Airey, Martin and Tyson, Shelly and Lane, Stephen and Gilbert, Jennifer and Wilson, Lionel (2012) Magma-cryosphere interactions on Mars:VMSG 2012, Durham UK. In: Volcanic and Magmatic Studies Group 2012, 2012-01-042012-01-06.
Full text not available from this repository.Abstract
The Martian cryosphere, a mixture of rock and ice of various compositions and structures, is thought to dominate the near surface crustal geology of the planet. During the long volcanic history of Mars, magma and cryosphere must have frequently come into contact with one another. It is important that the thermodynamic and structural response of cryosphere to magmatic intrusions is better understood in order to better characterise the effects of such processes. The cryosphere formed due to the atmospheric pressure and temperature conditions on Mars along with a waning global heat flux. Atmospheric H2O was progressively cold-trapped at the poles, some of which was incorporated into a global aquifer and subsequently built up in the uppermost regions of Mars’ crust as the cryosphere. Geomorphological evidence for magmacryosphere interactions includes outflow channels, phreato-magmatically produced ridges, lahars, pit craters and graben. We have carried out experiments to simulate magmatic intrusion into cryosphere. Experiments were run with a heater embedded within a cryosphere analogue, subjected to various water saturation and temperature regimes and the results were processed graphically. We found that the thermal gradient and temperature of the cryosphere analogue were dependent on the water content of the experimental material and the phase of the water, with much higher temperature, steeper gradients through the gaseous medium than through the liquid. Latent heat was found to be important in the behaviour of the thermal response of the experimental material. Pressure changes in response to phase transitions caused low temperature vaporisation in sealed systems. Segregation of H2O phases occurred in the unsaturated system, which promoted greater energy transfer to the top of the melt region. It is postulated that many features seen on Mars may have formed as a result of these types of interactions.