In a study published in the journal Nature Geoscience, planetary researchers used high-resolution images and compositional data captured by orbiters to understand the geology of thousands of kilometer-scale mounds in the lowlands north and west of Mawrth Vallis, a plateau situated on the highland side of Mars’ hemispheric dichotomy boundary.
Two Martian mounds, rising hundreds of meters above the surrounding lowlands, display bright regions rich in clay minerals. Image credit: ESA / TGO / CaSSIS / NASA / JPL / MSSS / Murray Lab.
The research team, headed by London’s Natural History Museum scientist Joe McNeil, discovered that the mounds are the remnants of ancient highlands which retreated by hundreds of kilometers after erosion wore away the terrain billions of years ago.
These actions played a key role in shaping the Martian landscape which divides the planet’s low-lying northern hemisphere from its higher southern hemisphere.
The mounds are made of layered deposits containing clay minerals, formed through water interacting with rock over millions of years.
These clay layers are sandwiched between older, non-clay layers below and younger, non-clay layers above, marking distinct geological events in Mars’ history.
“These mounds are incredibly exciting because they preserve the complete history of water in this region within accessible, continuous rocky outcrops,” Dr. McNeil said.
“They are a prime location for future missions aimed at uncovering whether Mars ever had an ocean and whether life could have existed there.”
The authors also revealed that the mounds are geologically linked to the nearby plains of Oxia Planum, which ESA’s Rosalind Franklin rover is set to launch to in 2028 looking for signs of past and present life.
“Mars is a model for what the early Earth might have looked like, as its lack of plate tectonics means that much of its ancient geology is still in place,” Dr. McNeil said.
“As more missions visit the Red Planet, the more we’ll be able to dig into our own planet’s history to work out how life began.”
“As part of the Natural History Museum’s mission to transform the science of natural history, our research is focussed on providing solutions from and for nature.”
“This study is part of our Planetary Origins and Evolution research theme which explores the origins and systems underpinning the evolution of the Earth, its Moon and planetary systems.”
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J.D. McNeil et al. Dichotomy retreat and aqueous alteration on Noachian Mars recorded in highland remnants. Nat. Geosci, published online January 20, 2025; doi: 10.1038/s41561-024-01634-8
This article is based on a press-release provided by the Natural History Museum, London.
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