An international team of researchers has found that some of the oldest areas on Venus known as tesserae have strata that appear to be consistent with volcanic activity. The finding could provide insights into the geological history of the enigmatic planet.
Tesserae are tectonically deformed regions on the surface of Venus that are often higher than the surrounding landscape. They make up about 7% of the earth’s surface and, with an age of about 750 million years, are always the oldest feature in their immediate vicinity. A new study appears in geologyThe researchers show that a significant proportion of the stones have stripes that match the stratification.
“There are two general explanations for pebbles – either they are volcanic rock or they are counterparts to the earth’s continental crust,” said Paul Byrne, associate professor of planetary science at North Carolina State University and lead author of the study. “But the stratification that we find on some tessera does not agree with the explanation of the continental crust.”
The team analyzed images of the surface of Venus from NASA’s Magellan mission in 1989, which saw 98% of the planet being imaged by radar through its dense atmosphere. While researchers have studied the pebbles for decades, the stratification of the pebbles was not recognized as widespread before this work. And according to Byrne, this stratification would not be possible if the pebbles were part of the continental crust.
“The continental crust is mostly made up of granite, an igneous rock that is formed when tectonic plates move and water is drawn from the surface,” says Byrne. “But granite does not form layers. If there is a continental crust on Venus, it is under the layered rocks we see.
“Aside from volcanic activity, the other possibility is to create stratified rock in sedimentary deposits such as sandstone or limestone. There is no place on Venus today where these types of rock can form. The surface of Venus is as hot as one self-cleaning ovens and the pressure is equivalent to 900 meters underwater. So the evidence suggests that some parts of the pebbles are made of stratified volcanic rock, similar to that on Earth. “
Byrne hopes the work will help learn more about the complicated geological history of Venus.
“While the data we have now suggests volcanic origins for the pebbles, they would have formed one day if the climates had been very different – maybe even the earth if we could one day sample it and find it sedimentary rocks like, “says Byrne.
“Venus today is hellish, but we don’t know if it has always been like this. Was it once like on Earth but there were catastrophic volcanic eruptions that ruined the planet? Right now we can’t say for sure, but the fact of stratification in the Tesserae limits the possible origins of this rock. “
The research team consisted of scientists from the USA, Great Britain, Turkey, Canada and Russia. The images come from NASA’s Planetary Data System and Astrophysics Data System.
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Paul K. Byrne et al., Venus tesserae show stratified, folded, and eroded rocks. geology (2020). DOI: 10.1130 / G47940.1
Provided by North Carolina State University
Quote: The ancient layered, folded rocks of Venus indicate volcanic origin (2020, September 17) and were layered on September 18, 2020 from https://phys.org/news/2020-09-venus-ancient-layered -volcanic.html retrieved
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