When we talk about the rock cycle or sedimentary cycles, we are referring to the series of stages through which certain mineral elements and rocks evolve during their time in the Earth's crust. All phases of the cycle involve a sequence of transformations that change the rock's formation and composition. Ultimately, various transformations occur in a cyclical time series that repeats itself over long periods.
In this article we are going to tell you everything you need to know about the rock cycle and its importance.
What is the rock cycle
We must keep in mind that this is a biogeochemical cycle in which the storage of a specific element occurs in the Earth's crust. All the mineral elements present are part of the rock cycle, also known as the sedimentary cycle. For example, we have some mineral elements such as sulfur, potassium, phosphorus, calcium, and other heavy metals.
The rock cycle begins with an exposure of rocks to these elements from deep within the crust. They can also be found in areas close to the surface. After they are exposed, they are subjected to weathering processes, for which they also suffer erosion by external agents. Among these external agents we have the atmospheric, hydrological and biological factors.
All the material that erodes over time is transported by water, gravity, or wind. Once transported, the material settles in a specific location to undergo sedimentation. Sedimentation is simply the process of depositing mineral material onto the substrate. Layers of sediment accumulate over thousands of years, so we must remember that this is measured on a geological timescale . Over these millions of years, the sediment undergoes complex processes of compaction and cementation.
This is how sediments lithify, transforming into solid rock. This process occurs at great depths. Furthermore, the rock cycle includes intermediate phases driven by biological processes. These biological phases include solubilization and absorption by living organisms. Depending on the type of mineral, its composition, and the environmental conditions, minerals can be absorbed by plants, bacteria, or animals and enter the food web . Once absorbed, the minerals are excreted or released through the death of the organism. This completes the cycle.
Key features
We will analyze the main characteristics of the rock cycle. We know that it is one of the three types of biogeochemical cycles, and its main characteristic is the isolation matrix within the lithosphere. These cycles have their own discipline of study called sedimentology. Sedimentology is the science that studies the rock cycle and its importance in the geology of the Earth.
The length of the cycle is characterized by the time it takes to complete different stages. This time is often too long to measure on a human scale. It must be measured in millions of years because minerals remain embedded in rocks for long periods of time. These rocks are usually located deep within the Earth's crust. The pressure exerted by gravity and other materials is one of the main drivers that triggers the beginning of the rock cycle.
Stages of the rock cycle
Let's look at the different stages of the rock cycle. It's important to remember that this isn't a cyclone whose stages always follow a written sequence. Since they're normally influenced by different variables and factors, the phases can occur or alternate several times during the process.
Exposure phase
This is the phase where rocks formed at certain depths within the Earth's crust are subjected to diastrophic processes. These processes manifest as various fractures, folds, and uplifts of the terrain. These ground movements are primarily due to plate tectonics and plate movement. As a result, the rocks are exposed to the action of various environmental factors, including edaphic, atmospheric, hydrological, and biological factors.
Diastrophism is simply the result of the movements between convection currents in the Earth's mantle. These movements are also generated by volcanic activity, which exposes rocks more intensely.
Weathering phase
During the weathering phase, exposed rocks undergo decomposition into smaller fragments, which is physical weathering, or changes in their mineralogical composition, which is chemical weathering. This is a key factor in soil formation and can be not only physical or chemical, but also biological.
Erosion phase
In this phase, we see the direct action of wind and rain on the rock. These are products of weathering, which also includes the soil formed. The erosion phase also involves the transport of previously eroded material. It is attacked by erosive agents such as wind and rain.
Transport phase
The mineral particles are transported by these agents, be it water, wind or gravity itself. They are transported long distances, although depending on the size they have a defined load capacity.
Sedimentation and accumulation phase
It consists of the deposition of transported material due to a decrease in the speed of the transport medium and the effect of gravity. It can be fluvial, tidal, or seismic sedimentation.
Rock cycle: solubilization, absorption and biological release
Once all the rock material has weathered, the released minerals can also dissolve. These minerals can also be absorbed by living organisms. Plants are consumed by herbivores, and these are consumed by carnivores. Ultimately, it is the decomposers that pass the minerals into the food web.
The final stage of the rock cycle is lithification. This is divided into compaction and cementation. Lithification is simply the formation of a new rock. It occurs when minerals are deposited, forming successive layers that accumulate and exert enormous pressure. During compaction, the pressure exerted by the layer of sediment increases in successive phases.
Finally, during the cementation phase, cementing substances are deposited between particles. These cementing particles are typically calcite, silica, oxides, and others, which are responsible for crystallizing and cementing the material. Thus, solid rock is generated.
I hope that with this information you can learn more about the rock cycle.