Models of Martian Hydrothermal Systems and Implications for Geomorphology

Introduction: Many geomorphic features on the surface of Mars, such as gullies, fans, paleolakes, outflow channels, and deltas, were likely caused by flowing water; however, the source of that water is disputed. Possible water sources are hydrothermal systems driven by surficial lava flows and subsurface sills, impact events, and subsurface magmatic intrusions. Here we investigate systems driven by magmatic intrusions by first applying the boundary layer theory to obtain general results for heat and fluid fluxes and then use numerical modeling to explore other parameters including ice-melt contribution and brine formation. Previous models for magma intrusion driven hydrothermal systems on Mars (e.g. [1-5],) employed coarse spatial and temporal resolutions that made temperatures and velocities close to the chamber difficult to observe. Results from Gulick’s [3] model showed the importance of fluid behavior close to the chamber where a large change in temperature within < 100 m is evident. By employing the boundary layer theory, fluid behavior within close proximity to the chamber can be studied in detail. Additionally, our model improves upon previous models that considered intrusions and ice melting, but did not take hydrothermal circulation near the intrusion into account [4],[5]. Our analysis first developed steady state, twodimensional, thermal boundary layer models. By making the assumption that convection occurs within a thin layer, the boundary layer theory, as described by Cheng and Minkowycz [6], was used to derive a general solution. Then, mass and heat fluxes near the quasivertical boundaries of magma intrusions with heights ranging from 1 to 10 km were determined. Figure 1 describes the model set-up and parameters. The system’s non-linear governing equations of conservation of mass (eqn (1)), conservation of momentum (eqns (2)&(3)), and conservation of energy, (eqn (4)):