https://www.cnet.com/news/game-of-thrones-season-8-fever-reaches-mars/

The dark streaks are actually impact-induced dust avalanches, which sounds like something you might encounter in sandy Dorne. 

"In this scene we see what appears to be a new impact cluster and, extending downhill from the craters, new dark slope streaks," the HiRise team reported. The avalanches exposed the darker ground beneath.