Magma and Lava

Question 1

molten rock material generated by partial melting in the earth’s crust

Answer 1

magma

Question 2

magma that rises and erupts onto the surface of the earth

Answer 2

lava

Question 3

liquid portion of the magma

Answer 3

melt

Question 4

gaseous portion of the magma

Answer 4

volatiles

Question 5

solid portion of the magma

Answer 5

crystals

Question 6

magma will move to areas with _ pressure

Answer 6

less

Question 7

magma moves _

Answer 7

upward

Question 8

magma is naturally _ than the surrounding rock

Answer 8

less dense

Question 9

depending on its composition and temperature, magma _

Answer 9

evolves

Question 10

gases in magma tend to be _ in the melt portion at depth due to high _

Answer 10

dissolved; pressures

Question 11

as SiO2 becomes concentrated, magma becomes more

Answer 11

viscous

Question 12

the process where magma and lava loses its heat and solidifies

Answer 12

crystallization

Question 13

rocks that formed as a result if crytallization

Answer 13

igneous rocks

Question 14

igneous rocks that formed beneath the earth’s surface

Answer 14

plutonic/intrusive igneous rocks

Question 15

igneous rocks that solidified at the earth’s surface

Answer 15

volcanic/extrusive igneous rocks

Question 16

will tend to have larger crystal sizes

Answer 16

intrusive igneous rocks

Question 17

will tend to have smaller crystal sizes

Answer 17

extrusive igneous rocks

Question 18

the process where pre-existing rock is heated to the point of partially melting

Answer 18

partial melting

Question 19

partial melting within the earth’s crust

Answer 19

anatexis

Question 20

factors determining the type of magma

Answer 20

1. composition, temperature, and depth of source rock
2. % partial melting of source rock
3. source rock’s previous melting history
4. diversification processes after partial melting

Question 21

3 origins of magma

Answer 21

1. temperature increase
2. decompression melting
3. addition of volatiles

Question 22

magma is generated through heat transfer from a hot body until the melting point of the minerals present is reached

Answer 22

temperature increase

Question 23

the increase of temperature with depth

Answer 23

geothermal gradient

Question 24

the result of a decrease in pressure in the system

Answer 24

decompression/adiabatic melting

Question 25

agents that reduce the melting point of rocks

Answer 25

flux

Question 26

the presence of flux weakening the bonds between atoms, making it melt

Answer 26

addition of volatiles

Question 27

crystallization along the walls of a magma chamber and crystals preferentially form and adhere to the edges

Answer 27

marginal accretion

Question 28

fractionation processes that occur when crystals develop with significantly different densities than the magma

Answer 28

gravitational separation

Question 29

dense minerals sink and accumulate at the bottom of the magma body

Answer 29

crystal settling

Question 30

light minerals float and accumulate at the top of the magma body

Answer 30

crystal flotation

Question 31

magma body is subjected to stress, squeezing out the melt and leaving behind crystals

Answer 31

filter pressing

Question 32

liquids and crystals are segregated due to velocity, density, and temperature

Answer 32

convective flow segregation

Question 33

two or more dissimilar magmas coexist but retain their distinctive characteristics

Answer 33

magma mingling

Question 34

mixing of two or more magmas, with their individual characteristics no longer recognizable

Answer 34

magma mixing

Question 35

development of more than one type of igneous rock from a parent magma

Answer 35

magmatic differentiation

Question 36

the incorporation and digestion of foreign material into the magma body

Answer 36

magmatic assimilation

Question 37

inclusions in magmatic bodies

Answer 37

xenolith

Question 38

a body of magma

Answer 38

pluton

Question 39

rocks that break away from the surrounding rock and assimilate into the pluton

Answer 39

stopes

Question 40

one parent magma produces two distinct daughter magma

Answer 40

liquid fractionation

Question 41

selective diffusion of ions in the magma due to compositional, thermal, or density gradients

Answer 41

differential diffusion

Question 42

separation of magma into two or more liquid phases

Answer 42

liquid immiscibility/liquid-liquid fractionation

Question 43

genetically related magmas that evolved from a parent magma

Answer 43

magma series/magma suite

Question 44

decrease in Fe and Mg with increasing silica and alkali concentrations

Answer 44

calc-alkaline magma

Question 45

where do calc-alkaline magmas occur

Answer 45

convergent margin environments with volcanic arcs and subduction zones

Question 46

enrichment in Fe, low to moderate SiO2 concentrations, depleted MgO and CaO

Answer 46

tholeiitic magma

Question 47

where do tholeiitic magmas occur?

Answer 47

extensional environments such as ocean ridges and continental rifts. also in intraplate settings with immature arcs and volcanic arc crusts

Question 48

highly enriched in Na2O and/or K2O and contains extremely diverse SiO2 contents

Answer 48

alkaline magmas

Question 49

high concentration of silicic and basic rocks, with little intermediate rocks

Answer 49

bimodal magma

Question 50

bimodal magma suites

Answer 50

basic from mantle; silicic from crust

Question 51

bivariate diagrams showing the relative relationship of oxide compounds

Answer 51

Harker Diagrams

Question 52

as silica increases in a harker diagram

Answer 52

K2O and Na2O also increase

Question 53

most abundant element in the earth’s crust

Answer 53

OSAICSPM

Question 54

5 types of magma

Answer 54

1. ultramafic 2. mafic 3. intermediate 4. dacitic 5. felsic

Question 55

magma that is <45% SiO2, >1,200°C, very fluid, very low gas content

Answer 55

ultramafic magma

Question 56

magma that is 45-52% SiO2, 1,200-1,000°C, fluid, low gas content

Answer 56

mafic magma

Question 57

magma that is 52-63% SiO2, 1,000-800°C, intermediate viscosity and gas content

Answer 57

intermediate magma

Question 58

magma that is 63-68% SiO2

Answer 58

dacitic magma

Question 59

magma that is 68-77% SiO2, 800°C-600°C, highly viscous, very gaseous

Answer 59

felsic magma