Sedimentary rocks are formed thanks to the precipitation and accumulation of minerals of a solution (from liquids) or, thanks to the compaction of remains of living beings (both animals and vegetables) that are compacted until consolidating in hard rocks.
If you want to know more about sedimentary rocks, their types, classification, examples and how it is formedN, keep reading this ecology article dedicated to this large group of rocks that covers 75% of the surface of our planet.
Sedimentary rock formation
The sedimentary rocks They are a type of rocks that are always formed on the earth’s surface from pre -existing rocks that pass through the call sedimentary processwhich ends up turning them into sedimentary rocks as such. This sedimentation process consists of different large general phases.
- Erosion: Either biological, chemical or mechanical type, this phase of the sedimentary process is characterized by the destruction of the pre -existing solid rock, decomposing it into smaller fragments. Destroying agents can be wind, water or ice.
- Transport: In this phase, water in its different states or the wind transports the fragments product of erosion.
- Deposit: The sediments transported by water, wind or ice are accumulated in depressed areas prone to it, such as deltas, lakes, graves or basins.
- Compaction and Diagenesis: Physical and chemical processes compact accumulated sediments, so that they end up transforming them into sedimentary rocks.
It is due to the nature of this formation process that sedimentary rocks tend to be formed in layers or strata, which allow differentiating by studying the different phenomena that occurred during certain periods of time.
Types and classification of sedimentary rocks
There are two great forms of classify sedimentary rocks: for its training and for its composition. On the one hand, the different Types of sedimentary rocks according to their formation They are classified as:
- Detritical or classic sedimentary rocks: These are sedimentary rocks that have been formed due to accumulation during large periods of sediment time from the erosion of large rocks, slopes or mountains, and deposited by simple effect of gravity. Depending on the size of the compose them, they are classified in turn into conglomerates, sandstones and clay rocks.
- ORGANOGEN ROCKS: These rocks are formed with living beings. The most common is to find them formed by the biomineralization of skeletons, but there are also formed from cell matters, called organic rocks.
- Chemical sedimentary rocks: When chemical processes such as evaporation of seawater are given, there is a salt residue and other minerals. Chemical rocks are formed by the deposition and accumulation of chemical processes such as this.
- Margas: This is a type of mixed sedimentary rock that is formed by the accumulation of detritic rocks with chemical rocks. Because of this, some experts prefer not to consider them a type of sedimentary rock itself.
On the other hand, the Types of sedimentary rocks according to their composition They are classified as:
- TerRIGENS: They are formed by terrigo sediments, mainly granite or silíceas organic particles, and usually with high quantity amounts.
- Carbonatics Mainly composed of carbonate minerals, usually calcium. They constitute a third of the total sedimentary rocks.
- Silíceas: These rocks are formed by organic silicon particles or granite weathering.
- Organic: Sedimentary rocks of this type have their origin in organic matters of living beings, either of their skeletons or cell matters.
- Ferro-Alumine: When a Ferro-Aluminíca ore undergoes a weathering process due to a volcanic eruption or a similar process, this type of sedimentary rocks is created, very rich in metals.
- Phosphatic: These rocks, more difficult to find, are created from the guano lithification process, that is, bird excrements, although it is not their only form of formation.
Examples of sedimentary rocks
There are a lot of sedimentary rocks that we see in our day to day. Some Examples of sedimentary rocks are the following:
- Coal: You cannot talk about organic sedimentary rocks without mentioning mineral coal, and even oil. These valuable substances have currently been formed from the lithification of organic remains, and are therefore sedimentary rocks.
- Evaporitas: GEMA plaster and salt are some of the best known evaporites, formed from the evaporation of seawater and crystallization of their remains.
- Limestone: The limestone rock, used both under construction and in gardening, is a carbonatic sedimentary rock that is formed in shallow sea waters of tropical areas.
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