Clay sediments present in the valleys and alluvial fans of Mars suggest that liquid water was present on Mars during different periods, in a time frame of about 1.3 billion years. At that time, the conditions of habitability would have been those indicated for the emergence of life.
Scientists at the Planetary Science Institute (PSI) in Arizona, USA, have identified clayey sediments in the northern Ladon Valles on Mars that point to the long-term presence of water. The researchers believe that water flowed in that area from about 3.8 billion years ago to about 2.5 billion years ago, a big part of martian history.
During that period, the living conditions would have been conducive to the development of some form of life. According to a press release, the researchers believe the clays originally formed around higher ground above the Ladon Basin, before being eroded by water channels and carried downstream to a lake in the Ladon Basin. and northern Ladon Valles.
According to the team, which recently published two scientific articles in the journal Icarus, the most recent flow of water would have manifested itself along the southwestern Ladon Basin. This entire sector is part of a vast region full of craters, called Margaritifer Terra. Meanwhile, the deposits discovered in that area match features found elsewhere on Mars: the Eberswalde delta, just south of the region covered by the new studies.
Video: A region on Mars may have been habitable for a large part of Martian history. Credit: Planetary Science Institute / YouTube.
clay and life
The presence of clays indicates a favorable environment for life, because clays form and remain stable in conditions of neutral pH, where water persists in the long term. This minimizes evaporation to form other minerals such as sulfates, which could lead to faster water loss.
The two studies, led by Catherine Weitz and Alexander Morgan, conclude that Mars had liquid water in the form of rivers for a prolonged period, although at the same time they agree that the red planet did not remain wet throughout this cycle, about 1.3 billion years old. The conditions that allowed liquid water may have been episodic, perhaps driven by changes in Mars’ motions and dynamics, such as its orbital eccentricity or volcanic activity.
In recent years, increasing evidence has accumulated that substantial amounts of liquid water they continued to erode the Martian surface for hundreds of millions of years, creating landforms such as river deltas and alluvial fans. The researchers found that alluvial fans are found at lower elevations than older valley networks, suggesting that stable liquid water became restricted to lower, warmer regions as Mars cooled and dried.
Large amounts of liquid water
A lots of Martian alluvial fans they are huge, stretching up to 40 kilometers across, indicating that their formation required prodigious amounts of moving liquid water. One particularly interesting detail about the Martian fans is that many formed later than the valley networks, which for decades have been considered the strongest evidence for surface water on early Mars.
Alluvial fans are landforms that form when a river deposits sediment at the base of a mountain front. These features are very prominent in the southwestern United States: Los Angeles, Las Vegas, or Phoenix are built on alluvial fans. In addition to those discovered on Mars, they have also been identified alluvial fans on Titan, Saturn’s moon.
Clay sediments derived from fluvial activity in and around Ladon basin, Mars. Catherine M. Weitza et al. Icarus (2022). DOI:https://doi.org/10.1016/j.icarus.2022.115090
The global distribution and morphologic characteristics of fan-shaped sedimentary landforms on Mars. Alexander M. Morgan et al. Icarus (2022). DOI:https://doi.org/10.1016/j.icarus.2022.115137