Chapter 3- Igneous Flashcards
What is the definition of an igneous rock?
An igneous rock is a type of rock formed through the cooling and solidification of magma or lava.
True or False: Igneous rocks are classified based on their mineral composition and texture.
True
Fill in the blank: Igneous rocks that cool and solidify below the Earth’s surface are called ________ rocks.
Intrusive
What is the main difference between intrusive and extrusive igneous rocks?
Intrusive rocks cool slowly beneath the Earth’s surface, while extrusive rocks cool quickly on the surface.
What is the most common extrusive igneous rock?
Basalt
What is the most common intrusive igneous rock?
Granite
Fill in the blank: Igneous rocks are often used in ________ and ________ construction due to their durability.
monument; building
What is the term for the process of magma cooling and crystallizing to form igneous rocks?
Solidification
True or False: Igneous rocks can be formed from both magma and lava.
True
What is the term for the size, shape, and arrangement of mineral grains in an igneous rock?
Texture
Fill in the blank: Igneous rocks that are formed from the cooling and solidification of lava are called ________ rocks.
Extrusive
What is the term for the process of magma rising and cooling beneath the Earth’s surface?
Intrusion
True or False: Basalt is a common extrusive igneous rock with a fine-grained texture.
True
What is the term for the process of magma mixing with other rocks and changing composition?
Magma mingling
Fill in the blank: Igneous rocks are often classified based on their ________ and ________ composition.
mineral; chemical
What is the term for the process of magma cooling and forming crystals within the Earth’s crust?
Crystallization
True or False: Pumice is an example of an extrusive igneous rock with a vesicular texture.
True
What is the term for the process of magma cooling and forming crystals at the Earth’s surface?
Volcanism
Fill in the blank: Igneous rocks that contain a high percentage of quartz are classified as ________ rocks.
Felsic
What is the term for the process of magma cooling and forming crystals after eruption?
Post-eruption crystallization
True or False: Diorite is an example of an intrusive igneous rock with a medium-grained texture.
True
What is the term for the process of magma cooling and forming crystals before eruption?
Pre-eruption crystallization
Fill in the blank: Igneous rocks that are rich in iron and magnesium are classified as ________ rocks.
Mafic
What is the term for the process of magma cooling and forming crystals within a volcano?
Intravolcanic crystallization
Pegmatitic
Extremely course grained (usually under >5 cm), forms when magma cools very slowly
Porphyritic
Includes 2 distinct crystal sizes, with the larger Phenocrysts having formed first during slow cooling underground and the smaller ground mass forming during more rapid cooling at the Earth’s surface.
Phenocrysts
large crystals that form early in the crystallization of magma and are embedded in a finer-grained matrix in igneous rocks.
Glassy texture
Contains no crystals at all and is formed by extremely rapid cooling of the magma.
Vesicular
Contains cavities (vesicles) in extrusive rocks resulting from gas bubbles that were in the lava. Scoria and pumice are examples.
Pyroclastic texture
Consolidated pyroclastic debris such as ash, pumice or crystalline rock. Tuff and Volcanic Breccia are examples.
Intermediate rock
Silica contents between 55% and 65% by weight. Diorite and Andesite are examples.
Ultramafic rocks
<45% silica and composed almost entirely of dark-colored (black/green) ferromagnetic minerals. Peridotite and Komatite.
Differentiation
Process by which different ingredients separate from an originally homogenous mixture.
Crystal setting
Changes magma comp as the crystals are removed from the melt as they settle downwards
Partial melting
Process by which the magma composition varies as different minerals/rocks melt at different temperatures.
Assimilation
Process whereby a hot magma comp will change as it melts and assimilate adjacent rocks into the magma.
Volcanic neck
Shallow intrusion formed when magma solidifies in throat of volcano.
Dike
Shallow tabular intrusive structure that cuts across any layering in country rock (web)
Sill
Shallow, tabular intrusive structure that parallels layering in country rock. (Lines)
Sill
Shallow, tabular intrusive structure that parallels layering in country rock. (Lines)
Plutons
Deep, large, blob-shaped intrusive bosy formed of coarse grained igneous rock, commonly granitic in composition.
Stocks
Batholiths
Small plutons
Large plutons
