What is magma and how is magma formed? | The difference between magma and lava

Summary

In this video, viewers learn about magma—its composition, types, and how it forms. Magma, a hot mixture of molten rocks, is classified into three types: basaltic, andesitic, and rhyolitic, each with different silica content, gas levels, and viscosity. The video explains how magma forms through processes like partial melting, decompression melting, and flux-induced melting. It also highlights the difference between magma and lava, emphasizing that lava is magma that has reached the Earth's surface. The video invites viewers to explore more about Earth’s geological wonders in future content.

Takeaways

• 🌋 Magma is a hot mixture of molten and semi-molten rocks flowing deep beneath the Earth's surface.
• 💡 Magma consists of inorganic components like minerals, rocks, and dissolved gases embedded in the hot liquid base (melt).
• 🧪 There are three types of magma: basaltic, andesitic, and rhyolitic, classified by their silica content and other minerals.
• 🔥 Basaltic magma has the lowest silica content, highest temperature, lowest gas content, and lowest viscosity among the three types.
• 🧱 Andesitic magma has moderate silica content, moderate temperature, moderate gas content, and higher viscosity compared to basaltic magma.
• ⛰️ Rhyolitic magma has the highest silica content, the lowest temperature, highest gas content, and highest viscosity.
• 🌍 Magma forms deep beneath the Earth’s surface, typically in the lower crust and upper mantle, through partial melting, decompression melting, or flux-induced melting.
• 🔄 Decompression melting occurs when mantle rocks move upward, reducing pressure, and causing the rocks to melt without changing temperature.
• 💧 Flux-induced melting happens when substances like water lower a rock’s melting point, causing it to melt more easily.
• 🔥 The key difference between magma and lava is that magma becomes lava once it reaches the Earth's surface, typically during volcanic eruptions.

Q & A

What is magma?

Magma is a hot, viscous material made up of molten and semi-molten rocks, minerals, and dissolved gases, found deep beneath the Earth's surface.

What are the main types of magma?

The main types of magma are basaltic magma, andesitic magma, and rhyolitic magma, classified based on their silica content and other chemical properties.

What is the difference between basaltic, andesitic, and rhyolitic magma?

Basaltic magma has the lowest silica content (45-55%), high in iron, magnesium, and calcium, and low viscosity. Andesitic magma has a moderate silica content (55-65%) and viscosity, while rhyolitic magma has the highest silica content (65-75%) and viscosity, with lower levels of iron, magnesium, and calcium.

Where does magma originate from?

Magma originates from deep beneath the Earth's surface, in the lower crust and upper mantle, where high pressures and temperatures cause rocks to melt.

How is magma formed through partial melting?

Partial melting occurs when only some minerals in a rock melt due to differing melting points of the minerals, with the ones with lower melting temperatures melting first.

What is decompression melting and how does it form magma?

Decompression melting occurs when rocks in the mantle move upward, experiencing lower pressure, which allows them to melt even without a change in temperature.

What is flux-induced melting?

Flux-induced melting happens when certain elements, like water or carbon dioxide, lower the melting point of rocks, enabling them to melt and form magma.

What is the difference between magma and lava?

Magma is the molten rock beneath the Earth's surface, while lava is magma that has reached the Earth's surface through a volcanic eruption or vent.

What are the characteristics of basaltic magma?

Basaltic magma has low silica content, low viscosity, high temperature, and contains high levels of iron, magnesium, and calcium, making it the least gaseous of the three magma types.

Why does magma remain in a fluid state?

Magma remains fluid due to a combination of high temperature and pressure conditions found deep within the Earth's mantle and lower crust.