PETROLOGY: WHAT IT STUDIES, BRANCHES AND IMPORTANCE - GEOGRAPHY - 2025

The petrology is a branch of geology that studies rocks and the conditions under which they originate. In his studies, he uses mineralogy, petrography and chemical analysis to be able to describe both the structure and the texture and composition of rocks.

Petrological studies deal with the three main types of rocks that exist: igneous, sedimentary, and metamorphic. Other sub-disciplines are included within petrology, such as experimental petrology and petrography. The latter is fundamentally based on the principles and methods used by mineralogy.

In addition, many rocks harbor important minerals; very important raw materials for life and technological development are obtained from these.

What does petrology study?

The etymology of the word petrology derives from a combination of the Greek words petra, which means "rock," and logos, which means, "treatise" or "knowledge."

Petrology is the scientific study of rocks and deals with analyzing their composition, texture and structure. It also addresses the study of the formation and distribution of rocks, as well as the origin of rocks associated with the prevailing physicochemical conditions and the geological processes in which they take place.

In short, it is considered a scientific field of geology that deals with the origin, occurrence, structure, chemical composition, history and classification of rocks. Petrology deals with the study of the three main groups or types of rocks that exist: igneous, sedimentary and metamorphic.

To describe the structure and composition of rocks, he uses the classic fields of mineralogy, petrography and chemical analysis. Modern petrology studies employ the principles of geochemistry and geophysics to better understand how rocks originate.

Thanks to the work of petrologists, it has been possible to expand and advance the knowledge of igneous and metamorphic processes in rocks.

Petrology and mineralogy

Petrology and mineralogy are fields or branches of geology that provide very valuable scientific information. The two fields should not be confused, since mineralogy deals with the study of minerals, their properties, crystallography, classification and ways of distinguishing them.

However, petrology does rely on the principles and methods of mineralogy to a large extent for two basic reasons: most rocks are made up of minerals and their formation occurs under more or less the same conditions.

Careful mapping and sampling of rock units is considered essential for optimal development of petrological research, in order to obtain relevant and specific data on regional gradations of rock types and on associations that are not available by other media.

Branches of Petrology

Petrology is divided into three branches, each of which corresponds to the three types of rocks that exist: igneous, metamorphic, and sedimentary. In addition, there is another branch that deals with experimental techniques.

Igneous Petrology

It focuses on the study of the composition and texture of igneous rocks, which are basically volcanic and plutonic rocks. This type of rock, such as granite or basalt, is formed when molten rock or magma crystallizes.

Sedimentary petrology

This branch focuses on the study of the composition and texture of sedimentary rocks. These types of rocks are sandstones, shales or limestone, which are pieces or particles of rock originating from other rocks.

Sedimentary rocks also form from biological or chemical deposits, and are almost always held together by finer material.

Metamorphic Petrology

As its name indicates, it is oriented to study the composition and texture of metamorphic rocks. These are slate, marble, gneiss or schists, which although they are sedimentary or igneous rocks, over time underwent chemical, mineralogical or texture changes as a consequence of extreme degrees of temperature, pressure or both.

Experimental Petrology

In this branch of petrology, high-pressure and high-temperature equipment is used to investigate the geochemistry of rocks. Likewise, the phase relationships of materials, whether natural or synthetic, subjected to very high temperatures and pressures are investigated.

This type of experiment is particularly useful, because it is used to investigate rocks found in the lower crust and in the upper mantle. These rocks rarely survive the journey to the surface in their natural or primeval conditions.

Petrography

It is considered a branch of petrology and deals with the study of mineral content and the texture relationships found within rocks. The word petrography also comes from the Greek petros, which means "stone"; and graphs, which means "description."

Petrography describes the appearance of rocks, their mineralogical composition and, especially, their structure on a microscopic scale.

The term "lithology" was previously used as a synonym for petrography, but today it has a different meaning. Today it is considered rather a subdivision of petrology; Its object of study is the macroscopic description of the rock sample by hand or on an outcrop scale.

Importance

The study of rocks is very important for several reasons, namely:

- Through this study it is possible to know what minerals and chemical elements the rocks are composed of, and from these data information is obtained about the composition of the earth's crust and the mantle.

- The ages of the Earth can be calculated through various methods of radiometric dating. From there a chronological sequence of geological events can be established.

- The characteristics of the Earth are usually the same characteristics of a specific tectonic environment. With this information, scientists can reconstruct these tectonic processes.

- The study of the rock layers that are found below the earth's surface helps to better understand the history of the Earth.

- Many rocks contain minerals that are very important. These provide human beings with valuable raw materials on which their livelihoods and technological development depend.

References

1. Petrology. Retrieved March 26, 2018 from web.newworldencyclopedia.org
2. The Branches of Geology. Consulted from courses.lumenlearning.com
3. What is Petrology. Consulted from igi-global.com
4. Mineralogy & Petrology. Retrieved from geology.byu.edu
5. Petrology. Consulted of planetary-science.org
6. Petrology. Consulted of nature.com
7. Petrology. Consulted from britannica.com