Origin of Igneous Rocks

The video tutorial explores the formation and classification of rocks, focusing on igneous rocks. It explains how minerals and rocks form due to environmental factors like pressure and temperature. The process of decompression melting and flux melting is detailed, highlighting their roles in volcanism. The crystallization sequence of minerals in cooling magma is discussed, using Bowen's reaction series as a model. The concept of differentiation is introduced, explaining how magma composition changes as it cools, with examples from Hawaii and Yellowstone.

What are the two terms used by geologists to describe molten rock, depending on its location?

• Magma and Lava

• Mantle and Crust

• Igneous and Sedimentary

• Basalt and Granite

Which process is responsible for the majority of Earth's volcanism?

• Flux Melting

• Convection Melting

• Decompression Melting

• Subduction Melting

What is the role of hydroxide anions in flux melting?

• They increase the melting point of mantle rock

• They decrease the melting point of mantle rock

• They solidify the mantle rock

• They have no effect on the melting point

Why do volcanoes occur in a line or arc at subduction zones?

• Due to the presence of magma chambers

• Because of the release of hydroxide anions

• Because of the high temperature of the mantle

• Due to the movement of tectonic plates

What is the first mineral to crystallize according to Bowen's reaction series?

• Olivine

• Quartz

• Amphibole

• Biotite

Which mineral is most abundant in the Earth's crust and can exist at all stages of Bowen's reaction series?

• Biotite

• Olivine

• Plagioclase

• Quartz

How does the crystallization of olivine affect the composition of the remaining melt?

• Depletes in aluminum

• Enriches in magnesium

• Enriches in silica

• Depletes in silica

What happens to the melt as olivine crystallizes and sinks in the magma chamber?

• It becomes enriched in silica

• It becomes depleted in aluminum

• It becomes enriched in magnesium

• It becomes depleted in silica

What is the main factor that influences the amount of differentiation a magma undergoes?

• Temperature of the magma

• Type of minerals present

• Thickness of the crust

• Presence of water

What is the primary difference between the volcanic activity at Hawaii and Yellowstone?

• Hawaii erupts basaltic lava, Yellowstone erupts felsic magma

• Yellowstone has more frequent eruptions than Hawaii

• Yellowstone is beneath oceanic crust, Hawaii is beneath continental crust

• Hawaii has explosive eruptions, Yellowstone does not