Bear with me here and, please, no biteing. ;)

Much of the reasoning here is highly descriptive so I'm not going to feel too bad if this doesn't fly far.

Here on Earth, snow avalanches build up enough heat through friction to partially melt while flowing, but, freeze solid once the flow ceases.
The resulting material is porous water ice which is as hard as concrete. This is why you don't want to be buried in one. It's not just fluffy powder....

Anyhoo, it's reasonable to assume that, in a dusty avalanche, there would be a certain degree of heating. Unkown #1, how much?

Now, assume that the dusty sediment has a coating of carbonates like has been observed elsewhere on the planet. Unknown #2, could it?
Unknown #2.5, can a coating source enough CO2 to make a difference?

Also, I couldn't find this in the CRC or via a quick Google, but, do carbonates decompose (releasing CO2) at a lower temperature under Martian ambient pressure? Unknown #3, is it required?

Obviously, if there is CO2 frost in the flow, this simplifys
the source process.

Any thoughts, comments, teeth marks...?