chapter 3 igneous and intrinsic activity

Question 1

____ produced of entirely igneous rocks

Answer 1

mantle

Question 2

____ : parent material for igneous rocks

Answer 2

magma

Question 3

magma component: composed of the earth most common components

Answer 3

liquid- “melt”

Question 4

magma component: possibly absent: crystal and silicates

Answer 4

solid

Question 5

magma component: volatiles- vaporize at surface pressures- H20, Co2, So2

Answer 5

Gas

Question 6

as temperature increases magma becomes ________, if it continues to increase bonds _____ and rock ______

Answer 6

crystaline rock, become destroyed, melts

Question 7

Cooling reverses the events of melting. liquid melt —> organised solid structure

Answer 7

crystalization

Question 8

Chem comp, # of volatiles, rate of colling

Answer 8

How magmas differ

Question 9

when magma solidifies it creates ___ rocks

Answer 9

Intrusive igneous

Question 10

lava cools in surface creating ____ rocks

Answer 10

extrusive igneous

Question 11

Texture and crystal visibility of intrusive igneous rocks

Answer 11

course-grained + visible crystals

Question 12

Texture and crystal visibility of extrusive igneous rocks

Answer 12

fine-grained + volcanic debris

Question 13

Feldspar and quartz dominant rocks

Answer 13

felsic rocks

Question 14

category of igneous rocks with around 10% dark silicate minerals (usually biotite or amphisole)

Answer 14

felsic rocks

Question 15

category of igneous rocks that are the major constituants of the earths crust

Answer 15

felsic rocks

Question 16

Category of igneous rock that has at least 25% dark silicates (usually amphibole, pyroxene, and biotite mica or plagioclase feldspar

Answer 16

Andesetic (intermediate)

Question 17

Category of igneous rock that contain dark silicate minerals and plagiocase feldspar

Answer 17

Mafic

Question 18

Category of igneous rock that typically darker and denser than granitic rock

Answer 18

Mafic

Question 19

category of igneous rock that has many dark silicates (usually olivine and pyroxene) ex. peridiodite

Answer 19

ULTRAMAFIC

Question 20

Granitic Magma has _____ therefore is thicker

Answer 20

more silicates

Question 21

Basaltic Magma has _____ therefore is smoother

Answer 21

less silicates

Question 22

Texture of igneous rock as a result of very rapid cooling ex. Pumis (ash)

Answer 22

Glassy

Question 23

Texture of igneous rock as a result of being debris of eruption, with fine fragments of glass instead of interlocking crystals

Answer 23

pyroclastic

Question 24

Texture of igneous rock as a result of lava cooling quickly (fine-grained)

Answer 24

Aphanatic

Question 25

Texture of igneous rock where the rate of cooling starts slow then speeds up, classified by the observation of large crystals surrounded by small crystals

Answer 25

poryphyritic

Question 26

Texture of igneous rock classified by the presence of large interlocking crystals surrounded by small crystals. The small crystals are called _____

Answer 26

pegmatatic, groundmass

Question 27

Texture of igneous rock classified by the creation from the cooling of magma at depth (coarse-grained)

Answer 27

Phaneric

Question 28

Rock that is phanaretic and felsic

Answer 28

Granite

Question 29

Rock that is phaneretic and intermediate

Answer 29

Diorite

Question 30

Rock that is phaneretic and mafic

Answer 30

Gabbro

Question 31

Rock that is Aphanatic and felsic

Answer 31

Rhyolite

Question 32

Rock that is Aphanatic and intermediate

Answer 32

Andesite

Question 33

Rock that is Aphanatic and Mafic

Answer 33

Basalt

Question 34

Rock that is Poryphitic and Felsic

Answer 34

Granite porphyry

Question 35

Rock that is Poryphitic and intermediate

Answer 35

Andesite porphyry

Question 36

Rock that is Poryphitic and Mafic

Answer 36

Basalt Porphyry

Question 37

Most magma originates when essentially solid rock, located in the crust and upper mantle, _____

Answer 37

melts

Question 38

This increase in temperature with depth, known as the _____

Answer 38

geothermal gradient

Question 39

Melting, which is accompanied by an increase in volume, occurs at higher temperatures at depth because of ________

Answer 39

greater confining pressure

Question 40

Conversely, reducing confining pressure _______

Answer 40

lowers a rock’s melting temperature

Question 41

when confining pressure drops sufficiently __________

Answer 41

decompression melting is triggered

Question 42

Decompression melting occurs where hot, solid mantle rock ______

Answer 42

ascends in zones of convective upwelling

Question 43

As an oceanic plate sinks __________

Answer 43

both heat and pressure drive water from the subducting crustal rocks

Question 44

Melting of peridotite generates _____ magma

Answer 44

basaltic

Question 45

In summary, magma can be generated three ways:

Answer 45

(1) when an increase in temperature causes a rock to exceed its melting point; (2) in zones of upwelling a decrease in pressure (without the addition of heat) can result in decompression melting; and (3) the introduction of volatiles (principally water) can lower the melting temperature of hot mantle rock sufficiently to generate magma

Question 46

basaltic magma crystallizes over a range of at least ____

Answer 46

200 °C of cooling

Question 47

______ process occurs when the earlier-formed minerals are more dense (heavier) than the liquid portion and sink toward the bot- tom of the magma chamber

Answer 47

crystal settling

Question 48

The formation of one or more secondary magmas from a single parent magma is called _______

Answer 48

magmatic differentiation

Question 49

Once a magma body forms its composition can also change through the incorporation of foreign material. For example, as magma migrates through the crust, it may incorporate some of the surrounding host rock, a process called ________

Answer 49

assimilation

Question 50

This process occurs when one magma body intrudes another that has a different composition

Answer 50

magma mixing

Question 51

he incomplete melting of rocks is known as ________, a process that produces most magma

Answer 51

partial melting

Question 52

When magma rises through the crust, it forcefully displaces preexisting crustal rocks referred to _________

Answer 52

as host or country rock.

Question 53

The structures that result from the emplacement of magma into preexisting rocks are called ________

Answer 53

intrusions or plutons

Question 54

Igneous bodies are said to be ________ if they cut across existing structures

Answer 54

discordant

Question 55

Igneous bodies are said to be ________ if they form poarallel to features such as sedimentary strata

Answer 55

concordant

Question 56

_____ are discordant bodies that cut across bedding surfaces or other structures in the host rock.

Answer 56

dikes

Question 57

_____ are nearly horizontal, concordant bodies that form when magma exploits weak- nesses between sedimentary beds

Answer 57

sills

Question 58

________ form as igneous rocks cool and develop shrinkage fractures that produce elongated, pillar-like columns.

Answer 58

Columnar joints

Question 59

By far the largest intrusive igneous bodies are _______

Answer 59

batholiths

Question 60

When molten material is quenched instantly, a mass of unordered atoms, referred to as ____, forms

Answer 60

glass

Question 61

Rocks of intermediate compsition, (e.g., andesite and diorite) are rich in plagioclase ______

Answer 61

feldspar and amphibole

Question 62

“Strange rock” - Rock embedded in a seperate matrix

Answer 62

xenolith

Question 63

Melting mechanisms - Mid Ocean Ridge

Answer 63

- Hot material is brought to the surface

Question 64

Melting mechanisms -Hotspot (mantle plume)

Answer 64

Adds heat to the base of the lithosphere

Question 65

Melting mechanisms -Subduction zone

Answer 65

A subducting plate brings water with it, thereby decreasing the melting point of the other plate