Final Exam Questions Flashcards
- Why do magmas rise from the mantle and lower crust?
magmas rise from the mantle and lower crust due to a combination of heat, buoyancy, pressure release, and tectonic processes.
What is the difference between a royalties and a basalt?
Rhyolite is higher in silica and alkalis than basalt
A rock with a porphyritic:
Igneous
What are phenocrysts?
a. small crystals in the groundmass that surrounds larger crystals in an igneous rock
b. large crystals that are imbedded in the groundmass in an igneous rock
c. small crystals in the groundmass that surrounds larger crystals in a sedimentary rock
d. large crystals that are imbedded in the groundmass in a sedimentary rock
B. Large crystals that are imbedded in the ground mass in an igneous rock
A mafic magma:
Rich in Mg and Fe, low silica, high temp and dark color
As a mafic magma cools what are the first minerals to crystallize?
Ca-rich plagioclase and Mg-rich olivine
The higher temperature minerals in the bowen’s reaction series are enriched in _______ lower in ________ than the lower temperature minerals.
High in Magnesium(Mg) and low in iron(Fe)
What minerals comprise the discontinuous portion of the Bowen’s reaction series?
a. olivine, pyroxene, amphibole and biotite
b. alkali feldspar, quartz and muscovite
c. anorthite, labradorite and oligoclase
d. augite, hornblende and forsterite
A
What minerals comprise the continuous series of the Bowens reaction series?
a. olivine, pyroxene, amphibole and biotite
b. alkali feldspar, quartz and muscovite
c. anorthite, labradorite and oligoclase
d. augite, hornblende and forsterite
C
What minerals comprise the residual phases of the Bowen s reaction series?
A. olivine, pyroxene, amphibole and biotite
B. alkali feldspar, quartz and muscovite
C.anorthite, labradorite and oligoclase
D. augite, homblende and forsterite
B
As plagioclase crystallizes, it is more enriched in ________
than the melt.
A. Ca and Al
B. Me and fe
C. Na and Si
D. Cu and Li
A
As olivine crystallizes, it is more enriched in _____
than the melt
Mg and Fe
- A one-component system
a) consists of a single phase
b) consists of a single chemical species
c) has a phase diagram with only one axis
d) consists of many chemical species on a single phase diagram
B
*The aluminosilicate phase diagram:
a) describes the melting relationship of plagioclase
b) consists of a single mineral phase
c) consists of a single component
d) is relevant only to the lower mantle
C
*The lines separating the stability fields for kyanite, andalusite and sillimanite:
a) have 0 degrees of freedom
b) have 3 degrees of freedom
c) are reaction lines or phase boundaries
d) both b and c
C
*Metamorphic facies refers to:
a) specific conditions of temperature and pressure
b) outcrops of metamorphic rocks
c) various mountainous terrains
A
The conditions for high grade metamorphism include:
a) low pressure and high temperature
b) low pressure and temperature
c) high pressure and temperature
C
The conditions for low grade metamorphism include:
• a) low pressure and high temperature
• b) low pressure and temperature
• c) high pressure and temperature
B
Regional metamorphism occurs:
a) when rocks are buried and subjected to increase in temperature and pressure
b) in tectonic belts where the crust is highly deformed
c) when rocks are carried to great depth by large-scale faults
d) all of the above
D
Feldspathoids are unstable in the presence of
A. quartz
B. corundum (aluminum oxide)
C. muscovite
D. orthoclase
A
The solvus shows:
A. the composition of the solid phase that is in equilibrium with the melt phase
B. the composition of the melt phase that is in equilibrium with the solid phase
C. the composition of two immiscible solid phases that are in equilibrium with each other
D. the composition of the mantle that is in equilibrium with the crust
C
The liquidus shows:
A. the composition of the solid phase that is in equilibrium with the melt phase
B. the composition of the melt phase that is in equilibrium with the solid phase
C. the composition of two immiscible solid phases that are in equilibrium with each other
D. the composition of the mantle that is in equilibrium with the crust
B
The solidus shows:
A. the composition of the solid phase that is in equilibrium with the melt phase
B. the composition of the melt phase that is in equilibrium with the solid phase
C. the composition of two immiscible solid phases that are in equilibrium with each other
D. the composition of the mantle that is in eguilibrium with the crust
A
As a mafic magma cools what are the first minerals to crystallize?
A. Ca-rich plagioclase and Mg-rich olivine
B. Na-rich plagioclase and Fe-rich olivine
C. Ca-rich olivine and Mg-rich plagioclase
D. Na-rich olivine and Fe-rich plagioclase
A
Quartz is unstable in the presence of:
A. alkali feldspars
B. corundum (aluminum oxide)
C. plagioclase
D. muscovite
B
The polymorphs of quartz that form at high temperature and low pressure are
A. albite and anorthite
B. stishovite and coesite
C. crystobalite and tridymite
D. andradite and diopside
C
The most abundant mineral in earths crust are
Feldspar
The solid solution series for feldspars that involve Ca Na and Al Si coupled substitutions is:
albite (NaAlSi₃O₈) and anorthite (CaAl₂Si₂O₈).
The solid solution series for feldspars that involves Na and K substitution is:
(K,Na)AlSi₃O₈
A silicic magma:
High silica and light color
Crystal fractionation of plagioclase pushes the melt to higher _________.
Silica
The polymorphs of quartz that form at very high pressures are_________.
coesite and stishovite.
