Today we're going to talk about one of the branches of geology that focuses on the study of rocks, their origin, composition, and physical and chemical properties, as well as the distribution of the Earth's crust. This branch of geology is called petrology. The term petrology comes from the practical word petro, meaning stone, and logos, meaning study. There are differences with lithology, which focuses on the rock composition of a given area. In petrology, the study of petrogenesis. It is about the origin of the rocks.
In this article we are going to tell you all the characteristics, origin and studies of petrogenesis.
Key features
Petrology is divided into several specialized areas depending on the type of rock to be studied. Therefore, there are two branches of the division of studies that are the petrology of sedimentary rocks and the petrology of igneous rocks and metamorphic. The first is known as exogenous petrology and the second as endogenous petrology. There are also other branches that vary depending on the objective proposed for the study of rocks. There is also a type of petrography for the description of rocks and the petrogenesis to determine its origin.
Petrogenesis is an important aspect since it encompasses the formation and origin of rocks. Similarly, there is another applied petrology that focuses on the biological properties of rocks. It should be noted that a thorough understanding of the biological properties of rocks can be applied in many crucial areas, including construction and resource extraction for humans.
Therefore, this branch of science is extremely important since rock constitutes the fundamental support of all human physical structuresIt is important to understand the structure, origin, and composition of the rocks on which we deposit and build our infrastructure. Before undertaking any type of construction of buildings, infrastructure, etc., a prior study of the types of rocks that exist at the base of the structure must be conducted to prevent possible subsidence, flooding, disasters, collapses, etc. Rocks are also an essential raw material for much of human industrial activity. You can learn more about the different types of rocks in this article. types of rocks.
Origin of petrology and petrogenesis
The interest in rocks has always been present in the human being. It is a constant element in the natural environment that has made technology develop since prehistoric times. The first human tools were made of stone and gave rise to an entire age. It is known as the Stone Age. The contributions to be able to know the uses of the rocks have been especially advanced in China, Greece and the Arab culture. The western world highlights the writings of Aristotle where they talk about their usefulness.
However, although humans have been working with the earth since prehistory, the origin of petrology as a science is closely linked to the origin of geology. Geology is the parent science and was consolidated in the 18th century, when its principles began to be established. Petrology stems from a scientific controversy that developed over the origin of rocks. This controversy gave rise to two factions known as Neptunists and Plutonists.
Neptunists are those who argue that rocks originate through the sedimentation of sediments and crystallization of minerals from the ancient ocean that covered the entire planet. For this reason, they are known by the name of Neptunists, alluding to the Roman God of the oceans Neptune. On the other hand we have the Plutonists. They think that the origin of rocks begins from magma in the deepest layers of our planet caused by high temperatures. The name of Plutonists comes from the Roman God of the underworld Pluto.
Modern knowledge and technological developments allow us to understand that both positions could explain reality. Sedimentary rocks arise through processes related to the intuitions held by Neptunists, while igneous, volcanic, plutonic, and metamorphic rocks originate in processes that coincide with the arguments of Plutonists. For more information on rock formation, you can visit the article on how rocks are formed.
Petrology Studies
Once we understand the origins and different approaches to petrology, let's look at the objectives of the study. It covers the entire origin of rocks and everything related to their structures. These include the origin, the processes that generate them, the location in the lithosphere where they are formed, and their age. It is also responsible for studying the physical and chemical components and properties of rocks. The last, no less important, area of study is the distribution and petrogenesis of the rocks in the Earth's crust.
Within petrology, the petrogenesis of extraterrestrial rocks is also studied. These are all rocks originating from outer space. In fact, rocks originating from meteorites and the moon are currently being studied. This includes research on asteroids which could have been fragments of the moon.
Types of petrogenesis
As we mentioned before, there are several branches of this science, and they are classified into three petrogenesis processes that give rise to rocks: sedimentary, igneous, and metamorphic rocks. Therefore, depending on the area of origin of each rock type, there are two branches of petrology:
- Exogenous: It is responsible for studying all rocks that originate in the shallowest layers of the Earth's crust. In other words, it studies sedimentary rocks. These types of rocks are formed from the compression of sediments after their deposition and transport by geological agents such as rain and wind. These sediments are deposited over millions of years. This occurs especially at lower altitudes, such as lakes and oceans. Successive layers crush and compress the sediments over millions of years. To learn more about the characteristics of sedimentary rocks, don't miss the article on sedimentary rocks.
- Endogenous: It is responsible for studying the types of rocks that form in the deepest layers of the Earth's crust and mantle. Here we have igneous rocks, both volcanic and plutonic, and metamorphic rocks. In the case of igneous rocks, they rise due to internal pressure through cracks and cool, forming rocks. If they come to the surface from volcanic eruptions, they are volcanic rocks, which are explained more in the article on igneous rocksIf they are formed inland, they are plutonic rocks. Metamorphic rocks originate from igneous or sedimentary rocks that have been subjected to great pressures and temperatures. Both types of rocks form at great depths. All these conditions generate changes in their structure and composition.
I hope that with this information you can learn more about petrogenesis and its types.