| Duricrust | |
|---|---|
 | |
| Key minerals | Soluble minerals |
| Climate | Arid |
| Primary | Various |
| Secondary | Various |
Duricrust is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters.
It is a general term (not to be confused with duripan) for a zone of chemical precipitation and hardening formed at or near the surface of sedimentary bodies through pedogenic or non-pedogenic processes. It is typically formed by the accumulation of soluble minerals deposited by mineral-bearing waters that move upward, downward, or laterally by capillary action, commonly assisted in arid settings by evaporation.[1][2] There are different types of duricrusts, each distinguished by a dominant mineralogy. For example, ferricrete (laterite) is dominated by sesquioxides of iron; alcrete (bauxite) is dominated by sesquioxides of aluminum; silcrete by silica; calcrete (caliche) by calcium carbonate, and gypcrete (gypcrust) by gypsum.[1]
Duricrust is often studied during missions to Mars because it may help prove the planet once had more water. Duricrust was found on Mars at the Viking 2 landing site, and a similar structure, nicknamed "Snow Queen", was found under the Phoenix landing site.[3] Phoenix's duricrust was later confirmed to be water-based.[4]
- ^ a b Dixon, J.C. and McLaren, S.J., 2009. Duricrusts. In A.J. Parsons and A.D. Abrahams, ed., pp. 123-151. Geomorphology of desert environments. Springer, Dordrecht. ISBN 978-1-4020-5718-2
- ^ Woolnough, W.G., 1930. The influence of climate and topography in the formation and distribution of products of weathering. Geological Magazine, 67(3), pp.123-132.
- ^ Rayl, A.J.S. (June 1, 2008). "Holy Cow, Snow Queen! Phoenix Landed on Ice, Team Thinks". The Planetary Society. Archived from the original on June 5, 2008. Retrieved November 12, 2008.
- ^ Nemiroff, R.; Bonnell, J., eds. (November 12, 2008). "Phoenix and the Holy Cow". Astronomy Picture of the Day. NASA. Retrieved November 12, 2008.