Geology Ch. 6 Notes + Flashcards

Igneous Rocks

Rocks formed through the solidification of molten minerals, often referred to as "born of fire."

Mafic Rocks

Igneous rocks with lower silica content

Felsic Rocks

Igneous rocks with higher silica content

Sedimentary Rocks

Rocks formed from the lithification of transported rock debris by erosion agents.

Metamorphic Rocks

Rocks formed from pre-existing rocks exposed to high heat and pressure, leading to a change in form.

Intrusive Rocks

Igneous rocks that cool below the surface, characterized by large crystals and phaneritic texture.

Extrusive Rocks

Igneous rocks that cool on the surface, resulting in small crystals and aphanitic texture.

Magma

Molten rock beneath the Earth's surface that can change in composition through processes like fractional crystallization.

Vesicular Rocks

Igneous rocks filled with air pockets or vesicles, such as pumice and scoria.

Creation of Igneous rock

Can form 50-250km below the surface at temperatures over 800 degrees C

What are the 3 main types of heat?

Radioactive decay, friction, and residual

Where are mafic rocks found

In the oceanic crust

Where are felsic rocks typically found

Continental crust

How are grains aligned in sedimentary rock

Grains are aligned parallelly in thin sections

Radioactivity/Radioactive decay

Produces a sufficient amount of cumulative heat in the Earth, slowing the cooling of the planet overall.

Which would have more silica content: Granite or Basalt?

Granite

Residual

Rocks being able to retain heat

Mafic Volcanoes

Forms darker rocks; non-viscous lava- lava spreads out in a thin sheet

Felsic volcanoes

Forms lighter rocks; viscous lava- lava forms in a thick, dome-lie blob

Fractional Crystallization

Process where minerals crystallize out of magma as it cools, forming layers of different mineral compositions. Helps concentrate valuable minerals.

assimilation

solid or fluid foreign material is incorporated into magma

xenolith

wall rock embedded in igneous rock

Glassy rock

happens when lava flows into water and cools almost instantly. Ex: obsidian

sills

forms horizontally

dike

forms vertically

batholith

An extremely large area of granite rock

Batholith example

Sierra Nevada

Pillow Basalt

Bulbus structures that cool from the outside instantly, creating a glass structure on the outside