ring. Credit: Institute of Planetary Sciences

New data analysis techniques are finding evidence of recent volcanism in old data from Magellanic spacecraft. It is not known if this activity occurs today, or if it occurred tens of millions of years ago, but geologically speaking, both cases are recent. This adds to the growing body of evidence that the volcanoes of Venus did not go extinct as long as many thought. This work was conducted by Planetary Science Institute (PSI) researchers Megan Russell and Catherine Johnson.

In the 31 years since NASA’s Magellan spacecraft orbiting Venus, researchers have used the mission’s radar imagery, topography, and gravity mapping to understand the history of the surface. of this cloud-covered world. The first results clearly showed that Venus has far fewer impact craters on its surface than its cousins ​​Mars and Mercury, and that the craters it does have are scattered randomly across the planet. Craters build up over time, and Venus’ low number of craters means it has an area that was sort of cleaned up around 300 million to 1 billion years ago. It is not known whether this was a catastrophic event that resurfaced both across the entire planet, or on-going randomly distributed events that systematically resurfaced on Venus over time, or a combination of the two options. To understand what happened, it is necessary to understand when the volcanoes were active.

“Whether Venus had geologically recent or ongoing volcanism has been a lingering conundrum of the Magellan mission: we still don’t have a smoking weapon on it, but more and more evidence suggests a planet active recently and potentially currently, “said Catherine Johnson, PSI Principal Scientist.

As computers improved, it became possible to do more and more with the finished Magellan dataset. Russell and Johnson used a high-resolution stereo topography dataset generated by other researchers to examine a volcano bordering 350 kilometers through Aramaiti Corona.

Crowns are roughly circular features surrounded by a ring of cracks that roughly resemble a crown, and are considered large faults. At the level of certain crowns, such as Aramaiti, volcanoes and / or lava flows are observed near or on these fractures. The volcano studied by PSI researchers was among the lucky 20% of the surface of Venus to be imaged in stereo with Synthetic Aperture Radar (SAR), which revealed elevations through the 3-D structure, offering a better view than a simple picture.

Credit: Institute of Planetary Sciences

“Instead of looking at the surface of the volcano or the flows, we look at how the volcano deforms the ground around it. In response to the weight of the volcano, the ground around it bends, as if we were bending a plastic ruler,” Megan Russell said. , associate researcher at PSI and principal author of Evidence for a Locally Thinned Lithosphere Associated With Recent Volcanism at Aramaiti Corona, Venus which appears in Journal of Geophysical Research Planets. “The same type of deformation is observed in the curvature of the seabed around the Hawaiian Islands. From this deformation we can infer properties such as the local heat flow to the volcano.”

To go beyond the simple indication of the youngest versus the oldest, it is necessary to use complex computer models to model the deformation of the surface. It is from this modeled deformation that properties such as heat flow can be deduced.

Over time, these types of structures can evolve and the degree of deformation observed indicates the age or youth of a feature and the amount of heat that can flow below the surface.

Russell goes on to explain, “Modeling studies suggest that the shape and topography of this crown indicate that it is also geologically young and that geologically young volcanism is associated with it. ”

This particular structure appears to be unique in the limited Magellan dataset. Only seven other crowns in the 20% of Venus that Magellan studied with SAR have steep-sided volcanoes on or near their fractured ring like the one studied by Russell and Johnson. In addition, the stereo topography data on the feature in this study was of particularly high quality. With three future missions planned for Venus, this team looks forward to exploring this question in more detail in the future. “Fortunately for those of us who were fortunate enough to start our careers working on the Magellan mission, there are now three new missions expected to fly to Venus over the next decade.”

For Johnson, Venus has already played a role for several decades; she worked on her doctorate. in 1984-1989 with a guest investigator on Magellan. For Russell, this job is a great start to his career. This research was carried out while Russell was a gradu

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More information:
MB Russell et al, Evidence for a Locally Thinly Lithosphere Associated With Recent Volcanism at Aramaiti Corona, Venus, Journal of Geophysical Research: Planets (2021). DOI: 10.1029 / 2020JE006783

Provided by the Institute of Planetary Sciences

Quote: New evidence of geologically recent Venusian volcanism (2021, August 10) retrieved August 11, 2021 from

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