Duricrust

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.

Duricrust
A duricrust inselberg near Dori, Burkina Faso
Key mineralsSoluble minerals
ClimateArid
PrimaryVarious
SecondaryVarious

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]

References
  1. 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
  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.
  3. 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.
  4. Nemiroff, R.; Bonnell, J., eds. (November 12, 2008). "Phoenix and the Holy Cow". Astronomy Picture of the Day. NASA. Retrieved November 12, 2008.

Further reading
  • DILL, H.G., WEBER, B. and BOTZ, R. (2013) Metalliferous duricrusts (“orecretes”) - markers of weathering: A mineralogical and climatic-geomorphological approach to supergene Pb-Zn-Cu-Sb-P mineralization on different parent materials.- Neues Jahrbuch für Mineralogie Abhandlungen, 190: 123-195


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