Geology and Mapping of Venus

Maat Mons is the tallest volcano on Venus and the location of the multiplayer map Shores of Time. Due to the proximity to the flanks of Maat, we would expect many rocks to be volcanic in this area. Some hydrothermal features can be seen in the surrounding areas, venting gasses and depositing fine-grained white deposits (sulfates?) reminiscent of travertine deposits on Earth. The vesicular patterns in the basaltic rocks that form the walls and corridors of this area are curious in nature... could these actually be carbonates? Given the proximity to the Venusian ocean, this might make some sense, however, it implies a level of tectonic activity which we have not witnessed on Venus.