Quizzes Flashcards
(21 cards)
What transition occurs at 410km depth?
• Octahedral to tetrahedral coordination
• Partial melting along grain boundaries
• Spinel to olivine crystal structure
• Perovskite to post-perovskite crystal structure
Spinel to olivine crystal structure
What rock type produces a basaltic magma when it partially melts?
Lherzolite
Dunite
Wehrlite
Harzburgite
Lherzolite
What is a lherzolite?
• >40% olivine with orthoPx and clinoPx
• >40% olivine with clinoPx and <10% orthoPx
• >90% olivine
• <10% olivine with orthoPx
• >40% olivine with orthoPx and <10% clinoPx
> 40% olivine with orthopyroxene and clinopyroxene
What is the physician state of the asthenosphere?
Liquid
Gas
Solid and brittle/rigid
Solid and ductile
Solid and ductile
What is the name of the boundary of the crust and lithospheric mantle?
Low velocity zone
Transition zone
Mohorovičić discontinuity (Moho)
D” layer
Mohorovičić discontinuity (Moho)
What factors control the composition of a primary melt?
Degree of partial melting
Composition of local mantle
Temperature
Addition of volatiles
Pressure
Degree of partial melting
Composition of local mantle
Addition of volatiles
Pressure
What evidence do we have for the mantle being heterogenous in composition?
Composition of mantle xenoliths
Mineralogy of mantle xenoliths
Geophysical data
Lithology of the mantle xenoliths
Composition of mantle xenoliths
What factors would indicate that a magma was NOT a primary melt? (Select all that apply)
Presence of mantle xenoliths
Ni = 350ppm
MgO/(MgO+FeO*) = 0.5
Cr = 900ppm
Ni = 350ppm
MgO/(MgO+FeO*) = 0.5
Cr = 900ppm
From your knowledge of mineral compositions from MinLith last semester, choose the most likely MAJOR rock-forming oxides.
CO2, Na2O, MnO, P2O5, MgO, Fe2O3, Al2O3, Cr2O3, CuO, K2O, NiO, FeO, CaO, H2O, Si02 
Which type of melting could be caused by a mantle plume heating the shallow mantle?
Flux melting
Decompression melting
Heat transfer melting
Heat transfer melting
How do fertile and depleted mantle differ in composition?
• Fertile is enriched in LREE and incompatible elements 
• Depleted is enriched in LREE and incompatible elements
• Fertile is enriched in LREE and compatible elements
• Depleted is enriched in LREE and compatible elements 
Fertile is enriched in LREE and incompatible elements
Which type of melting could be caused by dehydration of amphiboles in a subducting slab?
Decompression melting
Flux melting
Heat transfer melting 
Which type of melting could be caused by mantle convection rapidly bringing hot material into the shallow mantle?
Flux melting
Decompression melting
Heat transfer melting
Are the first minerals to crystallize always present in the final rock?
Yes
No
No
More polymerization in a silicate melt leads to:
Lower viscosity, lower density
Higher velocity, lower density
Lower viscosity, higher density
Higher viscosity, higher density
Higher viscosity, lower density
What factors affect how much melting is required before melt can be extracted?
Crystal melt fractions
Viscosity
Dihedral angle
Density
Crystal melt fractions
Viscosity
Dihedral angle
In the kyanite andalusite sillimanite system, how many phases are there in the whole diagram?
0
1
2
3
3
The solidus is the line on a phase diagram:
Below which everything a solid
Above which liquid is present
Above which everything is liquid
Below which solid has present
Since SiO2 is not as sensitive for evolution of basalts, which oxide is used instead on the x-axis of a basaltic Harker Diagram?
MgO
FeO
CaO
Al2O3
What is the peritectic?
The line below which some solids are present
The line below which everything is solid
The lowest temperature point at which liquid can exist in the system
The point at which solid and liquid interact to create a second solid 
The point at which solid and liquid interact to create a second solid
What is the eutectic?
The line below which some solids are present
The line below which everything is solid
The lowest temperature point at which liquid can exist in the system
The point at which solid and liquid interact to create a second solid
The lowest temperature point at which liquid can exist in the system
