Ann: Drilling Update, page-118

In case anyone was still a bit confused about the horst-graben geology, i've drawn a little sketch showing my interpretation, which I admit could still be inaccurate in some places (apologies for it being messy - handwriting is not my strong suit).

Basically, the basement and Breccia (which is the medium containing the brine) shift downwards at some point as you go south along Candelas. The sands and clays would contain groundwater. The breccia can increase in elevation and still host brine because it is less permeable than the sands/clays - water would be flowing extremely slowly from the sands and clays into the brecca, and the brine in the breccia flowing slowly towards (i guess) the north.


Of course I'm open to being proven wrong, and reality to be something completely different (e.g. discontinuous), this is just what makes logical sense to me.