Boundary layer models of Martian hydrothermal systems Kate Craft 11/2/2007

Deep Sea Vents Photo Credit: Peter Etnover Photo taken by I.R. Jonasson, 1992

Magma Chamber Hydrothermal Systems on Mars Gulick, 1998 Magma intrusion heats up surrounding groundwater Newsom, 1980 Impact Crater

NASA/JPL Martian gullies New gulley discovered in 2005 Gulick, 1998 Geomorphology Gullies Stepped fans Outflow Channels Oceans

Basic Model y T  = 4  C V  = 0 Porous medium full of water Vertical, Impermeable, Heated Wall T w = 500  C g u v x MAGMA q = 0, impermeable Assumptions Single phase flow (water always in liquid phase) Wall at constant temperature Water source is existing groundwater

Governing Equations Can solve numerically, but also know general behavior through scaling law Conservation of Mass Conservation of Momentum Conservation of Energy  y x Bejan, 1995  m =density of mixed rock/fluid and medium;  f = density of fluid

y x, m 0 4km 2km Numerical Solutions Boundary Layer Integrate across  to get heat and mass flow outputs T reaches ~ T  v reaches ~ 0 Temperature and Velocity Profiles

Heat Output Results to 1δ at heights of 1 and 10 km above the bottom of the magma chamber captures more than 99% of the heat flux that occurs out to 3 

at heights of 1 and 10 km above the bottom of the magma chamber which captures greater than 95% of the volume flux that occurs out to 3  Volume Flux to 1δ

Comparison to Martian Hydrographs Kraal, km long dike with a depth of ~ 5 km injected into a highly permeable rock would transport ~10 km 3 /yr of fluid Gullies Stepped Fans Outflow channel Northern Ocean Drainage Networks Ma’adim Vallis Esberwalde Delta Estimated formation time range (years) Estimated volume water (km 3 )

Conclusions & Future Work Permeability primarily controls the mass and heat flux Total amount of heat and mass delivered depends upon the lifetime of the intrusion For given assumptions output volume can create gullies on the order of years Future work Use FISHES program to consider: Time dependence Two phase saltwater flow Brine formation The high permeabilities of Martian regolith

References Bejan, A., 1995, Convection Heat Transfer 2 nd ed., 639 p., Wiley, New York. Gulick, Virginia. “Magmatic intrusions and a hydrothermal origin for fluvial valleys on Mars.” Journal of Geophysical Research, Vol. 103: E8, Aug Newsom, H. E., 1980, Hydrothermal alteration of impact melt sheets with implications for Mars, Icarus, v. 44, p Correspondence with Dr. Erin Kraal, Geological Sciences Department, Virginia Tech University, Blacksburg, VA, 2007.