Melkart (crater)
Galileo image of Melkart and its surroundings | |
| Feature type | Impact crater |
|---|---|
| Location | Ganymede |
| Coordinates | 9°52′S 186°04′W / 9.86°S 186.07°W[1] |
| Diameter | 103 km[2]: 15 |
| Eponym | Melqart |
Melkart is an impact basin on Ganymede, the largest moon of Jupiter. 103 kilometres (64 mi) in size, its center hosts a distinct dome, surrounded by an irregularly-shaped depression and a rugged crater floor. The crater is named after Melqart, the tutelary god of the Phoenician city-state of Tyre. Its name was adopted by the International Astronomical Union (IAU) in 1979.
Geography and geology
Melkart is located on the western border of Marius Regio, a large region of dark terrain. It partially overlies a smalll northwest–southeast oriented sulcus that branches off from Tiamat Sulcus and connects to Sippar Sulcus.[3]: 5 Surrounding Melkart is a vast ejecta ray system.[2]: 15
Melkart is about 103 kilometres (64 mi) in diameter.[2]: 15 Its interior is dominated by a central dome 20–25 kilometres (12–16 mi) wide with a base–height elevation of 1.36 kilometres (0.85 mi), which is thought to have formed when warm icy material upwelled from the subsurface.[4]: 10 [3]: 2 The dome is slightly off-center to the northeast and is cut by several fractures and lineaments;[3]: 4, 6 its offset implies that the formative impactor struck the surface in a south-southwest to north-northeast direction.[2]: 15 An irregular smooth-floored depression surrounds the dome, and the crater floor has both knobbed and smooth terrain.[3]: 2 Its floor is divided into a darker and lighter section, which may correlate to the darker and lighter terrains of Marius Regio and the unnamed sulcus, respectively. A northwest-trending tectonic fault that cuts across the eastern portion of the crater delineates this divide. The fault is a right-lateral strike-slip fault, though it has a limited offset of less than 5 km (3.1 mi) at Melkart's crater rims. The fault has two main stepover zones at the central dome's borders, allowing for local contraction or extension.[3]: 4
Observations of Melkart's surface spectrum from Galileo's NIMS instrument indicate that its surface is composed of a mixture of water ice and hydrated minerals. The abundance of crystalline water ice varies between 50 and 75%; darker regions are associated with a lower abundance in water ice and higher abundance in relatively dark hydrated minerals.[5][3]: 12–13 The lighter and darker portions of its floor, though roughly coinciding with the border of Marius Regio, does not strictly correspond to any geological units within the crater itself. This may suggest that the border of Marius Regio was gradual at Melkart's site or that the darker material is only a shallow surface layer.[5][3]: 13
References
- ^ "Melkart". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program. (Center Latitude: –9.86°, Center Longitude: 186.07°; Planetocentric, +West)
- ^ a b c d Baby, Namitha Rose; Kenkmann, Thomas; Stephan, Katrin; Wagner, Roland; Hauber, Ernst (September 2024). "Ray and Halo Impact Craters on Ganymede: Fingerprint for Decoding Ganymede's Crustal Structure". Earth and Space Science. 11 (9). doi:10.1029/2024EA003541. e2024EA003541.
- ^ a b c d e f g Lucchetti, Alice; et al. (September 2023). "Geological, compositional and crystallinity analysis of the Melkart impact crater, Ganymede". Icarus. 401. Bibcode:2023Icar..40115613L. doi:10.1016/j.icarus.2023.115613. 115613.
- ^ White, Oliver L.; Moore, Jeffrey M.; Schenk, Paul M.; Korycansky, Donald G.; Dombard, Andrew J.; Caussi, Martina L.; Singer, Kelsi N. (January 2025). "Large impact features on Ganymede and Callisto as revealed by geological mapping and morphometry". Icarus. 426. arXiv:2403.13912. Bibcode:2025Icar..42616357W. doi:10.1016/j.icarus.2024.116357. 116357.
- ^ a b "NIMS Observes Melkart Crater on Ganymede". NASA/JPL. 26 March 1998. Archived from the original on 10 October 2025. Retrieved 11 December 2025.