Petrology

Today we are going to talk about a branch of geology that focuses on studying rocks as a whole. It's about the petrology. The main objective of this branch of science is to study the geometric field characteristics, the petrographic characteristics, the components, the detailed chemical composition and the different minerals that make up the rocks. It is of great importance for the study of the different geographical areas that make up ecosystems.

In this article we are going to tell you about all the characteristics, studies and objectives of petrology.

Key features

When we talk about petrology we are focusing on the study of rocks as a whole. Try to identify the conditions physicochemical processes of rock formation and what are the evolutionary processes that take place during their genesis. There are numerous petrographic studies that address the physical description in visual terms of all rocks. To do this, it uses polarized light microscopy, which is essentially using transmitted light, although it is also reflected in some cases. All these studies offer a great deal of information about the nature of the rock components, essentially minerals, their abundance, shape, size and spatial relationships.

All these characteristics help to classify the rocks and establish all the qualitative and quantitative conditions of their formation. Some rocks have been created with various evolutionary processes that are also identified in petrology. Petrographic components are those that make up the rock and that have a physical entity. These components are the mineral grains, the particular associations of some minerals and other rock fragments that are genetically related or not. Some occur in all types of rocks such as mineral grains or pores. These are more abundant in sedimentary rocks and volcanic igneous rocks. However, they are more rare in metamorphic rocks and plutonic igneous rocks.

Some of them occur in only some types of rocks such as volcanic glass located in volcanic magmatic rocks. Others occur only occasionally, such as fractures.

Mutual spatial relationships in petrology

Today we are going to distinguish the different concepts of mutual spatial relationships in petrology. The first is the texture. It is the set of intergranular spatial relationships and the morphological characteristics of the rocks. This is where the grains present in the rock and mineral aggregates enter. It could be said that the components of the rock are those that give it its morphological characteristics. The designations in the structure and the criteria used to identify these components vary depending on the type of rock to be studied.

There are numerous types of spatial relationships within petrology, although 5 more basic textural types can be established that serve all natural rocks. Let's see what are the different types of textures and combinations that are most commonly found:

• Sequential texture: It is also known as a serial texture and is one in which the rock is made up of crystals that have grown from a liquid solution. An example of this is through magma or some fluids. Rock crystals grow at different times and therefore have different morphological characteristics. This type of texture is applicable to all types of rocks, although it is more typical of plutonic igneous rocks and volcanic and some sedimentary rocks.
• Vitreous texture: It is a texture that reflects those rocks that are totally or partially made of glass and are formed by the rapid solidification of a magmatic melt. It is more typical of volcanic igneous rocks.
• Clastic texture: is that which is formed by fragments of rocks and minerals that are included or not within a finer, precipitated and/or recrystallized material. This texture is applied to the detrital sedimentary rocks, although some volcanic rocks also contain them. Fragments of rocks and minerals are called clasts.
• Blast texture: It is one that is made up of crystals that have formed in a solid medium. It has been generated through the transformations of existing minerals. This type of texture is usually found more specifically in metamorphic rocks. The recrystallized mineral grains are called blasts.

Petrology and crystallography

When defining the scope of work of petrology and crystallography, we see that there are some concepts in common. And it is that the spatial orientation that we have mentioned previously of all the components and the crystallographic elements of the minerals within a rock, are studied in both branches. Let's see what must be taken into account for the determination of the crystallographic factory and the existing types:

• Isotropic: It is one in which there is no preferential orientation of the components.
• Linear: It is one in which the orientation of the components has a predominant direction.
• planar: This is the orientation in which the components are in one plane.
• Plane-linear: It is the orientation of the components in one direction and within the same plane.

We generally find the rocks deformed, so the original components that were already equidimensional have been able to stop being so. Normally, they cease to be due to plastic deformation. Said deformation comes from the pressure so that its components are subjected. Most of the metamorphic rocks present varied factories. In the case of some marbles we see that they present preferential morphological and crystallographic orientations of the calcite grains. On the other hand, the preferential limitation of other components does not have to be due to deformation in the solid state.

We often find a clearly bimodal size relationship between the solid components in different types of rocks. Eta means that some have a coarser grain size than othersThe population of all the finer components is called the matrix. This concept has different connotations depending on the rock to which it is applied. On the other hand, the concept of cement applies more specifically to the sedimentary rocks link that have been altered in any way.

I hope that with this information you can learn more about petrology and its characteristics.