... darn, structurally speaking. Pretty much like the chlorides. Load anything on them and they move like silly putty. Deload them, and they flow towards the lower over-burden pressure area. What would an impact do? Upheaval Dome might be a terrestrial analog.

On hydrothermal springs. Accepting that there's ample groundwater, what is the heat source? The heat of impact? How long does that last? The temperature of the spring is the thing. So's the salinity of the water. Low temperature brines are quite capable of dissolving metals, etc. Especially if they are acidic. They'll make simple travertine deposits but are too low in temperature to create "black smokers". We need a fairly epithermal igneous intrusion with a slow cooling curve to establish a robust hydrothermal cell to create a black smoker. I've never looked into the thermal decay of meteorite impact. But I don't think it is anything compared to a nice, slowly cooling intrusion. (or thick extrusive flow)

It's late...just rambling....