Page 443 - Global Tectonics

REVIEW QUESTIONS 425

c. backarc spreading; and 19 How and why might the Early Archean tectonic
d. Benioff plane reversal. regime have differed from that of the present?
10 Explain the main structural differences between 20 Some geologists and geophysicists claim that studies
volcanic and nonvolcanic rifted continental of the structural setting, internal structure, and
margins. Discuss how these two types of margin composition of ophiolites are highly relevant to a
form in terms of continental break-up processes. better understanding of the processes occurring in
subduction zones and at ocean ridge crests. Describe
11 In what ways do the main principles of plate
the evidence derived from ophiolites and provide a
tectonics fail to explain how continental crust
critical review of these claims.
deforms? What types of data are used to determine
how large zones of continental deformation 21 Compare and contrast the properties and mechanical
behave? behavior of continental versus oceanic lithosphere.
22 Explain why studies of isostasy are important in
12 The evolution of continental rifts is thought to be
controlled by a number of competing mechanisms, considering the Earth’s dynamic behavior.
including lithospheric stretching, strain-induced 23 Explain the processes that may be involved in
weakening, and magma intrusion. Explain how the formation of orogenic plateaus at convergent
these mechanisms infl uence rift evolution. margins.
13 Explain how earthquake focal mechanism solutions 24 Summarize the observations that geoscientists have

can give an indication of the stress field in the used to determine when plate tectonics fi rst began
vicinity of the earthquake focus. Cite examples of on planet Earth.
focal mechanism solutions and inferred maximum
25 Describe the data and techniques used in making
and minimum principal compressive stress directions continental reconstructions.
for earthquakes occurring:
26 In what ways have studies of terrestrial heat fl ow
a. at plate boundaries; and
contributed to plate tectonic theory?
b. within plates.
27 Explain the strengths and limitations of
14 What are the controls on the geometry of foreland
paleoclimatological techniques for determining
basins and modes of shortening in foreland fold and
past plate motions and geographies.
thrust belts?
28 Describe the evidence for plate tectonic processes
15 Describe the generalized morphology of a
being operative in Proterozoic times.
subduction zone, explaining all the features
described in terms of a subduction model. 29 Explain the types of metamorphism that are
expected within the different provinces of
16 Formulate a possible “life cycle” for an ocean basin
convergent margins.
within the framework of continental drift, sea fl oor
spreading, and plate tectonics. Give present day 30 Discuss the role of supercontinents within the basic
examples to illustrate various stages in your framework of plate tectonics.
proposed cycle. 31 Summarize the main characteristics of Large
Igneous Provinces (LIPs) and the principal
17 Describe the physical and chemical properties of
observations that constrain their possible origins.
Archean cratonic mantle lithosphere and explain
Explain why these features are important in the
how these characteristics have contributed to its
tectonic evolution of the planet.
long term survival. Discuss at least two models that
explain how the Archean lithosphere may have 32 Describe the physical changes to a convergent
formed. margin that occur as a result of arc–continent
collision
18 Provide a detailed description of the igneous rock
suites that are expected in different tectonic 33 Evaluate the pros and cons of applying the basic
environments. How are the Archean suites similar tenets of plate tectonics to explain the origin
to and different from those that characterize and evolution of economically viable mineral
Phanerozoic times? deposits.