Igneous Rocks

Question 1

What texture is phaneritic?

Answer 1

course cyrtsalline

Question 2

What texture is aphanitic?

Answer 2

fine grain

Question 3

What texture is pgematic?

Answer 3

big crystals, bigger than 1 cm

Question 4

What texture is vesicular?

Answer 4

has holes/vesicles

Question 5

What texture is porphyritic?

Answer 5

mix of big & small crystals

Question 6

What is an example of a mafic, vesicular rock?

Answer 6

scoria

Question 7

What is an example of a mafic, fine textured, crystalline rock?

Answer 7

basalt

Question 8

What is an example of a mafic course grain, crystalline rock?

Answer 8

Gabbro

Question 9

What is an example of a felsic, vesicular rock?

Answer 9

pumic

Question 10

What is an example of a felsic, glassy rock?

Answer 10

obsedian

Question 11

What is an example of a felsic fine grain, crystalline rock?

Answer 11

ryolite

Question 12

What is an example of a felsic, course, crystalline rock?

Answer 12

granity

Question 13

What is an example of a felsic, very course, crystalline rock?

Answer 13

pegmatite

Question 14

Does a viscous lava flow easily or not?

Answer 14

Not

Question 15

Does mafic or felsic lava flows viscous or more readily?

Answer 15

Felsic is viscous, mafic is more readily

Question 16

Describe a sill

Answer 16

Intrusive, mafic, flat/tabular shape. Concordant.

Question 17

Describe laccolith

Answer 17

Intrusive, felsic, mushroom shaped, concordant

Question 18

Describe batholith

Answer 18

Intrusive, felsic, bottom-less, large/huge scale (upside-down bathtub)

Question 19

Describe dike

Answer 19

Intrusive, mafic OR felsic, small scale, offshoots from bigger pools, discordant (cuts across layers) Can also feed a laccolith

Question 20

What do you call an intrusive lava flow that has an indescribable shape?

Answer 20

pluton

Question 21

What does andesitic mean?

Answer 21

felsic/mafic mix

Question 22

What does the Bowen rxn series tell us? What is the mineral that is the first to form?

Answer 22

What minerals crystallize @ what temperatures.

Olivine

Question 23

In the context of Bowen rxn series, what is fractionation?

Answer 23

The cooling FIRST of the outside edges (olivine first), and the mineral that forms pulls elements from the pool so that the chem composition of the pool changes slightly.

Question 24

Is the bottom or top of the Bowen rxn series more stable?

Answer 24

Bottom, which is why quartz is everywhere (like at the beach). You hardly see olivine in sedimentary rocks.

Question 25

Study Bowen's Rxn Series

Answer 25

Pew pew pew

Question 26

What is this rock?

Answer 26

Scoria

Question 27

Study this classification table

Answer 27

Ooo

Question 28

What are these two rocks and why are they similar?

Answer 28

Rhyolite (on the right) is the volcanic equivalent of granite (on the left). Both consists of light colored silicates.

Question 29

The statements that follow relate to terms describing igneous rock textures. For each statement, identify the appropriate term: a. Opening produced by escaping gas b. Obsedian exhibits this texture c. A matrix of fine crystals surrounding phenocrysts d. Crystals are too small to be seen with the naked eye e. A texture characterized by two distinctly different crystal sized. f. Course grained, with crystals of roughly equal size

Answer 29

a. vesicular b. glassy c. groundmass d. aphanitic e. porphyritic f. phaneritic

Question 30

What does a porphyritic texture indicate about igneous rock?

Answer 30

Since all minerals within a magma do not crystallize at the same rate at the same time during cooling, it is poss for some crystals to become quite large before others start to form.W

Question 31

What is the difference between magma and lava?

Answer 31

Lava is magma that has reached the surface

Question 32

An igneous rock with an aphaneritic texture was most likely intrusive. T/F

Answer 32

F

Question 33

Mafic igneous rocks are generally dark in color and relatively rich in iron and magnesium. T/F

Answer 33

T

Question 34

A mafic, flat, tabular, concordant igneous intrusion is called: A) batholith B) laccolith C) Sill D) Dike E) none of the above

Answer 34

C) Sill