ELS-Q1-M7- The Process of Magmatism.pptx

The Process of Magmatism
Magmatism is the process of magma formation, movement, and solidification, which plays a central role in shaping Earth’s crust through volcanic activity and the formation of igneous rocks. It occurs in both intrusive and extrusive environments and is driven by internal heat and pressure within the Earth.

Stages of Magmatism
Magma Generation
Magma Ascent and Migration
Magma Storage and Differentiation
Magma Crystallization and Solidification
1. Magma Generation
Magma forms when rocks in the Earth's mantle or lower crust melt due to one or more of the following conditions:

Decompression Melting:

Occurs when pressure decreases as rock rises toward the surface, reducing the melting point.
Common at divergent boundaries (e.g., mid-ocean ridges) and hotspots.
Flux Melting:

Occurs when water or other volatiles are added to hot rocks, lowering their melting point.
Common at subduction zones, where oceanic crust releases water into the mantle.
Heat Transfer Melting:

Occurs when rising magma transfers heat to surrounding rocks, causing them to melt.
This happens near hotspots or in regions of intense volcanic activity.
2. Magma Ascent and Migration
After forming, magma is less dense than the surrounding solid rock, causing it to rise toward the surface through fractures or along weak zones in the crust. This process is known as magma ascent.

Pathways for Magma Migration:
Dikes: Vertical intrusions of magma.
Sills: Horizontal intrusions of magma.
The ascent of magma depends on several factors:

Viscosity (resistance to flow): Silica-rich magmas (e.g., rhyolite) are more viscous, slowing down ascent.
Temperature: Hotter magmas flow more easily.
Pressure and gas content: Trapped gases help drive magma upward.
3. Magma Storage and Differentiation
Magma can accumulate in magma chambers within the crust before reaching the surface. While stored, several processes occur:

Fractional Crystallization:

Minerals crystallize out of the magma as it cools, changing the chemical composition of the remaining magma.
Assimilation:

Magma incorporates surrounding rock material, altering its composition.
Magma Mixing:

Two different magmas may mix, producing hybrid compositions.
This stage determines the type of igneous rock that will form (e.g., basalt, andesite, or granite).

4. Magma Crystallization and Solidification
Depending on where and how the magma solidifies, it can form different types of igneous rocks.

Intrusive (Plutonic) Rocks:

Magma solidifies beneath the surface, cooling slowly to form coarse-grained rocks (e.g., granite, diorite).
Extrusive (Volcanic) Rocks:

Magma erupts as lava and cools quickly on the surface, forming fine-grained rocks (e.g., basalt, rhyolite).
Volcanic Eruption:

If gases trapped in the magma are released violently, explosive eruptions occur, producing volcanic rocks like pumice and tuff.

1. MAGMATISM After going through this module, you are expected to : 1. describe the characteristics of magma; 2. identify the substances/elements present in magma; and 3. explain the processes involved in the formation of magma.

2. Activity 1: Picture Analysis Observe the picture of Mount Mayon and answer the following: Give three (3) descriptions about the picture . What is the material being extruded by Mount Mayon? Where do you think did this material come from?

3. What is Magma? Magma is composed of semi-liquid hot molten rocks located beneath the Earth, specifically in the melted mantle rock and oceanic plate. This molten state, when solidified, creates igneous rocks found on the surface of the Earth.

4. What is Magma? Magma and lava are both molten rocks. However, they differ in location. Magma is found inside the magma chamber of the volcano while Lava is found on the surface of earth once the volcano erupts.

5. What is Magmatism? - is a process under the earth’s crust where formation and movement of magma occur. -These happen in the lower part of the Earth’s crust and in the upper portion of the mantle, known as asthenosphere.

6. Composition of Magma Guide Questions: 1. Which of the following elements has the highest amount in the magma? 2 . Which of the following elements has the lowest amount in the magma? 3 . What are the top two compositions of magma?

7. The magma present in the lower crust and upper mantle of the Earth is formed or generated through the process of partial melting. In this process, different minerals in rock melt at different temperature and pressure. How Magma is formed?

8. Another factor being considered in this process is the addition of volatile materials such as water and carbon dioxide.. How Magma is formed?

9. How Magma is formed?

10. Melting in the mantle requires one of three possible events to occur : 1. AN INCREASE IN TEMPERATURE: Conduction in mantle happens when heat is transferred from hotter molten rocks to the Earth’s cold crust. This process is known as heat transfer. It happens at convergent boundaries , where tectonic plates are crashing together.

11. Melting in the mantle requires one of three possible events to occur : 1. AN INCREASE IN TEMPERATURE: Conduction in mantle happens when heat is transferred from hotter molten rocks to the Earth’s cold crust. This process is known as heat transfer. It happens at convergent boundaries , where tectonic plates are crashing together.

12. Melting in the mantle requires one of three possible events to occur : 2. A DECREASE OF PRESSURE: Mantle rocks remain solid when exposed to high pressure. However, during convection, these rocks tend to go upward and the pressure is reduced. This triggers the melting of magma. This is known as decompression melting . This process occurs at the Mid-Ocean Ridge , an underwater mountain system.

13. Melting in the mantle requires one of three possible events to occur : 2. A DECREASE OF PRESSURE: Mantle rocks remain solid when exposed to high pressure. However, during convection, these rocks tend to go upward and the pressure is reduced. This triggers the melting of magma. This is known as decompression melting . This process occurs at the Mid-Ocean Ridge , an underwater mountain system.

14. Melting in the mantle requires one of three possible events to occur : 3. ADDITION OF VOLATILES: When water or carbon dioxide is added to hot rocks, flux melting occurs. The melting points of minerals within the rocks decrease. If a rock is already close to its melting point, the effect of adding these volatiles can be enough to trigger partial melting. It occurs around subduction zones.

15. Melting in the mantle requires one of three possible events to occur : 3. ADDITION OF VOLATILES: When water or carbon dioxide is added to hot rocks, flux melting occurs. The melting points of minerals within the rocks decrease. If a rock is already close to its melting point, the effect of adding these volatiles can be enough to trigger partial melting. It occurs around subduction zones.