EVIDENCE FOR AN 800 KM DIAMETER IMPACT STRUCTURE IN MERIDIANI PLANUM AND
ASSOCIATED CHANNELS AND BASINS: A CONNECTION WITH THE ORIGIN OF THE HEMATITE
DEPOSITS?
"The overall relief of the structure is very small
(<500m) and the low areas in the structure make up a
series of basins. We have used topographic data and
MOC and THEMIS images to show that the southern
boundary of the hematite area (near the area containing
the strongest hematite signature) was the site of a chain
of paleo-lakes (Fig. 3)."
...
"The connection between the impact structures and
the origin of the hematite could involve precipitation
from hydrothermal fluids associated with the heat from
the impact, either in lakes (e.g. like banded iron formation),
or directly in the observed layered deposits.
Alternatively, the hematite could imply an iron enrichment
process associated with the impact followed
by aqueous processes that enhance or create the observed
surficial hematite signature [e.g. 6]."
http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1414.pdf

Bob Clark