Science & Technology

A mysterious new type of ancient crater lake found on Mars

The spider’s raised ridges across the floor of the Martian crater may have been created by a runoff from a long-lost glacier that once covered the southern highlands of the planet. Credit: NASA

Ancient crater lake in the southern highlands Mars It appears to have been supplied by a glacier outflow, supporting the idea that the red planet had a cold, icy past.

Researchers at Brown University have discovered a previously unknown type of ancient crater lake on Mars. This may reveal clues about the planet’s early climate.

In a study published in Planetary Science Journal, A research team led by Dr. Brown. Student Ben Boatwright describes an unnamed crater with some mysterious features. The crater floor has unmistakable geological evidence of ancient streams and ponds, but no evidence of coves where water may have invaded the crater from the outside, and groundwater may have foamed from below. There is no evidence of sexual groundwater activity.

Water activity Mars crater map

Researchers have mapped a pond where water flows on the floor of the crater. Credit: NASA / Benjamin Boatwright

So where did the water come from?

Researchers conclude that the system was likely supplied by a long-lost Martian glacier outflow. Water flowed into the crater above the glacier. That is, it did not leave a valley as it would have flowed directly to the ground. Water eventually flowed into the lowland Martian floor, leaving geological traces on the bare soil of Mars.

The types of lakes described in this study are very different from other Martian crater lakes. For example, a lake at the crater of Gale or Jezero. NASA Rover is currently under investigation.

“This is a previously unrecognized hydrological system on Mars,” said Boatwright. “In the lake system characterized so far, there is evidence that drainage comes from outside the crater, breaks through the walls of the crater, and in some cases flows out from the other side, but here It’s not what’s happening. Everything is happening in the crater, and it’s very different from what was previously characterized. “

Importantly, Boatlight says Mars provides important clues about Mars’ early climate. There is no doubt that the climate of Mars was once warmer and moist than the frozen deserts of today. But what is less clear is whether Mars had an Earth-like climate with continuous flowing water for thousands of years, or it was almost cold and ice, with a period of momentary warmth and melting. Is it? Early Mars climate simulations suggest that temperatures rarely exceed freezing, but geological evidence of cold and icy conditions is sparse, says Boatlight. This new evidence of ancient glacier action has the potential to change that.

“The cold, icy scenarios were primarily theoretical, which stems from climate models,” says Boatwright. “But the evidence of glacier action seen here helps to bridge the gap between theory and observation. I think that’s a big point here.”

But without signs of an inlet channel where water entered the crater, “the question is,’how did these get here?'” Boatwright said.

Topographic map of the water of the crater on Mars

Topographic maps show raised ridges (dark yellow) and lowlands with water (white). Credit: NASA / Ben Boatwright

To understand that, Boatlight worked with Brown’s advisor and research professor Jim Head. They excluded groundwater activity because the craters did not have a clear subpping channel formed in the groundwater system. These channels are usually displayed as short, chunky channels with no tributaries. This is the exact opposite of the densely branched network of inverting channels observed in craters. Careful examination of the crater wall also revealed a clear set of ridges pointing upwards towards the crater wall. This feature is consistent with the ridges that formed where the glaciers ended and piled up piles of rock debris. In summary, the researchers conclude that the evidence indicates a glacier supply system.

Subsequent investigations have shown that this crater is not the only type.This month Lunar and Planetary Science Conference, Boat light Presentation A study revealing more than 40 additional craters that appear to have relevant features.

Head says these new discoveries may be important in understanding the early Martian climate.

“These models show that the early days of Mars would have been cold and frozen, and now we have some really compelling geological evidence to accompany it.” Head said. “Not only that, this crater provides the criteria needed to start looking for more evidence to test this hypothesis. It’s really exciting.”

See: “Martian Noakia Glacier Paleozous: River Activity and Lake Formation in Closed Watershed Craters and Impact on Mars’ Early Climate”, Benjamin D. Boatlight and James W. Head, March 12, 2021 Planetary Science Journal..
DOI: 10.3847 / PSJ / abe773

A mysterious new type of ancient crater lake found on Mars A mysterious new type of ancient crater lake found on Mars

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