Paper No. 5
Presentation Time: 1:30 PM-5:30 PM
ACTIVE MISSION DATA SHOW CONVINCING EVIDENCE OF AMAZINGLY YOUNG GLACIAL PROCESSES AND VARIABLE AGES OF ILD FORMATION IN AN EQUATORIAL CHASM OF VALLES MARINERIS
A new Mars Express Mission anaglyph from Orbit 334 of Central Ophir and Candor Chasmata shows irrefutable evidence of young glacial erosion in east central Candor Chasma. The recently released image (courtesy of MEX HRSC team, FU Berlin, and DLR) shows 2 levels of dark floor material that form cirques at the head of a valley cut into the central dark floor of Candor Chasma; dark floor material is very young and basaltic in composition. Where the canyon merges with another immediately adjacent to the south, the dark material has accumulated in a medial ridge. On the sides of the merged canyons are terminal ridges of dark material. The anaglyph, THEMIS, and MOC images show 2 interior layered deposit (ILD) mounds (downslope from the dams) that have been sheared off at level heights close to those of the dams. Cirques, level shearing of ILD rock materials, and medial/terminal ridges are indisputable evidence of glacial process. That these features form in dark floor materials indicates that the ancient glacier was very young. Another ILD mound, bordering the dark material canyon farther downslope, shows an abrupt flank termination and damming of material, rather than flank scour. A possible terrestrial volcanic analog is the Hegafell hyaloclasitic ridge (tindar) in Iceland, whose eastern flank has a linear termination interpreted as largely unmodified and caused by hyalotuff material banked against a former ice wall that has since melted away. Glacial shearing of some ILDs and confined banking of another ILD indicates that these mounds formed at different times and that the confined ILD may be very young. We are currently exploring deconvolution of THEMIS images into topographic components to attempt to more accurately measure the heights of cirques, shear levels, and medial ridges.