Igneous Petrology (Part 1 - Magmatic Processes, Magma Series, Types of Magma) Flashcards
Lava and Magma, Magmatic Processes, Magma Series, Types of Magma
The sub-branch of Petrology that primarily focuses on processes and rocks that are formed from magma and lava.
Igneous Petrology
Molten rock material generated by partial melting of Earth’s mantle and crust.
Magma
Magma that rises and erupts onto the surface of Earth.
Lava
The liquid portion of the magma.
Melt
The gaseous portion of the magma
Volatiles
The solid portion of the magma
Crystals
Magma will move towards areas with what pressures
Less pressure
What does more undissolved gases mean in magma?
Greater volume = More explosive
More fluid magma tends to contain what content?
less SiO2 content
What does greater SiO2 concentration mean?
More viscous = More explosive
The processes were the magma or lava looses its heat and crystallizes
Crystallization
Rocks that formed as a result of crystallization of magma or lava.
Igneous Rocks
Igneous rocks that formed beneath the surface as a result of loosing mobility.
Plutonic Rocks
Will tend to have larger crystal sizes as they have time to grow.
Intrusive Igneous Rock
Igneous rocks that solidified at the surface as a result of extrusion.
Volcanic Rocks
Will tend to have smaller crystal sizes as they rapidly cool and crystallize from the cooler environment.
Extrusive Igneous Rock
The process where your pre-existing rock is heated to the point of partially melting.
Partial Melting
The partial melting within the Earth’s crust.
Anatexis
What are the factors that determine the types of magma?
- Composition, temperature and depth of the source rock.
- Percent partial melting of the source.
- Source rock’s previous melting history.
- Diversification processes
Origins of Magma
Temperature increase
Decompression melting
Addition of volatiles
Increase of temperature with depth
Geothermal gradient
Occurs as a result of decrease in pressure in the system. (Also known as adiabatic melting)
Decompression melting
Agents that reduces melting temperature of a substance.
Flux
Occurs when crystallization along the walls of the magma chamber in which crystals preferentially form and adhere to the edges.
Marginal Accretion
Includes fractionation processes that occur when crystals develop with significantly different densities than the surrounding magma.
Gravitational separation
A process during fractional crystallization where the first dense minerals that mineralize sink and accumulate at the bottom of the magma body.
Crystal Setting
A process during fractional crystallization where the first lighter minerals that mineralize float and accumulate at the top of the magma body.
Crystal Flotation
A process during magma cooling that occurs when the magma bod is subjected to stress.
Filter pressing
Occurs whereby liquids and crystal are segregated due to factors such as velocity, density or temperature.
Convective Flow Segregation
Two or more dissimilar magmas coexist but retaining their distinctive characteristics.
Magma Mingling
Thorough mixing of two or more magmas, with the individual characteristics no longer recognizable.
Magma Mixing
Development of more than one type of igneous rock in situ from a common magma.
Magmatic Differentiation
The incorporation and digestion of solid or fluid foreign materials, such as the wall rock
Magmatic Assimilation
Inclusions in magmatic bodies.
Xenolith
One parent magma fractionates to produce two or more distinctly different daughter magmas with different compositions
Liquid Fractionation
Involves the selective diffusion of ions in the magma due to compositional, thermal or density gradients.
Differential Diffusion
Also called liquid-liquid fractionation, the separation of magma into two or more distinct immiscible liquid phases.
Liquid Immiscibility
Consists of genetically-related magmas with a composition that evolved from a common, original, parental magma.
Magma Series
Record a progressive decrease in iron and magnesium with increasing SiO2 and alkali concentrations.
Calc-alkaline magmas
What rocks produce in calc-alkaline
Andesites, Dacites, Rhyolites, Basalts
Experience enrichment in iron at low to moderate SiO2 concentrations with increasing fractionation due to depleted MgO and CaO from early crystallization of forsterite olivine and Ca-plagioclase.
Tholeiitic magmas
What rocks produce in tholeiitic magmas
Large volumes of basalt
Magmas that are less common than calc-alkaline or tholeiitic magmas, highly enriched in Na2O and/or K2O
Alkaline magmas
Characterized by high concentrations of silicic and basic rocks, with little intermediate rocks
Bimodal magma suites
A graphical method used to discriminate samples through their chemical content into correctly identifying an igneous rock.
Variation Diagrams
Bivariate diagrams showing the relative content relationship of oxide compounds with SiO2 as the magma evolves.
Harker Diagrams
With increasing silica, what trends follow
- Decrease in TiO2, FeO, MgO, CaO and P2O5
- Increase in K2O and Na2O
- No strong variation in Al2O3.
8 most abundant elements in the continental crust
Oxygen
Silicon
Aluminum
Iron
Calcium
Sodium
Potassium
Magnesium
Explain the types of Magma from Ultramafic to Felsic
yes
Explain Bowen’s Reaction Series
letsgo kaya mo yan
Igneous rocks that are dominantly composed of dark-colored silicates but can commonly appear green, enriched in olivine, pyroxene and plagioclase.
Ultramafic
What rocks form in Ultramafic
Peridotite and Komatiite
Why is komatiite extinct again?
aba malay ko (joke) ano raw temp pressure NOT FAVORABLE!!!! Ultramatic but volcanic (no ultramafic lava exist) tsaka ano kasi hindi na favorable ang setting sa earth ngaun frfr
Igneous rocks that are dominantly composed of dark-colored silicates such as pyroxenes, plagioclase and amphiboles.
Mafic
Mafic is also called?
Basaltic
mafic magma may form what rocks depending on its texture.
Gabbro or Basalt
Igneous rocks that are gray-colored to salt-and-pepper, depending on the size of the mineral grains.
Intermediate
Intermediate is also called?
Andesitic
What rocks would form depending on its texture in Intermediate?
Diorite or Andesite
Igneous rocks that are dominantly composed of light-colored silicates such as quartz and feldspars.
Felsic
Felsic is also called?
Granitic
What rocks would form in felsic, depending on its texture?
Granite or Rhyolite
