Over the past two decades, Martian rovers have collected a lot of information about the Red Planet. For geologists, the data of the chronologically last spacecraft - Curiosity, which arrived on Mars on August 6, 2012, are of the greatest interest.
The rover was landed on the planet's surface in Gale Crater, a large meteorite crater approximately 154 km in diameter. Scientists believe that it originated about 3.5 billion years ago, and its depth gives hope for the possibility of studying sedimentary strata once exposed by a meteorite.
Apparently, these hopes are not unfounded. To date, the rover has traveled about 20 kilometers and studied sedimentary rocks with a thickness of about 400 meters. They are between 3.7 and 4.1 billion years old, says Ezat Heydari of Jackson University, Mississippi.
Heydari and his colleagues used sedimentary data to interpret geological processes that took place billions of years ago on Mars. The results were presented at the annual meeting of the Geological Society of America in Indianapolis, Indiana.
Within this 400-meter section, the researchers identified four different types of rocks and, in their opinion, they are all somehow related to water.
One of the layers, called the Hummocky Plain Unit, consists of granular deposits, the size of individual stones in which reaches 20 centimeters. In the same thickness, the rover managed to photograph blocks of about four meters in size. On Earth, if the stones are properly rolled, this would be interpreted as moraine deposits left by the glacier. On Mars, it is more difficult to draw conclusions about the state of the stones, so so far it is assumed that extensive glaciers were not there. But there was liquid water, and if it could move four-meter blocks, then there was a lot of it.
Martian sedimentary rocks from Gale Crater. In appearance indistinguishable from terrestrial river sediments.
In addition, scientists from the Heydari group drew attention to the Martian relief, the features of which, in their opinion, indicate the presence of powerful streams of water, up to 10-20 meters deep. Taken together, this apparently means that, at least sometimes, in the past, there was a lot of liquid water on Mars.
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Heydari says the sedimentary rocks found in Gale Crater may have originated in conditions geologically identical to those that existed on Earth in the Pleistocene (2 million years to 12,000 years ago), with large-scale glaciation and violent floods.
For details, see the report of the American Geological Society.
Sergey Sysoev