L1: Intro to and the classification of Ig Rocks Flashcards

1
Q

igneous petrology: definition

A

study of magmas and the minerals that crystallize from them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does this tool for classification include?

Texture/fabric of rock

A

field relations, hand specimen, and thin section

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does this tool for classification include?

Mineralogical

A

the mineral species present & their composition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does this tool for classification include?

Modal Abundance

A

the measured/estimated volumetric proportions of minerals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does this tool for classification include?

Chemical Composition

A

major oxide components (>0.1%) & the recalculated mineral mode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

definition of this texture

Phaneritic

A

all crystals are visible to the naked eye (>1mm)

indicates slow cooling; intrusive and plutonic rocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

definition of this texture

Aphanitic

A

all crystals are too small to be visible to the naked eye

rapid cooling; extrusive and volcanic rocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

definition of this texture

Porphyritic

A

2 dominant grain sizes: the large phenocrysts and finer-grained groundmass

suggests multi-stage cooling history

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

equigranular

A

uniform grain sizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

definition of feldspathoids

A

Si-poor minerals similar to feldspars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

examples of “foids”

A

Leucite, Nepheline, Sodalite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What rocks plot near P on QAPF?

A

anorthosite, gabbro, diorite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

volcanic QAPF

A

aphanitic/glassy; (>10% crystals); ignores groundmass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Best method for classifying aphanitic/glassy rocks?

A

chemical composition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly