Over the years, many geological and natural events have been changing the terrestrial formation until today. One of these processes is orogeny, the natural phenomenon that models our mountains or reliefs. Let’s see more about this interesting topic!
What is meant by orogeny?
Orogeny refers to a series of processes that have been occurring for a long time in the earth’s crust, where new structures have been formed or rejuvenating some that were already part of the environment.
In this way it can be said that orogenesis is a process that has been taking place for millions of years. Currently these events continue to occur, giving origin to new mountains, valleys or plateauswhich change through the process of orogenesis.
In geology, orogeny is defined as a type of process that results in the formation of mountains and mountain ranges in a slow and long period. This occurs horizontally since orogeny implies that a elongated area of the Earth’s crust widens or narrows due to a force in the lithosphere.
The orogeny is given by the shifting tectonic plates of the earth’s crust, which allows the natural formation of mountains. In other words, it is the way in which changes are expressed in the terrain and in the aspect of the lithosphere due to the action of earthquakes.
How does orogeny occur?
The process for orogenesis to happen can be very slow, it can even reach take thousands or millions of years. The same occurs due to the deterioration of the mountains, which leads to the loss of peaks caused by continuous erosion, which can be due to:
- The rain.
- different types of weathering.
- Some geological agents.
- Changes in the environment.
In this way, the Earth will be rejuvenated on its surface by means of folding and movement of plates tectonics, leading to the origin of new mountains or mountain ranges. Some processes that occur during their formation are defined below:
- He folding, which refers to the collision between different elements with soft characteristics. At the time of these foldings, the earth’s crust begins to change and, from this, the formation of small hills originates.
- He faultingis a process where all those materials with greater resistance and great hardness, including the folds, will end up breaking.
- He overridingoccurs at the moment when the matter begins to move from its point of origin to a different one.
Geology indicates that during the evolution in the orogeny there were movements of the tectonic plates that came to produce volcanic eruptions, being an example of this the Andean type orogeny. However, if the process that forms is of the mechanical or collision type, it is very difficult for volcanoes to form. On the other hand, if the orogenesis is of thermal typeyes volcanic formations occur.
In the processes that occur by collision in the lithosphere, spaces full of folds and areas of thickening are formed. It should be noted that this occurs when a continental plate ends up being located on top of another, which can be observe in the formation of the Alps.
Thanks to all these processes, elongated structures are created that have slight bulges in the form of arches, which are called “orogenic belts”, because of the shape they have. It is possible to identify them due to their stretched slice shapes and the parallel position in which the rocks are found.
Through all the widening that occurs, the belts remain linked to the different spaces where tectonic plates subduct, that is, when one plate is positioned on another. All these processes end up giving rise to the formations that we know today as volcanoes.
What is the function of orogenesis?
The process that leads to the development of orogeny works to help perceive and recognize what shape the mountains that will be created will have. They start with a folding phase.where little by little the soft elements of the surface collide with each other.
Following this occurs the failurewhich is the moment in which the soft objects collide with the hard elements, where they end up breaking the folds and giving rise to the last process that is the ridingwhich consists of one plate moving above or below the other.
What are the types of orogeny?
Various processes occur in orogeny, and each one leads to a different type of result. For this reason, it is important to highlight the different types of orogenesis that may exist:
symmetric orogeny, which occurs when two continental plates retract into an existing depression in the Earth’s crust. Examples of this orogeny are observed in the following natural structures, such as:
- The Pyrenees.
- The Alps.
- the himalayas
asymmetric orogeny, which takes place due to a continental plate colliding with an oceanic one. The result is the folding of sediments and their subsequent accumulation in subduction areas. For this reason, the oceanic sheet subducts and, on the other hand, the continental will prevail. We have the following examples of this type of orogeny:
- The Rocky Mountains.
- The Andes
The Andean orogeny is responsible for the formation of the Andes mountain range, which originated during the Jurassic period and continues to change to this day. It must be taken into account that since the separation of the Rodinia supercontinent occurred in the Neoproterozoic period, this has resulted in South America being subject to various types of orogeny.
In this period of the Paleozoic different orogenies took place, among which we find the following:
- The Pampas orogeny.
- The famatinian orogeny.
- The Gondwanan orogeny.
These would be the orogeny processes that gave rise to the Andean mountain range. Thus, we have that the first stages occurred during the Jurassic and Cretaceous periods, where an extensive tectonic plate was found.
The insular or island arc orogeny is located in the limits in which the terrestrial lithosphere is subducted under the oceanic lithosphere. Some islands are included in this type of grouping, such as:
- The Mariana Islands.
- the philippines
These islands represent examples of orogens found partially submerged. Due to the existence of a weak coupling of both plates, the subduction of oceanic sediments is allowed. Therefore, the consequence is that they do not stack, hindering the subduction process.
It should be noted that between the arc of islands and it there is a small zone or oceanic basin, which is called a marginal basin. In the same way, the trajectory from the ocean to the continent distinguishes different areas, among which we have:
- deep pit.
- Little or no accretionary prism developed.
- island arc.
- fringe basin.
The Alpine orogeny gave rise to the formation of different mountains, which took place in the Cenozoic period. This occurs when Africa, India and the small Cimmerian plate collided with Eurasia.
From this event the main orogenic chains of southern Europe and Asia were formed, beginning in the Atlantic Ocean and ending in the islands of Java and Sumatra. Among these we find the following islands and locations:
- Betic Cordilleras.
- Cantabrian Mountains.
- The Pyrenees.
- Dinaric Alps.
- balkan mountains.
- Carpathian Mountains.
- Elburz Mountains.
- Hindu Kush.
- Taurus Mountains.
The movements in the tectonic plates that gave rise to the Alpine orogeny occurred in the lower cretaceous, although most of these processes took place in the Oligocene and Miocene period. In this way, the central phases in which the Alps, Carpathians and the Atlas were formed took place between 37 and 24 million years ago.
What are the stages of orogenesis?
The orogeny has developed in different stages or cycles throughout history and evolution of mountain systems. In this way, these will include from the materials that will form it to the erosive action that will be carried out, including the stages of deformation and orogeny as such. Among the periods of the orogenic cycle we find the following:
- Sedimentation period or lithogenesis: In this stage, the materials that will make up the future mountainous system originate. Sedimentation processes occur in long, narrow ocean basins, which are called geosynclines.
- Period of orogenesis or folding: This cycle represents the grouping of the development phases of a mountain belt, including within these the preparation or uplift, uplift and erosion.
What is the importance of orogeny?
Orogeny plays a very important role in the structure of the nature of our environment. It also plays a fundamental role in the rejuvenation and training of new mountains.
Some of the changes climatic and ecological that have been occurring recently on the planet are related to orogeny, and due to this, also the movement of translation and subsequent readjustment of the different continental masses that exist on the entire terrestrial surface.
When the lifting of a large number of relief portions, different characteristics will be altered in the environment. Among which we got the following:
- circulation in the atmosphere.
- The increased air currents.
- Earth temperature change.
- The proper distribution of moisture.
- Movements on the ocean floors.
In the same way, there is the possibility that there are certain points that accelerate these lifting processes, which increase erosion and cause weathering. It should be noted that these processes result in a decrease in the emission of atmospheric carbon dioxide, and occur due to an increase in carbonation, which is found in the elements that make up the air. In addition, there are also silicates which are subjected to different erosions
Due to these events, the carbon dioxide retention, reducing its concentration in the atmosphere. In this way, a usual cooling is generated in the climate of the entire planet Earth.
The orogeny becomes a process of great importance for the relief transformation of the earth’s crust, helping in the renewal of the mountainous belts, considering the earth’s crust as a living entity. Therefore, it is constantly changing over time, coming to rearrange and form new valleys, plateaus, volcanoes and mountains.