igneous composition

Question 1

andesitic composition has a composition btw __ and __
aka

Answer 1

comp btw granitic and basaltic
intermediate comp

Question 2

andesitic composition includes what type of minerals? What are 2 rocks under this category?

Answer 2

25% dark and rest light
fine: andesitic
coarse: diorite

Question 3

What are ultramafic igneous rocks? what part of the interior do they constitute?

Answer 3

mainly composed of dark silicates (rare at earth’s surface)
upper mantle

Question 4

Texture

Answer 4

size, shape, and arrangement of mineral grains

Question 5

Fine grained texture is common in rocks that form…

Answer 5

as small landmasses in upper crust or cool rapidly at surface

Question 6

Define fine grained

Answer 6

crystals too small for individual minerals to be identified

Question 7

Coarse-grained come from rocks, definition

Answer 7

that crystallize at great depth
mineral grains that are large enough to be identified without microscope

Question 8

Porphyritic texture

Answer 8

when molten rock containing large crystal erupts, remaining lava cools to form smaller crystals (matrix)

Question 9

what are the large crystals of porphyritic rocks called? large?

Answer 9

phenocrysts
groundmass

Question 10

Vesicular texture

Answer 10

extrusive rock with voids left by gas bubbles that escape as lava solidifies and cooling occurs rapidly to preserve it

Question 11

examples of rocks with vesicular texture

Answer 11

scoria and pumice

Question 12

Glassy texture

Answer 12

rock ejected into atmosphere by volcanic eruption and instant cooling turns it into a solid (glass)

Question 13

example of rock with glassy texture, what kind of magma do glassy textures form from

Answer 13

obsidian
silica-rich

Question 14

pyroclastic texture aka

Answer 14

fragmental
consolidation of fragments ejected by volcanic eruptions

Question 15

ex of pyroclastic texture rock and their comp

Answer 15

welded tuff (granitic) and breccia (andesitic)

Question 16

what are the two things we use to identify igneous rocks?

Answer 16

comp and texture

Question 17

what is the texture of an igneous rock a result of? comp?

Answer 17

texture: cooling history
comp: chemical makeup of parent magma and env.

Question 18

what texture does granite have?

Answer 18

coarse grained or porphyritic

Question 19

rhyolite (texture, comp) similarity to granite color, what does it indicate about its cooling, what does if often contain within it

Answer 19

fine-grained, granitic/felsic, extrusive equivalent of granite but made of light colored silicates (pinkish), glass fragments and voids, fast cooling

Question 20

obsidian (comp, silica content)
used for…

Answer 20

granitic/felsic (comp similar to light colored rocks)
high in Si
arrowheads

Question 21

pumice (comp, texture) distinct feature, color

Answer 21

granitic/felsic
glassy
often float in water
white

Question 22

Granitic dominant mineral

Answer 22

quartz, potassium feldspar

Question 23

andesite (texture, comp)

Answer 23

fine-grained, andesitic or porphyritic

Question 24

andesitic dominant mineral

Answer 24

amphibole, plagioclase feldspar

Question 24

mafic dominant mineral

Answer 24

pyroxene, plagioclase feldspar

Question 25

ultramafic dominant mineral

Answer 25

olivine, pyroxene

Question 26

diorite (texture, comp) relationship with andesite
color

Answer 26

coarse-grained, andesitic
extrusive equivalent of andesite

Question 27

basalt (comp, texture)

Answer 27

mafic
fine-grained/porphyritic

Question 28

what is the most common extrusive igneous rock
what does it make up

Answer 28

basalt
upper layers of o.crust

Question 29

gabbro (comp, texture)
relationship with basalt, makes up….

Answer 29

mafic
coarse-grained
intrusive equivalent, significant portion of o.c

Question 30

scoria comp texture color

Answer 30

mafic/basaltic
vesicular
red

Question 31

breccia (comp, texture)

Answer 31

mafic/basaltic
pyroclastic (larger fragments)

Question 32

peridotite (comp, texture)

Answer 32

ultramafic
coarse-grained

Question 33

TF: Different rock types can be generated from the same melt

Answer 33

true

Question 34

crystallization begins dark silicates vs light

Answer 34

dark: high temp
light: lower temp

Question 35

what is the order of minerals that crystallize first to last

Answer 35

olivine, pyroxene, plagioclase feldspar, amphibole, biotite, muscovite potassium feldspar, quartz

Question 36

Why would it be unlikely to find olivine and quartz in one igneous rock?

Answer 36

quartz crystallizes at lower temp than olivine (olivine first to cool, quartz is the last)

quartz has lots of silica and low in iron and mg, which are the elements consisting of olivine

Question 37

minerals that form in the same range in bowen’s reaction series are found

Answer 37

together in the same igneous rock

Question 38

magmatic differentiation

Answer 38

formation of one or more secondary magmas from a single parent magma

certain elements are selectively removed to create a more felsic or basaltic rock

Question 39

what is a mechanism of magmatic differentation

Answer 39

crystal settling: dense materials sink to bottom of magma chamber and lower and upper parts of chamber will have rocks of dif. como