How could this "aztec temple" mountain (or volcano) have been formed on Antarctica?
Remember that Antarctica is covered in a sheet of ice. Strip away the ice and you get something like this:



(Source:Wikimedia Commons)

This is the Matterhorn in the Alps on the Swiss-Italian border. The word horn is used in glacial geomorphology to refer to a mountain peak that has been ground by glaciers on many sides to create a "pyramidal peak" with sheer, faceted sides.

During the Pleistocene ice ages, the Alps were covered in an ice sheet much like Antarctica is today, and undoubtedly at some point the tip of the Matterhorn poked through the top of the ice, looking very similar to the mountain in your picture.