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[edit] Secondary crater
Secondary craters are impact craters formed by the ejecta that was thrown out of a larger crater. They sometimes form radial crater chains.
[edit] External links
[edit] Zunil crater
| Zunil | |
| Region | Athabasca Valles |
|---|---|
| Coordinates | 7.8° N, 193.9° W |
| Diameter | 10.4 km |
| Discoverer | McEwen et al[1] |
| Eponym | Zunil |
Zunil is a crater in Athabasca Valles, Mars with a diameter of 10.4 km. It is named after the Guatemalan town of the same name. The crater was discovered by McEwan et al after following bright streaks of material along the crater's radial lines back to the crater. [1]
[edit] Formation
The impact created a ray system that extends up to 1600 km from the crater and produced 108 secondary craters with diameters ranging from 10 m to 100 m. Very few of these secondary craters lie within 80 km of Zunil. If similar impacts also produced comparable amounts of secondaries, this calls into question the accuracy of crater counting as a dating technique for Martian surface features. [2][3]
A simulation of the Zunil impact ejected on the order of a billion rock fragments greater than 10 meters in diameter. The simulation also produced secondary craters 10m in size up to 3500 km away from the primary impact. It is possible that some of these fragments made it to Earth to become Martian meteorites. [3]
[edit] References
- ^ a b McEwan et al (2003). "Discovery of a large rayed crater on Mars: Implications for recent volcanic and fluvial activity and the origin of Martian meteorites" in Lunar and Planetary Science Conference..
- ^ Kerr, R (2006). "Who can Read the Martian Clock?". Science 312: 1132 - 1133. doi:.
- ^ a b McEwan, A.S. et al (2005). "The rayed crater Zunil and interpretations of small impact craters on Mars". Icarus 176: 351 - 381.
- McEwan et al (2002). "Athabasca Valles Region: New Insights from Themis" in American Geophysical Union Fall Meeting..
[edit] External links
[edit] Paper dump
- (bonnevillecrater.pdf) Squyres, et al. "Surficial Deposits at Gusev Crater Along Spirit Rover Traverses". Science 305 (5685): 807 - 810. doi:.
- (cratercounter.pdf) Kerr, R (2006). "Who can Read the Martian Clock?". Science 312: 1132 - 1133. doi:.
- (homeplate.pdf) Squyres, et al. "Detection of Silica-Rich Deposits on Mars". Science 320: 1063–1067. doi:.
- (impactgardening1.pdf) Hartmann et al (2001). "Martian Cratering 7: The role of Impact Gardening". Icarus 149: 37-51. doi:.
- (impactgardening2.pdf) Housen et al (1979). "Asteriodal Regoliths". Icarus 39: 317-351. doi:.
- (jezerocrater.pdf) Ehlmann et al (2008). "Clay minerals in delta deposits and organic preservation potential on Mars". Nature Geoscience 1: 355 - 358. doi:.
- (minites.pdf) Silverman et al (2005). "Miniature thermal emission spectrometer for the Mars Exploration Rover". Acta Astronautica 59 (8-11): 990-999. doi:.
- (secondarycraterdating.pdf) McEwen, A; Bierhaus, E (2006). "The importance of secondary cratering to age constraints on planetary surfaces". Annual Review of Earth and Planetary Sciences 34: 535 - 567. doi:.
- (tychosecondaries.pdf) Dundas, M.; McEwen, A. (2007). "Rays and secondary craters of Tycho". Icarus 186: 31 - 40. doi:.
- (zunilcrater.pdf) McEwan, A.S. et al (2005). "The rayed crater Zunil and interpretations of small impact craters on Mars". Icarus 176: 351 - 381.
- (zunilcrater2.pdf) McEwan et al (2003). "Discovery of a large rayed crater on Mars: Implications for recent volcanic and fluvial activity and the origin of Martian meteorites" in Lunar and Planetary Science Conference..
