GEOLOGY 12
CHAPTER 3 WORKSHEET
IGNEOUS ROCKS AND PROCESSES
Name __________________
Part A The Rock Cycle
1.
A ______________ consists of many individual mineral grains firmly held together in a solid, cohesive
mass.
2.
A rock with lots of void space within or between mineral grains would have good __________________.
3.
If the pores or cracks within a rock are interconnected, the rock has good _________________________.
4.
Force applied to an object is termed stress; deformation that results from stress is called _____________.
5.
If stress on a material exceeds its __________________ _________________, the material will undergo
some sort of permanent deformation.
6.
Rocks which crystallize from hot silicate melts are called ___________________ rocks.
7.
The idea that rocks are continually subject to change over long periods of geologic time is the essence of
the _______________ _______________.
8.
Which situation below describes rocks that would have good porosity and good permeability?
a.
b.
c.
d.
9.
Which phrase below best defines the situation when rocks are being subjected to forces that are squeezing
them?
a.
b.
c.
d.
10.
rocks that consist of tightly packed interlocking crystals
rocks that have finer materials filling gaps between larger grains
rocks that consist of well-rounded grains of about the same size
rocks that consist of platy mineral grains, like clay minerals
rocks are undergoing compressive stress
rocks are subjected to plastic strain
rocks are undergoing tensile stress
rocks are showing elastic strain
In your own words, describe the processes involved and the rocks formed during the rock cycle.
(Use correct terminology but do not include shortcuts.)
Part B Igneous Rocks (Fill In The Blank)
1.
Rocks which crystallize from magmas are called ____________________ rocks. Those cooled
slowly below the surface of the crust have a ______________-grained texture and are called
____________________ or _____________________.
2.
If the magma reaches the surface of the Earth it is called _____________ and the rocks, which cool
relatively quickly, have a ______________-grained texture and are called ____________________ or
_____________________.
3.
When lava cools so rapidly that no crystals form the rocks will have a ________________ texture.
4.
The majority of magmas are formed in the _____________ _______________, at depths between 50-250
kilometers.
5.
If pressure is lessened on rocks at great temperatures, the rocks may begin to ___________.
6.
Dissolved water and various gases found in magmas are called ___________________.
7.
The effect of increased volatiles in a magma is to __________________ the melting temperatures.
8.
The melting temperature of a mixture of minerals is always ________________ than the melting
temperatures of the individual minerals.
9.
_________________ diagrams plot temperature against composition for a given pressure.
10. Local sources of heat within the crust or mantle include concentrations of radioactive elements, and
_____________________ caused by plate motions.
11. According to Bowen's Reaction Series, the first minerals to crystallize from a silicate magma will be
relatively __________ in silica.
12. The continuous reaction series applies to the ___________________ ______________ minerals.
13. The discontinuous reaction series applies to the __________________________ minerals.
14. A magma that is rich in magnesium and iron and relatively poor in silica is called _____________.
15. In the process of ______________________ _______________________, early formed crystals may
settle out of the magma, thus changing the composition of the remaining melt.
16. The process by which a magma incorporates the rock around it is called __________________________.
17. In magma mixing, two or more magmas combine to produce a hybrid melt intermediate in mineral
_________________________.
18. A ___________________ basalt would contain bubbles or holes where gases were trapped as the magma
cooled.
19. In a porphyritic rock, a finer groundmass or matrix surrounds the larger-sized ______________________.
20. A plutonic rock which consists almost completely of olivine and pyroxene would be described as
________________________.
21. The most common volcanic rock, which makes up the seafloor, is __________________.
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22. Geologists use ___________ ______________ to examine the minerals in rocks with a special polarizedlight microscope.
23. Magmas with high ___________________ have great difficulty flowing through narrow cracks or other
openings in country rock.
24. If the contacts of a pluton are parallel to the structure of the country rock, the pluton is considered to be
_________________________. An example of this type of pluton is a ____________.
25. A discordant, tabular plutonic body is known as a ____________.
26. _________________ margins can be recognized because they will be more fine-grained than the interior
of the intrusion.
27. In partial melting of rocks in the upper mantle, the first minerals to melt will be the constituents of
granite; that is, they will be richer in _____________.
28. ______________________ of continental crust is an alternative source for the granitic magmas of
batholiths.
29. Increasing the amount of pressure on minerals will generally
a. make them melt
b. lower their melting temperatures
c. raise their melting temperatures
d. have no effect on their melting temperatures
30. Granite, a coarse-grained igneous rock, forms when
a. mafic magmas cool slowly
b. felsic magmas cool slowly
c. mafic magmas cool quickly
d. felsic magmas cool quickly
31. Which pair of igneous rock names represents the most mafic members of the igneous rock family?
a. andesite and diorite
b. rhyolite and granite
c. gabbro and basalt
d. granite and gabbro
32. Which pair of igneous rock names represents the most felsic members of the igneous rock family?
a. andesite and diorite
b. rhyolite and granite
c. gabbro and basalt
d. granite and gabbro
33. Which pair of igneous rock names represents the intermediate members of the igneous rock family?
a. andesite and diorite
b. rhyolite and granite
c. gabbro and basalt
d. granite and gabbro
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