Exam 1

Question 1

Petrology

Answer 1

Study of rocks using optical microscopy

Question 2

Reasons why we study petrology

Answer 2

1. Crust and mantle are igneous
2. Most metallics ores are associated w/ igneous rocks and process
3. Natural hazards
4. All of terrestrial planets/moons have igneous crust

Question 3

Exposed

Answer 3

1. Volcanic: by volcanic eruptions
2. Intrusive: exposed by uplift, erosion, glaciation
   -intrusive igneous rocks are usually older than other formations

Question 4

Melting

Answer 4

1. Isothermal decomposition
2. Add h20
3. Add heat

Question 5

Three broad environments

Answer 5

1. Extrusive (volcanic)
2. Intrusive (plutonic)
3. Hypobyssal (shallow intrusive rocks )

Question 6

Congruent melting

Answer 6

Melt w/ same composition as the source( melting 100%- liquid) usually never happens

Question 7

Systems 1,2,3

Answer 7

1. Open- transfer heat and matter across the boundary between the system and the surroundings
2. Closed - transfer of heat m/y
3. Isolated- no transfer of heat or matter ( not possible)

Question 8

OIB

Answer 8

Ocean island basalt (alkali olivine basalt)

Question 9

MORB

Answer 9

Mid ocean ridge basalt (tholeiite)

Question 10

IAT

Answer 10

Island arc thoeliite

Question 11

WPB

Answer 11

Within plate basalts (continental rift -highly alkaline )

Question 12

Primary basalt vs. primitive basalt

Answer 12

Primary basalt: first formed (usually don’t erupt )
Primitive: most mafic that are erupted

Question 13

Xenolith types

Answer 13

1. Eucrites (gabbro): ca plag, augite, olivine
2. Dunite and wehrlite: contain different proportion of mg rich olivine and diopside pyroxenes
3. Lherzolites and harzburgites: mg olivine, diopside, mg rich orthopyrozene
4. Garnet peridotite and elcogite: ca rich and ca poor pyroxene, olivine and rich garnet

Question 14

Hasashi kono

Answer 14

-Believed tholeittic lavas- contain on,y 1 group xenoliths
-mildly alkaline basalts: groups 1 and 2 xenos
-Highly alkali basalts: group 1,2,3 xenos
-stronglyy si deficient basalt: group 1,2,3,4 xenos

Question 15

I-type

Answer 15

Igneous source
- trondhjenite

Question 16

S-type

Answer 16

Sedimentary source
- Granite

Question 17

A-type

Answer 17

An orgenic , Alkalin
(Continental rifting)

Question 18

M type

Answer 18

charnocite (metamorphic rocks)

Question 19

Granite tends to be paraluminous

Answer 19

(Has alot of Alumnous ) S-type

Question 20

Metaluminous

Answer 20

Biotite
hornblende
(pyroxene)

Question 21

Peraluminous

Answer 21

Biotite
muscovite
garnet
cordierite
andaluite
Spinel

Question 22

Peralkaline

Answer 22

annite-rich
biotite
Fe-rich amphibole
(arfredsonite, riebeckite, eg.)
fayalite

Question 23

Melting (anatexis)

Answer 23

1. Addition of h2o
2. Decompression
3. Heating

Question 24

What is an Invariant in a one-component system?

Answer 24

Whenever three places coexist at equilibrium.

Question 25

What does Univariant mean?

Answer 25

A state where a system is in balance.

Question 26

What does Disequilibrium refer to?

Answer 26

Not in balance / not at rest.

Question 27

What is MoHo?

Answer 27

The boundary between the crust and lithosphere mantle in the upper mantle.

Question 28

What is the low velocity layer?

Answer 28

The area between the lithosphere mantle and asthenosphere mantle.

Question 29

What is the transition zone?

Answer 29

The area between two discontinuities. 400 km and 670 km

Question 30

What is a Discontinuity?

Answer 30

polymorphic mineral transformations and/or collapse of mineral structures.

Question 31

What is the Solidus?

Answer 31

The lower curve indicating no liquid.

Question 32

What is the Liquidus?

Answer 32

The upper curve specifying the composition of any liquid that coexists with a solid at a particular temperature.

Question 33

What is the Solvus?

Answer 33

The limit at which solid solutions remain stable.

Question 34

What is a Eutectic?

Answer 34

the lowest temp at which liquid phase is stable at a given pressure

Question 35

What are Igneous rocks?

Answer 35

Any crystallization or glassy rock (including ash) that forms directly.

Question 36

What is a System in geology?

Answer 36

Any part of the universe under study.

Question 37

What is a Phase?

Answer 37

Any part of a system that is mechanically separable and can be studied: solid, liquid, gas.

Question 38

What are Components in a system?

Answer 38

The least number of chemical species that fully describe the system.

Question 39

Who is Misashi Kono?

Answer 39

A Japanese geologist who studies the petrology of volcanic rocks.

Question 40

What are tholeiitic lavas?

Answer 40

Lavas that contain only one group of phenocrysts.

Question 41

What are mildly alkaline basalts?

Answer 41

Basalts that contain groups 1 and 2 xenoliths.

Question 42

What are highly alkaline basalts?

Answer 42

Basalts that contain groups 1, 2, and 3 xenoliths.

Question 43

What are strongly Si-deficient basalts?

Answer 43

Basalts that contain groups 1 and 4 xenoliths.

Question 44

What are Gabbros?

Answer 44

Rocks that include woeful, Ca-Plag, Augite, and Olivine.

Question 45

What are Dunite and Wehrlite?

Answer 45

Rocks with different properties of Mg-Olivine and diopsidic clinopyroxene.

Question 46

What is the Al-bearing phase in some rocks?

Answer 46

Plagioclase or spinel.

Question 47

What are Harzburgite and Lherzolite?

Answer 47

Rocks containing Diopside, Mg-rich olivine, Mg orthopyroxene (enstatite), and spinel.

Question 48

What is Garnet peridotite/eclogite?

Answer 48

Rocks that contain Ca-rich pyroxene, olivine, and pyrope garnet.

Question 49

Olivine group

Answer 49

Forsterite and fayalite

Question 50

garnet group

Answer 50

Almandine, pyrope, grossular, spessertine

Question 51

Amphibolite group

Answer 51

Hornblende, plagioclase

Question 52

Feldspar group

Answer 52

Plagioclase, alkali, potassium