Cementation is the process of deposition of dissolved mineral components in the interstices of sediments. It is the sticking together of sediment to form a new rock and is an important factor in the consolidation of coarse-grained clastic sedimentary rocks such as sandstones, conglomerates, or breccias during diagenesis or lithification. Cementing materials may include carbonates, quartz, iron oxides, or clay minerals.
Cementation is also continually going on in the groundwater zone, so much so that the term "zone of cementation" is sometimes used interchangeably. Cementation occurs in fissures or other openings of existing rocks and is a dynamic process more or less in equilibrium with a dissolution or dissolving process.
Types of carbonate cement
Beachrock is a type of carbonate beach sand that has been cemented together. Beachrock may contain meniscus cements or pendant cements. As the water between the narrow spaces of grains drains from the beachrock, a small portion of it is held back by capillary forces, where meniscus cement will form. Pendant cements form on the bottom of grains where water droplets are held.
Hardgrounds are hard crusts of carbonate material that form on the bottom of the ocean floor, below the tide. Isopachous (which means equal thickness) cement forms in subaqueous conditions where the grains are completely surrounded by water (Boggs, 2006).
References
- Boggs, Sam Jr., 2006, Principles of Sedimentology and Stratigraphy, 4th ed., New Jersey, Pearson Education Inc.
See also
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