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Traces
of recent water on Mars: Liquid water on Mars as recently as 200,000 years ago
Traces
of recent water on Mars: Liquid water on Mars as recently as 200,000 years ago
Date:
April 25,
2014
Source:
University of Gothenburg
Summary:
New research has shown that there was liquid water on
Mars as recently as 200,000 years ago. The southern hemisphere of Mars is home
to a crater that contains very well-preserved gullies and debris flow deposits.
The geomorphological attributes of these landforms provide evidence that they
were formed by the action of liquid water in geologically recent time.
.........................
New research has shown that there was liquid water on Mars
as recently as 200,000 years ago. The results have been published in the
international scientific journal Icarus.
"We
have discovered a very young crater in the southern mid-latitudes of Mars that
shows evidence of liquid water in Mars' recent past" says Andreas Johnsson
at the University of Gothenburg.
The southern
hemisphere of Mars is home to a crater that contains very well-preserved
gullies and debris flow deposits. The geomorphological attributes of these
landforms provide evidence that they were formed by the action of liquid water
in geologically recent time.
Evidence of
liquid water
When
sediment on a slope becomes saturated with water, the mixture may become too
heavy to remain in place, leading to a flow of debris and water as a
single-phase unit. This is called a debris flow. Debris flows on Earth often
cause significant material destruction and even human casualties, when they
occur in built-up areas. During a debris flow, a mixture of stones, gravel,
clay and water moves rapidly down a slope. When the sediment subsequently
stops, it displays characteristic surface features such as lobate deposits and
paired levees along flow channels.
It is these
landforms that Andreas Johnsson has identified on Mars. The research group has
been able to compare the landforms on Mars with known debris flows on Svalbard
with the aid of aerial photography and field studies. The debris flows on Mars
provide evidence that liquid water has been present in the region.
"Our
fieldwork on Svalbard confirmed our interpretation of the Martian deposits.
What surprised us was that the crater in which these debris flows have formed
is so young," says Andreas Johnsson of the Department of Earth Sciences,
University of Gothenburg.
After the
ice age
Crater
statistics allowed Andreas Johnsson and his co-authors to determine that the
age of the crater to be approximately 200,000 years. This means that the crater
was formed long after the most recent proposed ice age on Mars, which ended
around 400,000 years ago.
"Gullies
are common on Mars, but the ones which have been studied previously are older,
and the sediments where they have formed are associated with the most recent
ice age. Our study crater on Mars is far too young to have been influenced by
the conditions that were prevalent then. This suggests that the
meltwater-related processes that formed these deposits have been exceptionally
effective also in more recent times," says Andreas Johnsson, principal
author of the article.
Impact in
wet ground
The study
crater is situated in the mid-latitudes of Mars' southern hemisphere,
superposed on what is known as the rampart ejecta of a nearby larger
crater. A rampart ejecta display a "flowerlike" form around
the host crater, and scientists have interpreted this as being the result of an
impact in wet or ice-rich ground.
"My
first thought was that the water that formed these debris flows had come from
preserved ice within the rampart ejecta. But when we looked more closely, we
didn't find any structures such as faults or fractures in the crater that could
have acted as conduits for the meltwater. It is more likely that the water has
come from melting snow packs, when the conditions were favorable for snow formation.
This is possible, since the orbital axis of Mars was more tilted in the past
than it is today," says Andreas Johnsson.
Story
Source:
The above
story is based on materials provided by University of Gothenburg. Note: Materials may be
edited for content and length.
Journal
Reference:
- A. Johnsson, D. Reiss, E. Hauber, H. Hiesinger, M. Zanetti. Evidence for very recent melt-water and debris flow activity in gullies in a young mid-latitude crater on Mars. Icarus, 2014; 235: 37 DOI: 10.1016/j.icarus.2014.03.005
Cite This
Page:
University of Gothenburg.
"Traces of recent water on Mars: Liquid water on Mars as recently as
200,000 years ago." ScienceDaily. ScienceDaily, 25 April 2014.
<www.sciencedaily.com/releases/2014/04/140425075025.htm>.
