[meteorite-list] Mapping Project Reinforces Belief in Huge Historic Seas on Mars

[Ron Baalke]

NEWS RELEASE FROM THE PLANETARY SCIENCE INSTITUTE

SENT:
June 7, 2010

FROM:
Alan Fischer
Public Information Office
Planetary Science Institute
520-885-5648
fischer at psi.edu

Mapping Project Reinforces Belief in Huge Historic Seas on Mars

A geologic mapping project using NASA spacecraft data offers new evidence 
that expansive lakes existed long ago on Mars.

The research points to a series of sedimentary deposits consistent with what 
would relate to large standing bodies of water in Hellas Planitia located 
in the southern hemisphere of Mars, said by Dr. Leslie Bleamaster, 
research scientist at the Planetary Science Institute.

Fine-layered outcrops around the eastern rim of Hellas have been interpreted 
as a series of sedimentary deposits resulting from erosion and transport 
of highland rim materials into a basin-wide standing body of water, Bleamaster 
said. Hellas basin, more than 2,000 km across and 8 km deep, is the largest 
recognized impact structure on the Martian surface, he said.

The mapping project reinforces earlier research that initially proposed 
Hellas-wide lakes citing different evidence in the west, he said. The new map 
and accompanying map pamphlet may be found at http://pubs.usgs.gov/sim/3096/

"This mapping makes geologic interpretations consistent with previous studies, 
and constrains the timing of these putative lakes to the early-middle Noachian 
period on Mars, between 4.5 and 3.5 billion years ago," he said.

A systematic search of high-resolution images revealed that eastern Hellas 
Planitia, where the fine-layered floor deposits were discovered, is unique
in nature representing a confluence between sedimentary sources and sinks. 
The circum-Hellas highlands represent a significant percentage of the southern 
hemisphere of Mars and have served as a locus for volcanic and sedimentary 
activity throughout Martian geologic time. Hellas Planitia preserves the 
materials shed from these highlands and holds the key to further unraveling 
some of Mars' long held secrets.

"Our mapping and evaluation of landforms and materials of the Hellas region 
from the basin rim to floor provides further insight into Martian climate 
regimes and into the abundance, distribution, and flux of volatiles through 
history," Bleamaster said.

The geologic mapping was published at 1:1,000,000 scale and used Viking Orbiter, 
Thermal Emission Imaging System (THEMIS) infrared (IR) and visible (VIS) 
wavelength, and Mars Orbiter Camera (MOC) narrow-angle images, combined with 
Mars Orbiter Laser Altimeter (MOLA) topographic data, to characterize the 
geologic materials and processes that have shaped this region and was 
supported through NASA's Planetary Geology and Geophysics program.

CONTACT:
Dr. Leslie Bleamaster
Research Scientist
210-437-2805
lbleamas at psi.edu