A recently released set of topographic maps provides new evidence of an ancient northern ocean on Mars. The maps present the strongest case yet that the planet once experienced a sea level rise consistent with an extended warm, humid climate, not the harsh, frozen landscapes that exist today.
Benjamin Cardenas, associate professor of Earth sciences at Penn State and lead author of the study, which was recently published in the Journal of Geophysical Research: Planets.
“It also tells us about the ancient climate and its evolution. Based on these findings, we know that there was a period when it was warm enough and the atmosphere was thick enough to support that much liquid water at one time.”
Cardenas explained that there has been a long debate in the scientific community about whether Mars has an ocean in the lower altitude northern hemisphere. Using topography data, the research team was able to show conclusive evidence of a coastline about 3.5 billion years old with a large sedimentary accumulation, at least 900 meters thick, covering hundreds of thousands of square kilometers.
“The big and new thing that we’ve done in this paper is to think about Mars in terms of its layers and its sedimentary record,” Cardenas said. “On Earth, we plot the history of waterways by looking at sediment that has deposited over time. We call this layer, the idea that water transports sediment and you can measure changes on land by understanding the way that sediment builds up. That’s what we’re done here — but it’s Planet Mars.
The team used software developed by the US Geological Survey to map data from the National Aeronautics and Space Administration (NASA) and the orbital laser altimeter on Mars. They discovered more than 6,500 km of river ridges and grouped them into 20 systems to show that ridges likely eroded river deltas or marine channel belts, remnants of an ancient coastline on Mars.
Elements of the rock formations, such as ridge system thicknesses, elevations, locations and possible sedimentary flow directions helped the team understand the evolution of the area’s ancient geography. Cardenas explained that the area that was once an ocean is now known as the Aeolis Dorsa and contains the largest group of river ridges on the planet.
“The rocks in Aeolis Dorsa capture some wonderful information about the shape of the ocean,” he said. “It was dynamic. Sea level rose dramatically. Rocks were being deposited along their basins at a rapid rate. There was a lot of change going on here.”
Cárdenas explained that on Earth, ancient sedimentary basins contain stratigraphic records of the evolution of climate and life. If scientists wanted to find a record of life on Mars, an ocean as large as the one that covered Ulysses Dorsa would be the most logical place to start.
“The main objective of the Curiosity Mars missions is to search for signs of life,” Cardenas said. “He’s always been looking for water, for traces of habitable life. This is the biggest yet. It’s a giant body of water, fed by sediment coming from the highlands, presumably carrying nutrients. If there were tides on ancient Mars, they would.” They were here, gently fetching water and letting it out. This is exactly the kind of place where ancient Martian life could have developed.”
Cardenas and his colleagues mapped what they identified as other ancient waterways on Mars. An upcoming study in the Journal of Sedimentary Research shows that the many outcrops the Curiosity rover visited were likely sedimentary layers of ancient river rods.
Another paper was published in natural earth sciences It applies an acoustic imaging technique used to view the stratigraphy under the sea floor in the Gulf of Mexico on a Martian basin-like erosion model. The researchers determined that terrain called riverine ledges, found widely across Mars, is most likely ancient river sediments eroded from large basins similar to the Aules Dorsa.
“The layers of the Earth that we are interpreting here are very similar to the layers on Earth,” Cardenas said. “Yes, it seems like a big pretense to say we’ve discovered records of great waterways on Mars, but in reality, these are relatively ordinary layers. It’s geology textbooks once you get to know them for what they are. The interesting part is, of course, is it on Mars? “.
More evidence of water on Mars
Benjamin T. Journal of Geophysical Research: Planets (2022). doi: 10.1029/2022JE007390
Benjamin T. Cardenas et al., Martian landscapes of riverine ridges carved from an ancient sedimentary basin fill, natural earth sciences (2022). DOI: 10.1038 / s41561-022-01058-2
Provided by Penn State University
the quote: Discovering Traces of the Ancient Ocean on Mars (2022, Oct 27), Retrieved Oct 28, 2022 from https://phys.org/news/2022-10-ancient-ocean-mars.html
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