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Cool image time! When I first looked at the high resolution Mars Reconnaissance Orbiter (MRO) image on the right, my immediate reaction was, “What the heck is that?” The image to the right is cropped and reduced, but if you click on it you can see the full image at high resolution.
The fractured terrain appears to be all within a collapse. To my eye it appears that while the overall surface has sunk, the fractures indicate an area where there has been an eruption upward, which after the eruption collapsed again, so that the fractured area remains at the apparent bottom of the collapse sink. I was immediately reminded of Upheaval Dome in Yellowstone National Park, which some geologists believe was formed by a “salt bubble” rising upward to create a salt dome.
A thick layer of salt, formed by the evaporation of ancient landlocked seas, underlies much of southeastern Utah and Canyonlands National Park. When under pressure from thousands of feet of overlying rock, the salt can flow plastically, like ice moving at the bottom of a glacier. In addition, salt is less dense than sandstone. As a result, over millions of years salt can flow up through rock layers as a “salt bubble”, rising to the surface and creating salt domes that deform the surrounding rock.
The process and materials involved were certainly different on Mars. Nonetheless, it does appear we are looking at an eruptive feature unrelated to molten lava. The context image to the right, showing this feature’s location in Mars’ vast northern lowlands, also shows that it has occurred on terrain that has bulged upwards relative to the surrounding lowlands. Nearby MRO images also show similar bulge/collapse features.
To decipher the geological mystery here, we would also need to know when this happened and whether there ever was a liquid ocean residing on top of it, before, during, or after the eruption. We also do not know well the make-up of the underground materials, including whether any frozen water and salt is present.
To be honest, we really don’t know much. I am sure a planetary scientist studying this feature could fill us in on some of these details, such as information provided by the colors in the color image. Even so, I am sure any good scientist would also admit to unknowns.
To get some real answers, we need to be there. It is as simple as that.