The Metamorphic rocks They are a group of rocks that formed due to the presence of other materials within the Earth, all through a process called metamorphism. Their transformation was the result of a series of mineralogical and structural adjustments that transformed the original rock into a metamorphic rock. Based on their origin, they can be classified as igneous or metamorphic rocks, from which they were born. The study of these rocks provides valuable information about all the geological processes that take place on Earth and how they can change over time. Additionally, you can learn more about how other rocks form on our page about rock formation.
In this article, we're going to tell you about the characteristics, formation, and origin of metamorphic rocks.
Key features
Metamorphic rocks are altered by thermal, pressure, and chemical processes. Usually buried well below the surface. Exposure to these extreme conditions has altered the rock's mineralogy, texture, and chemical composition. There are two basic types of metamorphic rocks: Metamorphic rocks
- foliate such as gneiss, phyllite, shale, and slate, which develop a layered or banded appearance due to heating and directional pressure; Y
- not foliated such as marbles without leaves and quartzites without the appearance of layers or bands.
Metamorphic rocks are probably the least known and are often confused or associated with others by those who are not experts in geology and petrology. However, These rocks are not only very abundant in the earth's crust, but are also the product of choice for numerous geological and tectonic phenomena, such as mountain building. To understand their formation, it is important to study the types of rocks in general.
The study of metamorphic rocks is of fundamental importance to understand the geological evolution of the earth. Also, this should be of great interest to mineral collectors, metamorphic rocks represent a typical geological environment where many highly sought after mineral species can be found, such as garnet and beryl. The set of all the phenomena that cause rocks to transform into new rocks is called metamorphism, a term derived from the Greek word meaning .
metamorphism in metamorphic rocks
Metamorphic rocks are formed by solid-state recrystallization of pre-existing rocks, either on large or local scales, as a result of high pressures and/or high temperatures occurring under specific conditions and as a result of specific geological processes. In this regard, it is interesting to understand the processes of petrogenesis.
This means that when any type of rock (whether igneous, sedimentary, or metamorphic) solidifies, it is in very different physicochemical conditions than the original rock. it was in balance, creating a new type of rock… This will differ from the original in structure, texture, mineralogy, and sometimes chemical composition (when the action of the mineral-rich leachate also interferes with metamorphism).
regional metamorphism
Regional metamorphism occurs when rocks are brought to great depths relative to where they originated. The extent of regional metamorphism is completely dependent on depth, since temperature and pressure increase with depth. Rocks with the same initial composition and increasingly pronounced transformations They form a metamorphic series in which we find, as an example, clays that form other rocks. For example, a rock of low-zone metamorphism is slate, which forms parallel planes after metamorphism. Other examples are quartzites and igneous rocks, which can also be related to the igneous rocks.
contact metamorphism
This type of metamorphism occurs when rocks are overtaken by magma that rises from deeper regions to the surface. This is why it's called "contact." It's essential to understand how this process relates to the formation of other rocks.
This process usually involves the recrystallization of existing minerals, which they acquire new structures and dimensions. This is due to the fluidity that the mineral acquires as the temperature increases. Marble is an example of such a rock and it is important to mention its relationship with the plutonic rocks.
fission metamorphism
A third type of metamorphism occurs in surface rocks that are compressed when the movement of the Earth's crust forces them toward each other. The degree of metamorphism depends on the intensity of the pressure. Occasionally, new, larger minerals form; in these examples, we find mylonite.
Utilities of metamorphic rocks
The process of metamorphism causes many changes in these rocks, among which are the increase in density, the enlargement of crystals, the reorientation of mineral grains and the transformation of low-temperature minerals into high-temperature minerals. These criteria are which rocks can be classified, but we are going to explain each characteristic of these rocks, generally we will talk about the most common rocks, since there is a wide variety of rocks in this group, we will start with this:
- Slate and phyllite: This rock has a very fine to fine grained texture. It is mainly composed of layered silicates and quartz; feldspar is also frequently present. Due to the orientation of the phyllosilicates, the rocks are foliated and prone to fission. They are rocks that are not used today, but have been used for waterproofing roofs.
- Shale: This rock has a medium to coarse grained texture with pronounced foliation, and the mineral grains in this case can be distinguished with the naked eye. The use of this type of rocks is in construction, since they are very strong and durable. Its sources can be clays and muds, including intermediate processes.
- Gneiss: Its origin is the same as the granite minerals (quartz, feldspar, mica), but it has a zonal orientation, and the light and dark tones that the minerals cause are also the product of the metamorphism of igneous and sedimentary rocks. Its use is also concentrated in architecture, especially in the formation of pixelated damage, cobblestones, etc.
- Marble: The texture of this rock ranges from fine to thick, its origin is from limestone to crystallization, this rock can originate from processes such as metamorphism, magma, hydrothermal, sedimentation, etc. Additionally, calcium carbonate imparts various colors to marble and defines its physical properties. Its uses range from decorative to having been used in art and archaeology.
- Quartzite: As its name indicates, this rock is mainly composed of quartz minerals and has a non-leafy structure, obtained as a shale structure due to recrystallization at high temperature and pressure. Its uses are in metallurgical processes and in the manufacture of silica bricks, other uses are decorative rocks in architecture and sculpture.
I hope that with this information you can learn more about the Metamorphic rocks and their characteristics.
