Lamina (geology)

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deformed lamination structure of sintered lime
biogenic lamination of stromatolites

Lamina (from the Latin lamina = plate, disc; plural : laminae ) is a geological feature of layered sedimentary structures. The term describes the smallest unit - a light or dark individual layer - of a laminite . A laminite is a sediment deposited in thin layers , the name of which refers to the defining structural feature. An example of this deposit form are varves .

Laminae are defined as individual layers that are less than 1 cm thick, but are usually significantly thinner (thicknesses of less than 0.1 mm to 1 mm are common phenomena). Layers over 1 cm are called a bench . The types of lamination according to their formation ( clastic , organogenic and evaporitic ) are variants of this structure. What they have in common is the fine grain of the sediment.

Laminites arise in stagnant or slowly flowing waters - the flow in parallel streams (equidistant paths) is called "laminar flow" - but can also form in certain phases with lava flows and mud flows.

When a rock sequence is built up in this way, it is said to be "laminated". "Lamination" or "lamination" are names for the process that leads to the formation of a laminite. Under Warve you will find further explanations on the method of formation.

  • Lamination structure in different rocks

  • Lamination structure (clastic) in a sandstone

  • Lamination structure (evaporitic) in a travertine

  • Type deformed lamination in an itabirit

literature

Individual evidence

  1. ↑ Murawski, H., Meyer, W. (2004): Geological Dictionary. Spektrum Akademischer Verlag, 11th edition, 262 pp. ISBN 3-8274-1445-8