Deck 9: Precambrian Earth and Life History the Proterozoic Eon

Question 1

Most basement rock formed during the Archean and Proterozoic eons.

Answer 1

True

Question 2

Continental red beds formed before banded iron formations.

Answer 2

False

Question 3

During the Grenville orogeny, an ocean basin along the eastern margin of North America was closed.

Answer 3

True

Question 4

Mineral diversity increased after the Great Oxygenation event.

Question 5

The Pacific Ocean is in the later phase of a Wilson Cycle.

Question 6

The Grenville orogeny was the culminating event of the amalgamation of Laurentia.

Question 7

Sandstone-carbonate-shale assemblages are characteristic of the early continental rifting phase of the Wilson cycle.

Question 8

The evolution of Laurentia can be described as continental growth by the accretion of younger terranes to an Archean core.

Question 9

Banded iron formations precipitated in oxygen-rich ocean waters.

Question 10

Fortunately for life, oxygen levels in the atmosphere have been stable over Earth's history.

Question 11

Glaciers were rare during the Proterozoic, as temperatures were too warm.

Question 12

Both the presence of banded iron formations and red beds are evidence that the atmosphere and hydrosphere changed from oxidizing to reducing in the Proterozoic.

Question 13

Orogens are belts of igneous and metamorphic rocks formed by the collisions of cratons.

Question 14

Passive margin deposits are rare or absent during the Proterozoic and thereafter.

Question 15

The Ediacaran fauna of Australia includes many examples of organisms with hard shells and internal body parts.

Question 16

A eukaryotic cell has a well-defined nucleus and organelles, including mitochondria and plastids.

Question 17

The Ediacaran fauna of Australia is an example of preservation of some of the earliest known fossils.

Question 18

The primary source for free oxygen introduced into the atmosphere during the Proterozoic was through photosynthesis.

Question 19

Eukaryotic cells have a nucleus and other internal structures.

Question 20

Sandstone-carbonate-shale assemblages are characteristic of active margin sedimentation.

Question 21

Which biological process may have resulted in the development of eukaryotic organisms from primitive prokaryotic organisms?

A) endosymbiosis
B) abiogenesis
C) stratification
D) progradation
E) outgassing

Question 22

The process by which Rodinia broke apart was ____.

A) accretion
B) rifting
C) underplating
D) orogen
E) abiogenesis

Question 23

Ophiolites are found at ____ plate margins.

A) divergent
B) convergent
C) transform
D) passive
E) rifted

Question 24

The increase in atmospheric oxygen during the Proterozoic was caused by ____.

A) a decrease in worldwide volcanism.
B) a decrease in the size of oceans.
C) photosynthesis by cyanobacteria.
D) the appearance of land plants.
E) formation of banded iron formations

Question 25

The transition from single to multicelled organisms may have started with the specialization of cells in colonies.

Question 26

The Earth's atmosphere became enriched in O₂ during the ____.

A) Devonian
B) Cambrian
C) Mesozoic
D) Proterozoic
E) Cenozoic

Question 27

The stratigraphic sequence of an ophiolite assemblage from top to bottom is ____.

A) deep-sea sediments, pillow basalts, sheeted dikes, gabbro, serpentinite
B) pillow basalts, deep-sea sediments, sheeted dikes, gabbro, serpentinite
C) deep-sea sediments, sheeted dikes, gabbro, pillow basalts, serpentinite
D) serpentinite, gabbro, sheeted dikes, pillow basalts, deep-sea sediments
E) serpentinite, sheeted dikes, gabbro, pillow basalts, deep-sea sediments

Question 28

The three basic divisions of an ophiolite sequence are ____.

A) upper mantle, lower continental crust, and sedimentary rocks
B) oceanic crust, continental crust, and lower mantle
C) upper mantle, upper continental crust, and sedimentary rock
D) upper mantle, oceanic crust, and sedimentary rocks
E) sedimentary rocks, oceanic crust, and continental crust

Question 29

A landmass in the Precambrian made up of North America, Greenland, parts of northwestern Scotland, and perhaps some of the Baltic shield of Scandinavia was ____.

A) Gondwana
B) Laurentia
C) Rodinia
D) Pangaea
E) Antarctica

Question 30

The supercontinent Rodinia consisted of Laurentia and other smaller landmasses.

Question 31

Humans cells are eukaryotes.

Question 32

Which model was developed to explain the opening and closing (creation and destruction) of ocean basins?

A) phylogeny
B) parallel evolution
C) endosymbiosis
D) Grenville orogeny
E) Wilson Cycle

Question 33

Orogens are characterized by ____.

A) rifting
B) high oxygen levels
C) igneous and metamorphic activity
D) extensive glacial activity
E) increased biological diversity

Question 34

Sedimentary rocks made up of alternating thin layers of chert and iron minerals, mostly the iron oxides such as hematite and magnetite, are called ____.

A) banded iron formations (BIFs)
B) limestones
C) sand dunes
D) evaporates
E) blue-green algae

Question 35

Evidence for free oxygen in the atmosphere comes from ____.

A) zircon crystals
B) sandstone-carbonate-shale assemblage
C) multicelled organisms
D) continental red beds
E) tillites

Question 36

Rocks that were formerly part of Laurentia are now mostly in ____.

A) North America
B) South America
C) Europe
D) Africa
E) Antarctica

Question 37

A conglomerate that is formed by glacial processes is called ____.

A) glacial striation
B) tillite
C) erratic
D) glacial duen
E) snowball Earth

Question 38

Slices of ancient oceanic crust composed of mafic-ultramafic complexes, tectonically emplaced onto the continents, are called ____.

A) turbidites
B) ophiolites
C) sandstone-carbonate-shale  assemblage
D) layered intrusions
E) slabs

Question 39

Multicelled organisms first appeared in the fossil record about 4.0 billion years ago.

Question 40

Asia is classified as a supercontinent because it contains more land area than any other continent.

Question 41

The next step in the Wilson cycle for the Atlantic ocean is ____.

A) divergence (spreading)
B) formation of passive continental margins
C) convergence and creation of subduction zones
D) convergence (collision of continental plates)
E) mountain building

Question 42

Ediacaran faunal fossils are rare because they ____.

A) existed for a short time
B) lived in a narrow geographic range
C) were soft-bodied animals
D) are the oldest animal fossils
E) were oxidized in the Great Oxygenation event

Question 43

What is one primary reason that there was so little diversification of life during the Archean and Paleoproterozoic?

A) Prokaryotes reproduce asexually.
B) Eukaryotes reproduce asexually.
C) Prokaryotes and eukaryotes do not interbreed except under special conditions.
D) Prokaryotes reproduce sexually but do not transfer genetic information.
E) Eukaryotes reproduce sexually but do not transfer genetic information.

Question 44

____________________ are deposits that geologists use to indicate glaciation has occurred, but these conglomerates resemble other conglomerates that could have originated from other processes.

Question 45

The ____________________ represented the final stage in the Proterozoic continental accretion of Laurentia.

Question 46

What happened to the carbon dioxide in Earth's early atmosphere?

A) It escaped to space.
B) It remains in the atmosphere today.
C) It moved to the stratosphere.
D) It was incorporated into rocks and minerals.
E) It was incorporated into ocean waters.

Question 47

At the beginning of the Proterozoic, Earth's atmosphere was mostly ____.

A) oxygen
B) nitrogen
C) carbon dioxide
D) water vapor
E) argon

Question 48

Which modern day animal has ancestors represented in the Ediacaran fauna?

A) frogs
B) jellyfish
C) trilobites
D) snakes
E) corals

Question 49

Neoproterozoic glacial deposits are found on all continents except ____________________.

Question 50

The opening and closing of an ocean basin is also referred to as a(n) ____________________.

Question 51

Which rock types are found along passive continental margins?

A) sandstone and granite
B) limestone and granite
C) sandstone, shale, and limestone
D) komatiites and ophiolites
E) ophiolites

Question 52

When did the present style of plate tectonics develop?

A) Archean
B) Proterozoic
C) Paleozoic
D) Mesozoic
E) Cenozoic

Question 53

Eukaryotic cells likely originated from the ____________________ of prokaryotic cells.

Question 54

The ____________________ orogen is the earliest mountain-building event that documents a complete ____________________ cycle of opening and closing ocean basins.

Question 55

The ____________________ ____________________ hypothesis states that widespread glaciers covered Earth and froze the seas during the Proterozoic.

Question 56

The multicelled fauna of the Neoproterozoic is known from all continents except Antarctica, and is collectively referred to as the ____________________.

Question 57

____________________ ____________________ ____________________ are alternating layers of chert and iron oxide minerals that formed in shallow marine environments 2.3-2.5 bya.

Question 58

The boundary between the Archean and Proterozoic is marked by changes in ____.

A) fossil assemblages
B) crustal evolution styles
C) atmospheric composition
D) oceanic composition
E) atmospheric temperatures

Question 59

Approximately 1.1 bya, Laurentia began splitting apart along the ____________________ ____________________.

Question 60

After the fragmentation of Rodinia, it reassembled to form another supercontinent, ____.

A) Nuna
B) Kenorland
C) Vaalbara
D) Laurentia
E) Pannotia

Question 61

What can you conclude about the climate in the Neoproterozoic?

Question 62

Summarize and discuss the fossil evidence indicating that eukaryotic cells appeared as much as 1.2 billion years ago. Give examples of some of these early eukaryotic organisms.

Question 63

Discuss the suite of sedimentary rocks that forms on a passive margin with increasing distance and water depth from the shoreline.

Question 64

Discuss the formation of eukaryotic organisms from prokaryotic organisms. What was required for this transformation to occur?

Question 65

Compare and contrast the phases of a Wilson Cycle. What types of rocks and tectonic structures are distinctive of each phase?

Question 66

What evidence indicates oxygen started accumulating in the atmosphere and oceans during the Proterozoic? How does this evidence support the accumulation of oxygen?

Question 67

Summarize the major differences between the Archean and Proterozoic. When did the Proterozoic begin and end?

Question 68

What are three advantages multi-celled organisms have over single-celled organisms?

Question 69

Describe and discuss the formation of the Proterozoic Banded Iron Formations (BIFs). What are they composed of? Why are these BIFs economically important?

Question 70

What is a supercontinent? Identify the supercontinents of the Proterozoic. Discuss their history.