In zone 1, there is a recent impact which entered from the left. It created two concentric circles in the land ice from shock waves.
The impact is young as tholin is still exposed. The methane snow has yet to cover the scene.
The outer edge of the subsurface damage is smooth looking more like a fluid while the inner edge is jagged and lined with a few mud daubers.
This impact scenario repeats in zone 3.
The more I look at it the more it looks like the shock wave damage with the smooth looking melt extends much further than I pointed out in the images above.
This demonstrates two things, how far shock wave damage can travel relative to the size of the impacting object and how difficult it can be to define the borders of the damage.
There are ring patterns within this area helping to outline the fluid which created a basin looking depression.
This looks similar to the western basin called Peri Planitia.