25th September 2013 Sol 404

We have now left Waypoint Point 1 and started out for Waypoint 2, at about 1 km distance. 

At Leicester University and the Open University (Dr Susanne Schwenzer) we are busy preparing a paper which uses a variety of ChemCam, CheMin, APXS data to work out the processes and conditions (T, fluid composition, pH etc.) that the alteration minerals at Yellowknife Bay experienced.  Its a big challenge but fascinating.  By knowing the thermodynamic properties of the minerals we can backtrack though modelling and terrestrial analogues to what went on with water in Gale Crater about 4 Gyr.  The calculated fluids can then be used to understand other secondary assemblages that we encounter on the way to, and at, Mt. Sharp.

The image shows an example of  the minerals that would precipitate from a likely alteration fluid at a variety of water to rock ratios (W/R).  They are similar to the minerals identified in the Sheepbed mudstone of Yellowknife Bay.