HR: 1340h
AN: P13A-0986    [Abstracts]
TI: Formation of Valles Marineris and Associated Outlfow Channels by Catastrophic Dewatering of Evaporite Deposits
AU: * Montgomery, D R
EM: dave@ess.washington.edu
AF: Quaternary Research Center, Box 351310 University of Washington, Seattle, WA 98195-1310 United States
AU: Gillespie, A
AF: Quaternary Research Center, Box 351310 University of Washington, Seattle, WA 98195-1310 United States
AB: Geological mapping based on topographic analysis of Mars Orbiter Laser Altimeter (MOLA) data, together with photointerpretation of Mars Orbiter Camera (MOC) images, and thermodynamic and heat-flow considerations lead to a new hypothesis for the formation of Valles Marineris and the associated outflow channels through catastrophic dewatering of ancient evaporite deposits. MOLA transects across Valles Marineris reveal that the valley is located at the crest of a 2-km-high topographic bulge on the flank of the much larger Tharsis Rise. The Interior Layered Deposits (ILDs) within Valles Marineris unconformably underlie, and therefore would have been heated by, Hesperian age lava flows, as well as from below by insulation by the Hesperian flows and an increased geothermal gradient due to development of the Tharis Rise. The ILDs are now thought on the basis of spectroscopic data to contain hydrous sulfate salts. The estimated range of increased temperatures predicts the potential to dehydrate $>$km-thick sections of gypsum or epsomite in reactions that would trigger volumetric expansion sufficient to account for the topographic bulge and catastrophically release tremendous amounts of over-pressured water.
DE: 5415 Erosion and weathering
DE: 5418 Heat flow
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting