Volcanism on Mars
Major Sites of Volcanism
Overview
Mars has the largest
shield volcanoes
in the solar system. It also has a
wide range of other volcanic features. These include large
volcanic cones,
unusual
patera structures,
mare-like volcanic plains, and a number of
other smaller
features.
However, volcanic features are not common. There
are less than 20 named volcanoes on Mars, and only 5 of these are giant
shields. Also, volcanism occurs mostly within three regions. Even the
mare-like plains cluster near these regions. The main cluster of volcanoes
and lavas is in Tharsis. A much smaller cluster of three volcanoes lies
in Elysium. Lastly, a few paterae are near the Hellas impact basin.
Differences from Moon
Age
Like the Moon, volcanism on Mars is very old. The mare-like plains
on Mars are the same age as the lunar mare, roughly 3 to 3.5 billion years
old. However, volcanism lasted much longer on Mars than on the Moon. It
also seems to have changed over time. Volcanism in the highland paterae
and mare-like plains on Mars stopped 3 billion years ago, but some of the
smaller shields and cones erupted only 2 billion years ago. The giant
shield volcanoes are even younger. These volcanoes formed between 1 and 2
billion years ago. The youngest lava flows on Olympus Mons are only 20 to
200 million years old. These flows are very small, however, and they
probably represent the last gasp of martian volcanism. Thus, the odds of
finding an active volcano on Mars today are very small.
Setting
Like the Moon, Mars shows no sign of
plate tectonics. It has no long mountain chains, and there is no clear
global pattern to the volcanism. Over half of Mars is heavily cratered
like the lunar farside. Unlike the Moon, however, most martian volcanism
lies outside large impact basins. Instead, the mare-like plains are mostly
near the largest volcanoes. These plains also are not limited to the
lowest elevations. Indeed, some lava plains are much higher than the
cratered uplands. Lava plains may lie at lower elevations as well.
However, thick layers of dust and sediment cover both the Northern
Lowlands and the large basin floors. These layers reflect a long history
of winds, glaciers and flood events. They also hide any volcanism that may
have occurred in the low areas on Mars.
Processes
The concentration and duration of volcanism into these two
regions are attributed to the evolution of a long-lived mantle hotspot.
Links
More Mars Volcano Information can be found at the "Geology of Mars" website curated by Albert T. Hsui, University of Illinois at Urbana-Champaign.
As well as:
Mars
http://seds.lpl.arizona.edu/nineplanets/nineplanets/mars.html
Mars Today.com
http://marstoday.com/
NASA’s Mars Exploration Program
http://mars.jpl.nasa.gov
Mars Global Surveyor
http://mars.jpl.nasa.gov/mgs/
NASA Human Spaceflight
http://spaceflight.nasa.gov/mars/
Images of Volcanoes
To VolcanoWorld