Maturity (sedimentology)

In sedimentology, maturity describes the composition of grains in sandstones occurring from various amounts of sediment transportation. It occurs when the grains in a sediment become well-sorted and well-rounded due to weathering of the grains. There are two components to maturity: texture (how rounded and sorted) and composition (how much the composition trends toward stable minerals and components). Mature sediment is more uniform in appearance, for the edges of the grains in the sediment are smoother and are of a similar size. Conversely, an immature sediment contains angular grains, diverse grain sizes, and is compositionally diverse.^[1]

As the sediment is transported, the unstable minerals react with their surroundings or weather away to leave more stable minerals, such as quartz. Mature sediments, which contain stable minerals, generally have a smaller variety of minerals than immature sediments, which can contain both stable and unstable minerals. One measure of this maturity is the ZTR index.

A rock sample from a river downstream is likely to be more mature than one found upstream, since the original sediment has been subject to more weathering conditions as it travels downstream.

See also

• Rounding
• Sorting
• Sediment transport

References

1. ^ Boggs Jr., S. (2006). Sedimentology and Stratigraphy. Pearson Education. ISBN 0-13-154728-3.