September 14, 2013
Ice Lake Collapse Led To Aram Chaos On Mars
April Flowers for redOrbit.com - Your Universe Online
The catastrophic melting and outflow of a buried ice lake formed the lumpy, bumpy floor of an ancient impact crater on Mars known as Aram Chaos. Satellite observations of the 173 mile wide and 2.5 mile deep crater were combined with models of the ice melting process and resulting catastrophic outflow for a new study presented at the European Planetary Science Congress (EPSC) at UCL in London by Michael Roda of the Utrecht University.Chaotic terrains are distinctive to Mars. These enigmatic features stretch up to hundreds of miles across. Until now, the mechanism by which they are formed has been poorly understood by scientists.
"About 3.5 billion years ago, the pristine Aram impact crater was partly filled with water ice that was buried under a two-kilometer (1.2 mile) thick layer of sediment. This layer isolated the ice from surface temperatures, but it gradually melted over a period of millions of years due to the heat released by the planet. The sediment overlying fluid water became unstable and collapsed," said Roda.
Four times the volume of Lake Baikal, the largest freshwater lake on Earth, the resulting massive expulsion of 24,000 cubic miles of liquid water carved a valley 6 miles wide and 1 mile deep in about one month. A chaotic pattern of blocks was left in the Aram crater.
"An exciting consequence is that rock-ice units are possibly still present in the subsurface. These never achieved the melting conditions, or melted only a lower thin layer, insufficient to result in a full collapse event. Buried ice lakes testify of Mars rapidly turning into a cold, frozen planet, but with lakes buried in the subsurface. These lakes could provide a potentially favorable site for life, shielded from hazardous UV radiation at the surface," said Roda.
Roda was joined by colleagues from Utrecht University and Jacobs University Bremen in completing this study.