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How were the two Megatsunamis that swept the shores of Mars

How were the two Megatsunamis that swept the shores of Mars


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The ancient coastlines of the ocean that occupied the northern plains of Mars were ripped apart by two megatsunamis about 3.4 billion years ago. This is reflected in an international study based on thermal images of the northern plains of this planet, where enormous sedimentary deposits appear that could have been located by these two gigantic tsunamis. The work is published this week in Scientific Reports.

"Our work confirms the presence of stable and extensive oceans on Mars, at least until 3,000 million years ago", underlines Sinc Alberto G. Fairén, co-author of the work and researcher at the Center for Astrobiology (CAB) in Madrid and the University Cornell in New York.

"Furthermore," he adds, "we confirmed that the oceans would have been very cold. In other words, you shouldn't imagine beaches like those of Levante on primitive Mars, but rather an environment more similar to the Arctic Glacial Ocean ”. The thermal images show icy lobes, important from an astrobiological point of view, as they are probably frozen brines from the ancient Martian ocean.

The new discovery also offers a simple answer to a question scientists have been asking for decades: Why aren't coastlines recognized if there really was an ocean on Mars some 3.4 billion years ago?

“We offer a new piece that could help solve this puzzle: the deposits generated by the tsunamis could modify the coastline of the early oceans of Mars, contributing to the uneven elevation - says Fairen -, although there are other possibilities, such as the presence of immense glacial fields on the coastline, the flow of water from the highlands to the lowlands or changes in the thermal structure of the lithosphere. "

The study has documented the two tsunami events separated by a period of a few million years, during which the ocean level receded and the climate became much colder.

According to the authors, the two megawaves would have been caused by the impact of meteorites, which could have produced craters of about 30 kilometers in diameter. Due to the magnitude of the phenomenon, scientists rule out that they were caused by earthquakes. Furthermore, it is not clear that Mars ever had a mobile lithosphere with the ability to generate such large earthquakes.

The oldest tsunami swept away blocks of rock more than 10 meters in diameter, leaving large tracts of chaotic deposits and channels dug out as the flood receded. The subsequent tsunami, for its part, generated ice-rich lobes, some 250 km long.


Image of the northwestern region of Arabia Terra taken by NASA's Mars Reconnaissance Orbiter in 2008, and a digital elevation model of Mars. / NASA / USGS / ESA / DLR / FU Berlin G.Neukum

The coastline was destroyed by both events, making it difficult for researchers to recognize it in studies conducted to date. However, the analysis of new very high resolution images has made it possible to identify the morphologies and characteristic deposits of these tsunamis.

According to Mario Zarroca and Rogelio Linares, geologists from the Autonomous University of Barcelona (UAB) who have also participated in the work, “our results indicate that the waves caused by the tsunamis could have reached 120 m in height on the coastline, penetrating on the continent distances of up to 200 and 700 km ".

The smooth topography of the northern lowlands of Mars, as well as the particular conditions of wave propagation under a gravity much lower than that of the Earth, would have caused the flood distances to be enormous, compared to those observed on Earth. .


Height and penetration in the continent of a Martian tsunami considering a wave of 120 meters high, and recreation of the flood that would cause in the coasts of Barcelona. / UAB

The researchers highlight the importance of being able to obtain samples of the ice-rich lobes caused by the second tsunami in future space missions. “These materials are relatively close to the Mars Pathfinder landing site. The fact that many of the lobes have well-defined boundaries and that they still retain their characteristic morphology suggests that they probably still contain frozen brine from the ancient ocean and that they could have preserved their primary composition ”, explains José Alexis Palmero Rodríguez, the lead author, from the Planetary Science Institute in the USA.

Frozen lobes where to look for life

Cold, salty waters can provide a refuge for life in extreme environments, as dissolved salts may help keep the water liquid. "Therefore, if life existed on Mars, these icy lobes hundreds of kilometers long are good candidates for looking for biomarkers," adds Fairén.

The European Space Agency's ExoMars rover will land in 2020 not far from these lobes, and will have an optimal suite of instruments for searching for life in the tsunami sediments.

For the moment, this study has been carried out with mapping techniques based on the analysis of the images taken by the CTX and HiRISE cameras of the Mars Reconaiser Orbiter, infrared thermal images of the THEMIS instrument of the Mars Odyssey and the MOLA elevation model of the Mars mission. Global Surveyor.

Spectacular images of streams of ice and material sliding over a frozen Canadian river, a terrestrial analogy of what could have happened on Mars.
Cover photo: The color-coded elevation model of the study area shows the two proposed coastlines in the ocean of Mars from about 3.4 billion years ago. On the right, the areas covered by tsunamis. / Alexis Rodriguez


Video: If You See a Tsunami, Never Do Certain Things! (June 2022).


Comments:

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  2. Dean

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  3. Codrin

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