Venus’ Ancient Layered, Folded Terrain Points to Volcanic Origin

Planet Venus Magellan Pioneer Composite

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This image is a composite of information from NASA’s Magellan spacecraft and Pioneer Venus Orbiter. Credit: NASA/JPL-Caltech

An global group of scientists has actually discovered that a few of the earliest surface on Venus, referred to as tesserae, have layering that appears constant with volcanic activity. The finding might offer insights into the enigmatic world’s geological history.

Tesserae are tectonically warped areas on the surface area of Venus that are typically more raised than the surrounding landscape. They make up about 7% of the world’s surface area, and are constantly the earliest function in their instant environments, dating to about 750 million years of ages. In a brand-new research study appearing in Geology, the scientists reveal that a substantial part of the tesserae have striations constant with layering.

“There are generally two explanations for tesserae – either they are made of volcanic rocks, or they are counterparts of Earth’s continental crust,” states Paul Byrne, associate teacher of planetary science at North Carolina State University and lead author of the research study. “But the layering we find on some of the tessera isn’t consistent with the continental crust explanation.”

Tellus Tessera Venus

A simulated view from above Tellus Tessera, among the areas on Venus where Byrne et al. recognize the existence of layering. Credit: Image created from NASA’s Magellan objective information.

The group examined pictures of Venus’ surface area from NASA’s 1989 Magellan objective, which utilized radar to image 98% of the world through its thick environment. While scientists have actually studied the tesserae for years, prior to this work the layering of the tesserae hasn’t been acknowledged as prevalent. And according to Byrne, that layering would not be possible if the tesserae were parts of continental crust.

“Continental crust is composed mainly of granite, an igneous rock formed when tectonic plates move and water is subducted from the surface,” Byrne states. “But granite doesn’t form layers. If there’s continental crust on Venus, then it’s listed below the layered rocks we see.

“Aside from volcanic activity, the other way to make layered rock is through sedimentary deposits, like sandstone or limestone. There isn’t a single place today on Venus where these kinds of rocks could form. The surface of Venus is as hot as a self-cleaning oven and the pressure is equivalent to being 900 meters (about 985 yards) underwater. So the evidence right now points to some portions of the tesserae being made up of layered volcanic rock, similar to that found on Earth.”

Byrne hopes that the work will assist to clarify more of Venus’ complex geological history.

“While the data we have now point to volcanic origins for the tesserae, if we were one day able to sample them and find that they are sedimentary rocks, then they would have had to have formed when the climate was very different – perhaps even Earth-like,” Byrne states.

“Venus today is hellish, but we don’t know if it was always like this. Was it once like Earth but suffered catastrophic volcanic eruptions that ruined the planet? Right now we cannot say for certain, but the fact of the layering in the tesserae narrows down the potential origins of this rock.”

The research study group consisted of researchers from the U.S., the U.K, Turkey, Canada and Russia. Images originated from NASA’s Planetary Data System and Astrophysics Data System.

Reference: “Venus tesserae feature layered, folded, and eroded rocks” by Paul K. Byrne, Richard C. Ghail, Martha S. Gilmore, A.M. Celâl Şengör, Christian Klimczak, David A. Senske, Jennifer L. Whitten, Sara Khawja, Richard E. Ernst and Sean C. Solomon, 4 September 2020, Geology.
DOI: 10.1130/G47940.1