Igneous Rocks and Formation Processes

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What is the characteristic feature of obsidian?

Phaneritic texture

Rich in olivine

Vesicles

Glassy texture (correct)

Which rock is considered the mafic counterpart of pumice?

Scoria (correct)

Gabbro

Basalt

Obsidian

What is the main difference between gabbro and basalt in terms of mineral composition?

Gabbro has aphanitic texture.

Basalt has a glassy texture.

Gabbro contains minor amounts of olivine & amphibole. (correct)

Basalt forms at mid-oceanic ridges.

How do the crystal sizes of intrusive rocks compare to extrusive rocks?

Intrusive rocks have larger crystals due to longer cooling time. Signup and view all the answers

What process leads to the formation of vesicles in rocks like pumice?

Trapped gas bubbles expanding Signup and view all the answers

Which rock is an extrusive felsic rock formed from extremely rapid cooling?

Pumice Signup and view all the answers

What is the main factor that determines the composition of magma?

The type of minerals present in the source rock Signup and view all the answers

Which of the following is not a common sedimentary structure?

Foliation Signup and view all the answers

What is the primary driver of the formation of sedimentary rocks?

Weathering and erosion of pre-existing rocks Signup and view all the answers

Which of the following is not a common igneous rock?

Gneiss Signup and view all the answers

What is the main driver of the formation of metamorphic rocks?

Changes in temperature and pressure Signup and view all the answers

Which of the following is a common sedimentary structure that indicates the direction of water flow?

Cross-bedding Signup and view all the answers

What is the main source of sediment for the formation of sedimentary rocks?

Biological origin, other rocks, or evaporites Signup and view all the answers

Which of the following processes is responsible for the formation of magma?

Decreasing pressure Signup and view all the answers

What differentiates extrusive igneous rocks from intrusive igneous rocks?

Extrusive rocks cool at the Earth's surface Signup and view all the answers

What is the role of volatiles in the formation of magma?

They trigger the melting process Signup and view all the answers

What type of boundary is typically associated with decompression melting?

Divergent plate boundary Signup and view all the answers

What is the major difference in the formation of sedimentary rocks and metamorphic rocks?

Metamorphic rocks form from heat and pressure Signup and view all the answers