It's appears to be a graben. In tectonics, that is an area within an extensional terraine that drops down while the blocks on either side go up, in a relative sense.

If you look at the other high rez areas, they all seem to document the collapse of the ice sheet into the ocean. You can see all kinds of extensional fracturing along the coast.
Note that the low rez areas show that there is a dark feature running into this oval. Is that the shadow of a scarp of is it a stretch of open water between separating ice sheets?

Also note that there is new snow coving the feature, it would probably look very different at the end of the Antarctic summer.

However, it also looks like a pull-apart basin. This would occur if the ice is moving laterally, and not just pulling apart, and the bends in the crack open to create basins. The way to visualize this is to hold your hands together, palm to palm. Slide them slowly back and forth and you'll see the as you do so, the irregularities in the sliding surface produces voids. Those are pull-apart basins. In other photos I can see what are called en-echalon fractures, where there is not one crack, but a whlole series of cracks that side-step at a small angle to the major crack direction. This may be why the major axis of the ellipse is at an acute angle to the major cracks that the oval feature sits on. This would suggest the ice is not just extending into the ocean, but it is also moving along the coast.

It's hard to decide between these two models, but it seems to me this is a structural effect of the moving ice at the edge of the ice sheet obscured by this winter's snow cover.