Rocks shows that Mars once felt like Iceland

Once upon a time, seasons in Gale Crater probably felt something like that in Iceland. But no one was there to merge more than 3 billion years ago.

The ancient Mars crater is the focus of a study by scientists from Rice University comparing the data of the Curiosity rover with places on earth where similar geological formations have experienced weathering in different climatic substances.

Iceland’s basalt terrain and cool weather, with a temperature of less than 38 degrees Fahrenheit, appear to be the closest analogue to ancient Mars. The study determined that temperature had the greatest impact on the way rocks formed from sediment deposited by ancient Martian currents were weathered by the climate.

The study by postdoctoral fellow Michael Thorpe and Mars geologist Kirsten Siebach van Rice and geoscientist Joel Hurowitz of New York State University in Stony Brook sought to answer questions about the forces that sand and mud in the ancient multi-bed.

Data that Curiosity has collected during its travels since landing on Mars in 2012 contains details about the chemical and physical conditions of mudstones formed in an ancient lake, but the chemistry does not show the climatic conditions when the sediment eroded downstream. For that, the researchers had to search for similar rocks and soils on earth to find a correlation between the planets.

The study published in JGR Planete takes data from known and varying conditions in Iceland, Idaho and around the world to see what best fits those observing and observing the rover in the crater that includes Mount Sharp.

The crater once contained a lake, but the climate that allowed it to fill water is a long-running debate. Some argue that early Mars was hot and wet, and that rivers and lakes were frequently present. Others think it was cold and dry and that glaciers and snow were more common.

“Sedimentary rocks in Gale Crater instead provide an outline of a climate likely to fall between these two scenarios,” Thorpe, now a Mars monster scientist, told NASA Johnson Space Center contractor Jacobs Space Exploration Group . “The ancient climate was probably icy, but apparently also supported liquid water in lakes for long periods.”

The researchers were surprised that after more than 3 billion years, there was so little weathering of rocks on Mars, that the ancient Martian rocks were comparable to the Icelandic sediments in a river and more.

“On Earth, the sedimentary rock figures do a fantastic job of aging over time using chemical weathering,” Thorpe noted. “On Mars, however, we see many young minerals in the mud rocks that are older than any sedimentary rocks on earth, indicating that the weathering was limited.”

The researchers studied sediments from Idaho and Iceland directly and compiled studies of similar basalt deposits from different climatic regions around the world, from Antarctica to Hawaii, to limit the climatic conditions they thought were possible on Mars when the water flowed to the Gale Crater. .

“The earth provided us with an excellent laboratory in this study, where we were able to use a variety of places to see the effects of different climate variables on the weathering, and the average annual temperature had the strongest effect for the types of rocks in Crazy Crater, “he said. Siebach, a member of the Curiosity team that will be a perseverance operator after hitting the new lander in February. “The climate range on Earth has enabled us to calibrate our thermometer to measure the temperature on ancient Mars.”

The composition of sand and mud in Iceland was the best agreement with Mars, based on analysis by the Standard Chemical Change Index (CIA), a basic geological tool used to deduce the previous climate from chemical and physical weathering of a monster.

“As water flows through rocks to erode and weather them, it dissolves the most soluble chemical components of the minerals that make up the rocks,” Siebach said. ‘On Mars we have seen that only a small fraction of the elements that dissolve the fastest are lost from the mud with respect to volcanic rocks, although the mud has the smallest grain size and is usually the most weathered.

“It really limits the average annual temperature on Mars when the lake was present, because if it had been warmer, more of the elements would have been washed away,” she said.

The results also indicated that the climate shifted over time from Antarctic conditions to becoming more Icelandic while fluvial processes continued to deposit sediments in the crater. This shift shows that the technique can be used to detect climate change on ancient Mars.

While the study focused on the lowest, oldest part of the more sediments that investigated curiosity, other studies also indicated that the March climate was likely to change and become drier over time. “This study provides one way to interpret the trend more quantitatively compared to the climate and environment we know well on earth today,” Siebach said. “Similar techniques can be used through perseverance to understand the ancient climate around the landing site at the Jezero crater.”

In parallel, climate change, especially in Iceland, could shift the places on earth that are best suited to understand the past on both planets, she said.

Siebach is an Assistant Professor of Earth, Environmental and Planetary Sciences at Rice. Hurowitz is an associate professor of earth sciences at Stony Brook.