HR: 1340h
AN: P23B-0193    [Abstracts]
TI: Generation of meltwater by dike intrusion on Mars
AU: * Ogawa, Y
EM: yoshiko@eps.berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, Univ. of California Berkeley, Dept. of Eath and Planetary Sciecnce, 307 McCone Hall, Berkeley, CA 94720-4767 United States
AU: Manga, M
EM: manga@seismo.berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, Univ. of California Berkeley, Dept. of Eath and Planetary Sciecnce, 307 McCone Hall, Berkeley, CA 94720-4767 United States
AB: The morphology and location of outflow channels on Mars indicate a subsurface origin of the water. However, the origin and processes, that can provide the large inferred discharge, is not well understood. Following previous studies, we hypothesize that dike intrusion played a significant role. The near-simultaneous discharge of magma and water, e.g., at Athabasca Valles, suggest a causal relationship between magmatism and flooding at least in some setting. We thus quantify, using numerical models the conditions, the conditions under which dikes may permit large discharges of water. We perform 2-D numerical simulations of the amount and distribution of meltwater adjacent to a cooling dike to test the hypothesis. We extend HYDROTHERM code developed by the USGS (Hayba and Ingebritsen, 1997) and include the effects of the phase transition between ice and water. We thus account for both boiling and freezing. The interaction between magma and frozen ground is assumed to occur at depths between several kilometers and a few hundred meters depth,. At the depths, boiling may occur without direct sublimation. We evaluate the melting process of the permafrost layer by estimating the following: (1) How much meltwater can be generated? (2) What is the pattern of hydrothermal circulation?, and (3) How fast does the dike cool? We vary the volume an thickness of the dike, and the permeability of the crust. We find that to generate large floods requires a large subsurface reservoir of pressurized water - melting by dikes alone is insufficient to create large floods.
DE: 5220 Hydrothermal systems and weathering on other planets
DE: 5416 Glaciation
DE: 5419 Hydrology and fluvial processes
DE: 5422 Ices
DE: 5480 Volcanism (6063, 8148, 8450)
SC: Planetary Sciences [P]
MN: Fall Meeting 2005