Freeman-Lynde GLY116 Cryptozoic Tectonics Questions

The early continental crust of the Earth (during Hadean time) may have nucleated around meteorite impacts.
The earliest crust of the Earth (during Hadean time) probably was no different in composition than the present continental crust.
The earliest crust of the Earth (during Hadean time) probably was very different in composition than the present continental crust.
Ultramafic & mafic magmas are generated by partial melting of andesitic & granitic precursors.
When did most of the differentiation of the Earth take place based on the age of the oldest continental rocks?
A. 100 million years ago B. 500 million years ago C. 1 billion years ago D. 2.5 billion years ago E. 3.8 billion years ago
Andesitic & granitic crust is generated by ________ (process) of precursors containing less silica (mafic/ultramafic compositions).
The early ___________ of the Earth (during Hadean time) may have nucleated around meteorite impacts.

Precambrian rocks on different continents are correlated using biostratigraphic methods.
Precambrian shields are not found on all of the continents.
Archean cratons are usually surrounded by Proterozoic mountain belts.
The Superior & Slave provinces are examples of _____________.
The Superior, Slave, Nutak, Kaminak, & Wyoming provinces are examples of:
A. Early Proterozoic mountain belts. B. Middle Proterozoic mountain belts. C. Late Proterozoic mountain belts. D. all of these E. none of these A. Early Proterozoic mountain belts. D. Archean cratons
The oldest known crustal rocks on Earth are _______________________ years old.
In the Canadian Shield, ______________ (age) cratons are usually welded together & surrounded by Proterozoic mountain belts.
3. & 4. In the Canadian Shield, smaller ________________ (age) cratons are usually welded together & surrounded by ________________ (age) mountain belts.
Matching: Match the parts of the Canadian Shield listed on the left with the appropriate description on the right. Each item on the right will be used only once.
- Superior Province A. 1.0 by old deformation
- Rae Province B. Archean craton
- Keweenawan Lavas C. 1.8-1.6 by old deformation
- Grenville Province D. 1.9-1.8 by old deformation that formed proto-Laurentia
- Wopmay Orogen E. 1.3 by old rifting

Primitive continents are represented by the greenstone belts found in Archean cratons.
The granite-gneiss terranes of Archean cratons are thought to represent the primitive oceans.
Archean granite-gneiss terranes represent the Earth's primitive continents.
Archean greenstone belts represent the Earth's primitive continents.
Archean granites show a greater mantle contribution than do Phanerozoic granites.
Feldspars in Archean granites have a different composition (they are Sodium-rich) than the feldspars in Phanerozoic granites (which are Potassium-rich).
Greenstone belts occur only in Proterozoic mountain belts.
Greenstone belts sometimes occur in Proterozoic mountain belts.
Archean greenstone belts contain evidence that the upper part of the Earth's mantle was completely melted during the Archean.
Ultramafic volcanics occurring in Archean greenstone belts indicate that the Earth's interior was hotter/colder during the Archean Eon than at present.
The MAFIC igneous rocks (basalt as pillow lavas & gabbro) contained in Archean greenstone belts indicate that the upper part of the Earth's mantle was completely melted during the Archean.
Archean shallow-marine quartzites & carbonates are abundant.
Archean shallow-marine quartzites & carbonates are rare.
Shallow-marine quartzites & carbonates are generally absent in Archean sedimentary sections.
Graded-bedded graywackes deposited in deep-marine are generally absent in Archean sedimentary sections.
Widespread quartzite-carbonate-shale assemblages are typical of the Archean greenstone belts.
Archean plate tectonics had more intense mantle convection, smaller plates, & thinner lithosphere compared to Phanerozoic plate tectonics.
The size of the Earth's lithospheric plates & continents has NOT changed from the Archean to the Phanerozoic.
Archean & Proterozoic crustal evolutionary processes were IDENTICAL.
Archean crustal evolution is dominated by Wilson Cycles.
The Archean rocks of the Canadian Shield were consolidated into a large stable craton called Laurentia 3.8 billion years ago.
Which of the following rock types are restricted to Archean greenstone belts?
B. ultramafic volcanics B. sediments C. felsic volcanics A. granite plutons B. mafic volcanics C. basaltic volcanics D. all of these E. none of these
Which of the following rock types are NOT unique to Archean greenstone belts?
A. granite plutons B. sediments C. ultramafic volcanics D. both A. & B. E. all of these
When did Ultramafic Volcanics form in great abundance?
A. Archean B. Early Proterozoic C. after 2 by ago D. Early Paleozoic E. They're still forming.
What is the geologic significance of the ultramafic volcanics in Archean greenstone belts?
- A. Showing that there were volcanoes during the Archean. E. none of these
- B. Showing that the oceans were deeper during the Archean.
- C. Showing that the interior of the Earth was hotter during the Archean.
- D. Ultramafic volcanics in Archean greenstone belts are not geologically significant.
Which of the following characterized Archean plate tectonics compared to Phanerozoic plate tectonics?
A. more intense mantle convection B. smaller plates C. thinner lithosphere D. both B. & C. E. all of these
Archean plate tectonics had ________ compared to Phanerozoic plate tectonics.
A. more intense mantle convection B. smaller plates C. thinner lithosphere D. both B. & C. E. all of these
Greenstone belts containing ____________________ are restricted to the Archean.
Greenstone belts containing ultramafic volcanics are restricted to the __________________ Eon.
Cryptozoic ____________ contain evidence that parts of the Earth's mantle were completely melted during the Archean.
Sedimentary rocks occurring in Archean greenstone belts are usually graded-bedded graywackes deposited in _________________.
The Earth's primitive continents / oceans (circle one) are represented by Archean greenstone belts/granite-gneiss terranes.

Laurentia probably became part of a true supercontinent (Pangea I) as a result the Grenville/Llano Orogeny.
The initial stage of a Wilson Cycle (the breakup of a supercontinent by rifting followed by dispersion) is NEVER preserved at a continental margin.
The size of the Earth's lithospheric plates & continents has increased from the Archean to the Phanerozoic.
Proterozoic crustal evolution is dominated by Wilson Cycles.
The oldest completely preserved Wilson Cycle occurs in Archean aged rocks.
The separate Archean cratons of the Canadian Shield were consolidated into cratons _________.
A. 4.6 by ago B. 3.8 by ago C. near the end of the Archean D. at the end of the Proterozoic E. at the end of the Paleozoic
The Archean rocks of the Canadian Shield were consolidated into a large stable craton called Laurentia ______________ ago.
A. 4.6 by B. 3.8 by C. 2.5 by D. 570 my E. 245 my
The separate Archean cratons of the Canadian Shield were consolidated into a single craton (Laurentia) following the Wopmay, Trans-Hudson, & Penokean Orogens, that is by ________ billion years ago.
A. 3.8 B. 2.5 C. 1.8 D. 0.9 E. 0.57
____________ represent passive continental margin deposition at the edges of stable Proterozoic cratons.
A. Tillites/diamictites B. Banded iron formations C. Quartzite-shale-carbonate assemblages D. all of these E. none of these
Widespread ________________ Assemblages (3 rock types) represent passive continental margin deposition at the edges of stable Proterozoic cratons.
The initial stage of a Wilson Cycle is represented by ____________.

The suturing of exotic terranes (the Colorado-Central Plains & the Southwestern Provinces) to the south margin of Laurentia was the final tectonic activity affecting Laurentia during the EARLY Proterozoic.
A well developed passive continental margin formed along the western side of the _________ Province in northern Canada was deformed during orogenesis preserved as the Early Proterozoic Wopmay Orogen.
A. Slave B. Churchill C. Grenville D. Wyoming E. none of these
The ________ Wopmay Orogen resulted from deformation of a well developed passive continental margin on the western side of the Slave Province in northern Canada.
A. Early Proterozoic B. Middle Proterozoic C. Late Proterozoic D. Archean E. none of these
The ________________ Wopmay Orogen (the oldest completely preserved Wilson Cycle) resulted from deformation of a well developed passive continental margin on the western side of the Slave Province in northern Canada.
A. Late Proterozoic B. Middle Proterozoic C. both A. & B. D. Early Proterozoic E. Archean
The Early Proterozoic Central Province on the southeast of the North American craton consists of _______________.
A. exotic terranes (island arcs) B. greenstone belts & granite-gneiss terranes C. rift basin sediments/volcanics D. all of these E. none of these

There is no evidence for continental glaciation in Precambrian rocks.
Periods of continental glaciation occurred during the Precambrian.
The first evidence of continental glaciation on Earth occurs in the Phanerozoic.
The first evidence of extensive glaciation occurs in the Middle Proterozoic.
The first evidence of extensive glaciation occurs in rocks of Early Proterozoic age.
The first evidence of continental glaciation on Earth occurs in the Late Proterozoic.
How many episodes of Precambrian continental glaciation were there?
A. 15 B. 7 C. 5 D. 3 E. 2
There were ______ MAJOR intervals of widespread Precambrian continental glaciation.
A. 7 B. 5 C. 3 D. 2 E. 0 A. 0 B. 2 C. 3 D. 5 E. 7
The first evidence of continental glaciation on Earth occurs in the _______________.
A. Pleistocene B. Late Proterozoic C. Middle Proterozoic D. Late Archean/Early Proterozoic E. none of these
The Bruce/Gowganda sequence in N. America record the earliest episode of _______.
2. & 3. The oldest episode of continental glaciation on Earth occurred from _________ years ago to _______ years ago.
The earliest episode of continental glaciation occurred during the _____________________.
The second oldest episode of continental glaciation occurred during the ________________.

Redbeds are widespread in Archean rocks.
Redbeds are widespread in rocks younger than 2 billion years old.
O2 produced by photosynthetic cyanobacteria during the Archean & Early Proterozoic did not accumulate in the atmosphere because it was incorporated into hematite during weathering of iron-rich rocks to form redbeds.
The Archean atmosphere was notably deficient in _____________.
A. carbon dioxide B. free oxygen C. methane D. all of these E. none of these
What was the characteristic(s) of the atmophere during the Archean?
A. No free oxygen. B. Relatively abundant methane (CH4) & ammonia (NH3). C. Relatively abundant CO2. D. All of these E. None of these.
The O2 formed by photosynthetic blue-green algae from 2.5-2.0 billion years ago did not accumulate in the atmosphere because:.
The O2 formed by photosynthetic cyanobacteria from 3-2 billion years ago did not accumulate in the atmosphere because:
- A. it was combined with iron to form redbeds.
- B. it was combined with iron to form banded iron formations (BIFs).
- C. it was combined with hydrogen to form water (H2O). D. all of these E. none of these
The _______ formed by photosynthetic blue-green algae from 2.5-2.0 billion years ago did not accumulate in the atmosphere because it was combined with iron to form banded iron formations.
The _______ formed by photosynthetic blue-green algae from 3-2 billion years ago did not accumulate in the atmosphere because it was combined with iron to form banded iron formations.
A. H2O B. O2 C. CO2 D. all of these E. none of these A. O2 B. NH3 C. CO2 D. CH4 E. H2O
When did Banded Iron Formations form in great abundance?
A. Early Archean B. Early Proterozoic C. after 2 by ago D. Early Paleozoic E. They're still forming.
When did Redbeds form in great abundance?
A. Early Archean B. Early Proterozoic C. after 2 by ago D. Early Paleozoic E. They're still forming.
Redbeds are first observed during the _________________.
A. Archean B. Early Proterozoic C. Middle Proterozoic D. Late Proterozoic E. both C. & D. A. Phanerozoic
What significant change occurred in the atmophere at about 2 billion years ago.
A. Argon began to accumulate. B. Methane (CH4) & ammonia (NH3) began to accumulate. C. Carbon dioxide CO2 began to accumulate. D. All of these E. None of these
\What significant change occurred in the atmophere at about 2 by ago in the Early Proterozoic?
A. Free oxygen begins to accumulate. B. Free methane (CH4) & ammonia (NH3) begin to accumulate. C. Free CO2 begins to accumulate. D. All of these. E. None of these.
During the Archean & Early Proterozoic, oxygen produced by photosynthesis did not accumulate in the atmosphere because it combined with iron dissolved in the ocean to form __________.
Banded Iron Formations (BIF's) are most abundant during the _________________.
Redbeds are first observed during the _____________________.
Redbeds are first observed after _____________________ began to accumulate in the Earth's atmosphere.
_______________ (rock type) are first observed after O2 began to accumulate in the Earth's atmosphere.

The last Cryptozoic tectonic event affecting North America was rifting along both the East & West Coasts (starting about 800 my ago).
The last Cryptozoic tectonic event affecting North America was the suturing of exotic terranes (the Central province) to the south margin of Laurentia.
The Late Proterozoic tectonic history of North America is characterized by widespread continental rifting.
Late Proterozoic tectonics are dominated by widespread continental consolidation associated with the end of a Wilson Cycle.
Late Proterozoic tectonics are dominated by widespread continental rifting & the initiation of a Wilson Cycle.
The Middle Proterozoic Grenville Orogen preserved along the east side of the North American craton represents _________________.
- A. suturing of the Central province exotic terranes to Laurentia
- B. consolidation of North American Archean greenstone belts & granite-gneiss terranes into a single continent
- C. collision of Laurentia (North America) with Gondwana or Eurasia D. all of these E. none of these
Extensive intracrustal granitic/rhyolitic igneous activity, the Mid-Continent Rift & the Grenville Orogeny affected Laurentia during the _________________.
A. Archean B. Early Proterozoic C. Middle Proterozoic D. Late Proterozoic E. both C. & D. E. Phanerozoic
The Late Proterozoic tectonic history of North America is characterized by widespread continental _____________.

Fill-in: In the columns of the diagram below, fill in the names of the 3 Precambrian eons (1-3).
Multiple Choice: The following 5 multiple choice questions apply to the diagram below. Choose the best answer.
- What was the characteristic(s) of the atmophere during the time indicated by "1" in the "Atmosphere" column?
  A. No free oxygen. B. Relatively abundant methane (CH4) & ammonia (NH3). C. Relatively abundant CO2. D. All of these E. None of these.
- What significant change occurred in the atmophere at the time indicated by "2" in the "Atmosphere" column?
  A. Free oxygen begins to accumulate. B. Free methane (CH4) & ammonia (NH3) begin to accumulate. C. Free CO2 begins to accumulate. D. All of these. E. None of these.
- Which interval(s) in the "Rock Types" column is characterized by Banded Iron Formations?
  A. "1" B. "2" C. "3" D. "1" & "3" E. All of these
- Which interval(s) in the "Rock Types" column is characterized by Redbeds?
  A. "1" B. "2" C. "3" D. "1" & "2" E. All of these
- Which interval(s) in the "Rock Types" column is characterized by Ultramafic Volcanics?
  A. "1" B. "2" C. "3" D. "2" & "3" E. All of these
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