The 25 km high Olympus Mons volcano on Mars may have once been located in the middle of a vast ocean.
Olympus Mons volcano on the surface of Mars. Photo: CNRS
When Mars was young and wet billions of years ago, the massive volcano Olympus Mons may have looked like Stromboli or Savai'I on Earth, but on a much larger scale. A new analysis published in the journal Earth and Planetary Science Letters points out many similarities between Olympus Mons and active volcanic islands on Earth, providing further evidence of Mars' watery past, Science Alert reported on July 27.
According to a research team led by geoscientist Anthony Hildenbrand of the University of Paris-Saclay in France, the upper rim of the 6-kilometer-high cliff surrounding the Olympus Mons volcano was likely formed by lava flowing into liquid water when the structure was an active volcanic island around the late Noachian and early Hesperian periods.
Olympus Mons is a 25-kilometer-high shield volcano that stretches across an area the size of Poland. It is not only the largest volcano in the Solar System, but also the tallest mountain. However, its base does not meet the ground as a gentle slope. Instead, at around 6 kilometers high, a steep cliff surrounds much of its perimeter, plunging straight down to the surface below. The origin of this cliff remains a mystery.
Today, Mars is barren and dusty. Water on the planet’s surface exists only as ice, there are no flowing rivers, and there are no oceans that cover vast basins and craters. But researchers are finding increasing evidence that Mars once had plenty of liquid water. Gale Crater, where Curiosity is currently working, may have been a vast lake billions of years ago.
Hildenbrand and his colleagues used the data to reconstruct the landscape around Olympus Mons. They looked at similar shield volcanoes on Earth. In particular, they studied three volcanic islands: Pico Island in Portugal, Fogo Island in Canada, and Hawaii in the United States. The team found that the coastlines of these islands had steep cliffs, similar to those surrounding Olympus Mons. On Earth, such cliffs result from changes in the viscosity of lava due to temperature differences when it transitions from air to water. So the researchers speculate that Olympus Mons was once a volcanic island surrounded by liquid water.
According to the team, the height of the steep cliffs could be the sea level of the lost ocean. The lava flow period 3-3.7 billion years ago is when the ocean existed. "Future sample-collecting spacecraft or autonomous robots could date some sites on Olympus Mons, which hold great research potential," Hildenbrand and his colleagues concluded.
An Khang (According to Science Alert )
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