A geoscientist has said that primeval lava flows may have formed Mars ' massive canyons and gorge systems, as water was far too scarce on the red planet to have cut these gigantic valleys into the landscape.
Giovanni Leone, a specialist in planetary volcanism in the research group of ETH professor Paul Tackley, has examined intensively the structure of these canyons and their outlets into the Ares Vallis and the Chryse Planitia, a massive plain on Mars' low northern latitude.
He examined thousands of high-resolution surface images taken by numerous Mars probes, including the latest from the Mars Reconnaissance Orbiter, and which are available on the image databases of the US Geological Survey.
His conclusion was that everything that he observed on those images were structures of lava flows as we know them on Earth.
Leone does not completely rules out water as final formative force.
The Italian volcanologist similarly could find no explanation as to where the massive amounts of water that would be required to form such canyons might have originated.
The explanatory model presented by Leone in his study illustrates the formation history from the source to the outlet of the gorge system. He identifies the volcanic region of Tharsis as the source region of the lava flows and from there initial lava tubes stretched to the edge of the Noctis Labyrinthus. When the pressure from an eruption subsided, some of the tube ceilings collapsed, leading to the formation of a chain of almost circular holes, the 'pit chains'.
When lava flowed again through the tubes, the ceilings collapsed entirely, forming deep V-shaped troughs. Due to the melting of ground and rim material, and through mechanical erosion, the mass of lava carved an ever-deeper and broader bed to form canyons. The destabilised rims then slipped and subsequent lava flows carried away the debris from the landslides or covered it.
"The more lava that flowed, the wider the canyon became," said Leone.
The study has been published in the Journal of Volcanology and Geothermal Research.
