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Duricrust

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

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]

References

  1. ^ 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
  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


Quelle: https://en.wikipedia.org/wiki/Duricrust