Prac Exam 2 Flashcards
The remnant magnetic signature of rocks (paleomagnetism) is an important tool to understand continental drift and inform on past continent reconstructions. What does this remnant magnetic signature show over time for continental rocks and continents?
What is the mantle wedge? (2 marks)
Which part of the mantle is it comprised of? (1 mark)
What is a metamorphic core complex? (2 marks)
A number of geophysically defined boundaries exist as we descend from the surface to centre of the Earth.
a) What is the name of the boundary that defines the base of a tectonic plate? (2 marks)
b) What is an important property that defines this boundary? (1 mark)
c) Is the depth of this boundary from the Earth’s surface always the same across the globe? YES/NO (1 mark)
In what tectonic setting (ie., contractional, transform, extensional, stable cratonic) would you most likely find such a complex forming? (1 mark)
Which one of the following mountain ranges have been formed by continental collision at a convergent plate margin?
Great Dividing Range
New Zealand Alps
The Andes
The Himalayas
The Rocky Mountains
Which of the following forces is prevalent at divergent plate margins?
Which type of seismic activity is associated with convergent plate margins?
Shallow <70 km deep
Intermediate 70-300 km deep
Deep >300 km
Earthquakes from 0 to 700 km deep
Earthquakes from 10 to 440 km deep
The upper mantle is molten/partially molten to account for mantle convection, magmatism and plate tectonic movement.
YES or NO
Which one of the following mechanisms is now considered to be the most important in explaining the movement of plates?
Ridge push (from mid ocean ridges)
Mantle plumes
Slab pull
Mantle conduction
Gravity
Which of the following is associated with or produced along transform boundaries
Granitic magmatism
Transpressional mountain ranges
Crustal exhumation
Andesitic volcanic activity
Mid ocean ridge
Oceanic trench
Mid ocean ridges are sited above upward convecting mantle convection cells
A passive continental margin is called passive because during continental break-up, rifting was caused by plate tectonic forces such that the underlying mantle played a “passive” role during break-up.
True
False
Which one of the following statements does NOT apply to the lithosphere?
It comprises the crust and uppermost mantle
It is a rigid/brittle layer
It has an average thickness of 7 kilometres
It is thicker under mountain ranges
What is the dominant ultramafic rock type that forms the upper mantle?
Harzburgite
Wherlite
Gabbro
Peridotite
Anorthosite
Eclogite
A tectonic plate comprises
The continental crust.
Continental and/or oceanic crust.
The lithosphere and the topmost part of the asthenosphere.
The crust (either continental or oceanic) and its underlying mantle lithosphere.
The crust (either continental or oceanic) and its underlying mantle lithosphere.
A dacite has a higher silica content than an andesite
True
False
Exhumation describes surface uplift
True
False
Melting of mantle material along convergent margins to make magmas that can erupt along volcanic arcs is by decompression
True
False
The fastest moving tectonic plates have the most amount of subducted oceanic crust (slab) connected to them to create a large slab pull force.
True
False
The mantle source region for mid ocean ridge basalts occurs at greater depth than oceanic island basalts because mid ocean ridges are typically 2-4 km below sea level.
True
False
How are Large Igneous Provinces and hostpot volcanism explained by mantle plume theory?
Explain how the supercontinent cycle can have an effect on apparent sea level rise or fall and the flooding of continents.
Name two mantle source domains defined by radiogenic isotope compositions that are thought to originate from ancient subduction.
How does the lithospheric mantle differ from the asthenospheric mantle?
What is the mantle wedge? (2 marks)
Which part of the mantle is it comprised of? (1 mark)
A number of geophysically defined boundaries exist as we descend from the surface to centre of the Earth.
a) What is the name of the boundary that defines the base of a tectonic plate? (2 marks)
b) What is an important property that defines this boundary? (1 mark)
c) Is the depth of this boundary from the Earth’s surface always the same across the globe? YES/NO (1 mark)
