This Magellan image centered at 25o South, 82.5o longitude shows a corona located about a thousand kilometers south of Aphrodite Terra. This unnamed corona is 375 km in diameter; it flanks a north-south trending fracture zone which meets a smaller corona in the southeast corner of the image. Coronae are thought to form as a result of heat flow from the interior of the planet melting the crust. The molten material rises toward the surface, causing it to dome. As it subsequently cools off, the dome collapses. The annular ring of fractures and graben, visible in this image, along with the volcanic domes in the center are characteristic features of coronae. Other features associated with the large corona are also noteworthy. The bright rim along the northern edge of the corona may represent blocky debris which has fallen from its flank. The pancake dome on the western edge of the corona is a viscous extrusion; it is thought to be younger than the adjacent graben, since it is superposed on top of them. The coronae are found amidst lava plains. Individual flow complexes are distinguished from each other by variations in radar brightness. This suggests subsequent events which resulted in lavas of different textures (bright grays are blockier, while darker ones are smoother). The light gray blotch in the radar-dark circumferential valley on the northwestern edge of the large corona is a section of the plains, which, because of its relative height, did not get covered by the non-viscous flow. This flow was discharged from the corona through fissures.
