Sedimentary mineral deposits found on the surface of Mars may have been left by an ancient sea 3.5 billion years ago. New results from China’s Tianwen-1/Zhurong mission suggest the presence of features consistent with a coastline in the southern Utopia Planitia and provide further evidence for the existence of a short-lived ocean early in the planet’s history.
The Zhurong landing site. Image credit: Wu et al., doi: 10.1038/s41598-024-75507-w.
“The hypothesis of the existence of a Martian ocean in the northern lowlands remains an intriguing open question about the early stages of the planet’s evolution,” said Dr. Bo Wu of the Hong Kong Polytechnic University and colleagues.
“The existence of the ocean may have significantly influenced the climate and atmosphere of early Mars and left geological records of its presence.”
“China’s Mars rover Zhurong, onboard the Tianwen-1 probe, successfully landed in southern Utopia Planitia on Mars in May 2021.”
“This region has long been hypothesized to be a part of an ancient ocean that once covered the northern lowlands.”
In the study, Dr. Wu and co-authors analyzed data retrieved from the Tianwen-1 orbiter and the Zhurong rover to provide estimates of the surface ages and mineral compositions of material found in southern Utopia Planitia.
They identified distinct geomorphological features such as troughs and sediment channels consistent with a nearshore zone, suggesting a possible formation event involving flooding approximately 3.68 billion years ago.
In this scenario, a short-lived frozen ocean formed a coastline, with the ocean surface likely freezing and disappearing approximately 3.42 billion years ago.
“Different types of water-related geomorphological features were separated by specific topographic contours, suggesting different types of marine environments,” the researchers said.
“The area was subdivided into a foreshore highland-lowland transition unit, a shallow marine unit and a deep marine unit.”
“In situ observations including sedimentary deposit rocks, water-related lamination features, and subsurface sedimentary layers, also indicate past water activities.”
“Results suggested an evolution scenario of the nearshore zone in southern Utopia: (i) flooding of the Utopia Planitia in Late Noachian around 3.65-3.68 billion years ago reached the foreshore unit; (ii) formation of the shallow and deep marine units after the flooding was completed by about 3.5 and 3.42 billion years ago in Early Hesperian, respectively; (iii) gradual loss of subsurface volatiles during the Amazonian epoch.”
The study appears in the journal Scientific Reports.
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B. Wu et al. 2024. A probable ancient nearshore zone in southern Utopia on Mars unveiled from observations at the Zhurong landing area. Sci Rep 14, 24389; doi: 10.1038/s41598-024-75507-w
