Galileo Regio is a large, dark surface feature on Jupiter's moon Ganymede. It is a region of ancient dark material that has been broken apart by tectonism and is now surrounded by younger, brighter material (such as that of

Uruk Sulcus Uruk Sulcus is a bright region of grooved terrain adjacent to Galileo Regio on Jupiter's moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to ...

) that has been upwelling from Ganymede's interior. It is thought to be some 4 billion years old and is heavily cratered and palimpsested, but also has a unique distribution of furrows and smooth terrain that has been the subject of conflicting speculation regarding cause or origin. The distribution of smooth terrain on Galileo Regio suggests that the ancient crust of Ganymede was relatively thin in the equatorial region and thickened poleward in this area. The age relationships, morphology, and geometry of the furrow systems do not favor an origin by impact or tidal stressing. A possible, but speculative, origin is crustal uplift caused by a plume-like convection cell in a fluid mantle underlying a thin crust. Stratigraphic and morphologic relationships among furrows and crater palimpsests suggest that palimpsest morphology is largely the result of impact into a rheologically weak crust rather than viscous relaxation. The regio is bounded on the southwest by Uruk Sulcus, which lies between it and

Marius Regio Marius may refer to: People *Gaius Marius (157 BC-86 BC), Roman statesman, seven times consul. Arts and entertainment * ''Marius'' (play), a 1929 play by Marcel Pagnol * "Marius" (short story), a 1957 story by Poul Anderson * ''Marius'' (193 ...

. Within Galileo Regio itself lies the

palimpsest In textual studies, a palimpsest () is a manuscript page, either from a scroll or a book, from which the text has been scraped or washed off so that the page can be reused for another document. Parchment was made of lamb, calf, or kid skin an ...

Memphis Facula Memphis Facula is a palimpsest, or "ghost crater", on Ganymede, the largest of the Jovian satellites. About 360 km across, it is situated in the southwestern part of Galileo Regio, a huge almost circular dark region in Ganymede's norther ...

, a relic of an

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...

that has been flattened in a manner characteristic of some of the Solar System bodies with icy crusts.

References

# Harland, D. M.; Jupiter Odyssey, Springer Praxis (2000), p. 141 # Casacchia, R., and R. G. Strom (1984), Geologic evolution of Galileo Regio, Ganymede, J. Geophys. Res., 89(S02), B419–B428, doi:10.1029/JB089iS02p0B419. {{Ganymede Surface features of Ganymede (moon) Ganymede (moon)