HR: 0800h
AN: P41A-0887    [Abstracts]
TI: Inferences on the flow dynamics of fluidized ejecta on Mars from topography
AU: * Barnouin-Jha, O S
EM: olivier.barnouin-jha@jhuapl.edu
AF: U. of Tokyo, PO Box 414 Transdsciplinary Sci. Bldg. 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8561 Japan
AU: * Barnouin-Jha, O S
EM: olivier.barnouin-jha@jhuapl.edu
AF: Johns Hopkins University Applied Physics Laboratory, Johns Hopkins Road, Laurel, MD 20723-6099 United States
AU: Baloga, S
EM: steve@proxemy.com
AF: Proxemy Research Inc, 14300 Gallant Fox Lane Suite 225, Bowie, MD 20715 United States
AU: Glaze, L
EM: lori@proxemy.com
AF: Proxemy Research Inc, 14300 Gallant Fox Lane Suite 225, Bowie, MD 20715 United States
AB: Fluidized ejecta on Mars probably flowed along the surface during their final stages of emplacement. Simple continuum flow models can provide inferences on the fluid dynamics responsible for the observed topographic shapes and morphology of these flows. We compare the solution of such a model in cylindrical geometry to the observed topography of fresh ejecta seen in Lunae Planum, Mars. Comparisons are made with ejecta facies that frequently possess an inner flow with a subtle rampart, separated by a moat and a very pronounced distal contiguous rampart. These are classified as multi-layered (MLE) by the Mars Consortium. We consider the fluid dynamics of two flow types that are likely to describe the emplacement of fluidized ejecta: (1) a basal glide flow where displacement is restricted to a small interface at the base of the flow, and (2) a debris or turbidity flow where motion is dependent on flow thickness to 3/2. The basal glide model describes well granular flows and long-run landslides. A debris flow model could explain the presence of boulders observed at the distal edge of pronounced ramparts of many fluidized ejecta that are reminiscent of the boulders that debris flow often transport at their distal edge. We will present continuum flow solutions for three assumptions: (1) conservation of volume, (2) conservation of mass where volume can change through fragmentation, and (3) entrainment and/or deposition during the final stages of emplacement. Solutions where the volume of the flow is conserved indicate that basal glide best describes the topography of the inner region of the flows (prior to the moat) as well as the distal ramparts.
DE: 5420 Impact phenomena (includes cratering)
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting