Identifying Igneous Rocks Through Their Characteristics and Classification

The video tutorial explores the classification of igneous rocks, distinguishing between extrusive and intrusive types. Volcanic rocks are classified by silica content, with examples like rhyolite and basalt. Plutonic rocks are named based on mineral composition using diagrams. The video also discusses where different igneous rocks are found, such as basalt at mid-ocean ridges and andesite in subduction zones.

What is the primary difference between extrusive and intrusive igneous rocks?

• Extrusive rocks cool quickly at the surface.

• Intrusive rocks cool quickly at the surface.

• Intrusive rocks are formed during volcanic eruptions.

• Extrusive rocks cool slowly at depth.

Which of the following volcanic rocks has the highest silica content?

• Basalt

• Rhyolite

• Andesite

• Pichrite

What term is used to describe rocks with less than 45% silica content?

• Ultramafic

• Intermediate

• Mafic

• Felsic

Which mineral is NOT typically found in rhyolite?

• Sodium-rich plagioclase

• Quartz

• Olivine

• Alkali feldspar

How are plutonic igneous rocks named?

• Based on their three most abundant minerals

• Based on their color

• Based on their silica content

• Based on their cooling rate

What is the plutonic equivalent of basalt?

• Diorite

• Cyanite

• Granite

• Gabbro

Which diagram is used to classify felsic plutonic rocks?

• Mafic diagram

• QAP diagram

• Silica diagram

• Mineral diagram

Where is basaltic lava most commonly found?

• Mid-ocean ridges

• Hotspots beneath continental crust

• Continental arcs

• Subduction zones

What type of magma is typically produced at subduction zones?

• Ultramafic

• Rhyolitic

• Andesitic

• Basaltic

Which type of volcanic arc tends to produce rhyolite and dacite?

• Hotspots

• Continental arcs

• Mid-ocean ridges

• Island arcs