Liesegang rings (geology)

For other Liesegang rings, see Liesegang rings.
Typical Liesegang ring structures within cross-section

Liesegang rings (/ˈliːzəɡɑːŋ/) (also called Liesegangen rings or Liesegang bands) are colored bands of cement observed in sedimentary rocks that typically cut across bedding.[1][2] These secondary (diagenetic) sedimentary structures exhibit bands of (authigenic) minerals that are arranged in a regular repeating pattern.[3] Liesegang rings are distinguishable from other sedimentary structures by their concentric or ring-like appearance. The precise mechanism from which Liesegang rings form is not entirely known and is still under research,[4] but there is a precipitation process that is thought to be the catalyst for Liesegang ring formation, referred to as the Ostwald-Liesegang supersaturation-nucleation-depletion cycle.[5] Though Liesegang rings are considered a frequent occurrence in sedimentary rocks,[6] rings composed of iron oxide can also occur in permeable igneous and metamorphic rocks that have been chemically weathered.[7]

  1. ^ Jackson, Julia A., 1997. "Glossary of Geology." American Geological Institute, Alexandria, Virginia. 4th edition. P. 366
  2. ^ Stow, A.V., 2009, Sedimentary rocks in the field. A color guide (3rd ed.), Pp. 103, 107.
  3. ^ Middleton, Gerard V.; Church, Michael J.; Coniglio, Mario; Hardie, Lawrence A.; Longstaffe, Frederick J.; 2003. "Encyclopedia of Sediments and Sedimentary Rocks." Kluwer Academic Publishers, Dordrecht. Pp. 221, 224.
  4. ^ Krug, H.-J,. Brandtstadter, H., and Jacob, K.H., 1996. Morphological instabilities in pattern formation by precipitation and crystallization processes. Geologische Rundschau, 85: 19-28.
  5. ^ Decelles, P.G., and Gutschick, R.C., 1983. Mississippian wood-grained chert and its significance in the western interior United States. Journal of Sedimentary Petrology, 53: 1175-1191.
  6. ^ Merino, E., 1984. Survey of geochemical self-patterning phenomena. In Nicolis, G., and Baras, F. (eds.), Chemical Instabilities. Dordrecht: D. Reidel Publishing Company, pp. 305-328.
  7. ^ McBride, E. F. (2003), Pseudofaults resulting from compartmentalized Liesegang bands: update. Sedimentology, 50: 725–730. doi:10.1046/j.1365-3091.2003.00572.x