A new paper, based on exploration by NASA’s Curiosity Mars rover and reviewed by an astronaut while on the International Space Station (ISS), in what may be the first peer-reviewed science literature, describes how dramatically the geology is changing works on Mars differ from those on Earth.
The paper is part of an ongoing attempt to understand the red planet’s rock cycle – that is, how rock strata are formed, altered and destroyed – which would provide geologists with something of a Rosetta Stone that would enable them to decipher them and to interpret the observations and samples obtained from current and future Mars missions.
The main finding of this particular paper is that the seemingly gentle force of wind erosion drives the process that exposes layered rock strata on Mars. This is in stark contrast to Earth, where layers of rock are exposed by the dynamic combination of tectonic activity pushing up chunks of land and water erosion from rivers cutting into these rocks from top to bottom.
“Erosion work on Mars is mainly driven by the wind, which acts like a feather duster over hundreds of millions to even billions of years. This is very different from Earth, for example, where the extreme ruggedness of the San Gabriel Mountains is caused by torrents of stormwater cutting through the landscape over relatively short geologic timescales,” says John P. Grotzinger, Harold Brown Professor of Geology and Ted and Ginger Jenkins Leadership Chair of the Division of Geological and Planetary Sciences.
Grotzinger is a former Curiosity project scientist and co-author of the Mars Erosion paper published June 8 in the Journal of Geophysical Research: Planets (JGR). The article’s lead author, Jessica Watkins, worked with Grotzinger when she was a postdoctoral fellow at Caltech. In June 2017, Watkins was selected as a NASA astronaut and in April 2022 she was launched into space to work on the ISS. Watkins has finished writing JGR as a postdoctoral fellow at Caltech and submitted it to the journal when she entered astronaut training. By the time the proofs were ready for her to review, she was in space — so she made her final contribution to the paper from low Earth orbit.
The rock cycle on Earth compared to Mars
To visualize the differences between the landforms on Earth and Mars, think of the Himalayan mountains in Asia, home of Mt. Everest. The mountains are being pushed up due to tectonic forces pushing the Indian subcontinent towards Asia, but in doing so the Indus steadily cuts through the rising landmass. The result of both processes is the exposure of layers of rock that geologists use to learn more about the planet’s evolution and history.
Despite observations of small marsquakes by the Mars InSight lander, Mars lacks the tectonic plates that cause most tremors on Earth. Instead, the red planet is formed almost entirely by aeolian, or wind, erosion.
Mars’ atmospheric volume is only 1 percent of Earth’s volume, so one might not expect wind erosion to be that important on the planet. For the last few decades, geologists have argued that the effects of modern winds causing erosion on Mars are very limited. And yet it now appears that wind erosion plays a key role in driving the rock cycle on Mars, certainly during its earlier history 3 billion years ago when the rocks at Gale Crater were formed and then eroded.
Gale Crater is a dry lake 96 miles across just below the equator of Mars. As Curiosity rolled over it, the rover traced the Murray Formation, a 300-meter-thick layer of layered mudstone named in honor of the late Bruce Murray, a Caltech professor of planetary science and former head of the Jet Propulsion Laboratory (JPL). , which Caltech manages for NASA. Mudstone is rock formed from fine-grained mud that has been compressed over time.
Studying Curiosity’s observations, Watkins, Grotzinger and their colleagues found that the Murray Formation – formed from sediments deposited by the water – was being eroded from top to bottom. In addition, the sediments deposited on top show a transverse bedding indicative of ancient sand dunes marching across a desert driven by the wind. Overall, the landscape feels like a humid environment inherited from the Gobi Desert.
“Gale Crater is a spectacular place to document multiple cycles of erosion,” says Grotzinger. “All of this helps us understand how Mars works overall, and will also inform scientists interpreting the Perseverance rover’s observations.”
The article is entitled “Burial and Exhumation of Sedimentary Rocks Revealed by the Base Stimson Erosional Unconformity, Gale Crater, Mars”.
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Jessica A. Watkins et al, Burial and Exhumation of Sedimentary Rocks Revealed by the Base Stimson Erosional Discordance, Gale Crater, Mars, Journal of Geophysical Research: Planets (2022). DOI: 10.1029/2022JE007293
Provided by the California Institute of Technology
Citation: Wind is driving geology on Mars these days (2022, September 13) Retrieved September 13, 2022 from https://phys.org/news/2022-09-geology-mars-days.html
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