February 26, 2021

Metasomatism: Difference Between Metasomatism and Metamorphism

Metasomatism is really one of the most important topics in the context of geology. The students of geology and mining engineering are well aware of this word. In this article, we will discuss what is metasomatism and what is the basic difference between metasomatism and metamorphism? Before we go on an article we will discuss what is metasomatism?

What is Metasomatism?

We can define metasomatism as a “metamorphic process of the forming new minerals by the mechanism of chemical replacement of the pre-existing mineral under the influence of chemically active fluids.” 

As we all know that rocks that are available in the pre-existing form undergo some physical and chemical changes when it comes in contact with the surrounding environment. The changes that actually happen in the pre-existing rocks are quite noticeable and it may change the whole structure of the original rock. Hence this topic is widely discussed in the context of Geology and many geologists are still studying the same.

The one thing that I can tell you in the metasomatism process is that the changes that happen in the pre-existing rock can happen in two-state.

  1. Atomic-level and 
  2. Solid-state.

So when discussing the same thing deeply we can write the following changes as under. I am quite sure that you are actually wondering how this change happens in rocks? (I am sure you are certainly looking for this article, that’s why you are here.. Don’t make me a fool…Okay Sorry.. Let’s continue.)

Difference between metsasomatism and metamorphism Metasomatism: Difference Between Metasomatism and Metamorphism

What Causes Metasomatism?

As we all know that there are lots of pores that available in the original rock composition. When the fluids like magma and lava pass in the rock through these pores then it might have abilities to change the whole structure of the rocks. There is also the chance of atomic replacement during this process. (you must have a huge knowledge about the chemical composition of the rocks to understand this.)

When these atomic structures change then they might have chances of forming new minerals. But if the whole chemical composition of the rocks remains unchanged then it is actually metasomatism that happens in the atomic-state. This is one of the most important types of metasomatism in geology. This metasomatism change happens in the inside of the rock bodies. It is also known as internal metasomatism changes.

Now, Moving forward, I know what are you wondering. Then how changes can happen outside the rocks?

Imagine if the rocks didn’t have any pores or any kinds of faults that are not available in their structure. Then what happens in this type of rock is that if this rock is when it comes in contact with the groundwater then this water is capable of the biggest level changes in the rocks.

There might have chances of the formation of the new minerals which have completely different atomic structure. The changes that happen in solid-state during the metasomatism process have huge chances to change the whole composition of the rock as a whole. This type of change that happens in the solid-state of the rock bodies also referred to as the “Rock metasomatism”.

The process of metasomatism is furtherly distinguished in the following parts.

  1. Hydrothermal – When the fluids are in the form of a solution.
  2. Additive – When the net result of the process in an addition to new constituents.
  3. Expulsive – When some components get removed from the original composition of the rocks.

The one most important thing about the metasomatism process is that the total composition of the rock remains unchanged after the process is completed. There might be some drastic changes but at the end of the process, its composition remains unchanged.

You can observe the metasomatism process in silicate and carbonate minerals quite easily.

Difference between Metamorphism and Metasomatism. 

As of now, I am quite sure that you are actually looking for what is the actual difference between metamorphism and metasomatism. That is a really very small difference between both the process. I am here going to further explain to you the same.

Metamorphism is the process that actually used when all the changes that happen in the original rocks under the influence of the changes in the surrounding conditions like temperature, pressure, and chemically active fluids. All three components are also referred to as the “Agents of the metamorphism”.

We simply can say that metamorphism is the actual process of the changes in the mineral composition due to the physical factors of the metamorphism like temperature, pressure, and chemically active fluids. The groundwater plays a less major role in the composition that takes changes.

On the other hand, we can say metasomatism is the process of changing a rock’s composition in an open system. A system in which mass can enter and leave. Unlike the physical change, groundwater plays a major role in the composition of the rocks.

The metasomatic process involves changes in the rock’s minerals by replacement from the outside. when a rock is hot enough ions will migrate into and out of the rock. This can generally happen around igneous intrusions. The metamorphic changes generally happen within the rocks. Under the heat and pressure, the mineral will crystalize to form new ones that are stable under those conditions. It is the same atoms that actually take part in the new place to form a  new mineral.

‘We hope you liked this article.

 

 

 

 

 

 

 

 

 

 

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