Lesson 4

Question 1

This fossil can be found on South America and Africa suggesting they were once connected.

Answer 1

Mesosaurus

Question 2

This plant fossil can be found on South America, Africa, India, and Antarctica.

Answer 2

Glossopteris

Question 3

“__________ rocks also preserve fossil remains of ancient
life.”

Answer 3

Sedimentary Rocks

Question 4

“________ is the study of large-scale
movement and deformation of the earth’s outer layers.”

Answer 4

Tectonics

Question 5

The rocks of the ocean floors are rich in ___________ minerals.

Answer 5

Ferromagnesian

Question 6

___________ is the temperature below in which minerals remain magnetic, but aboe which it loses its magnetic properties.

Answer 6

Curie Temperature

Question 7

What is the curie temperature of Magnetite?

Answer 7

585 degrees celcius

Question 8

It is referred to as the “fossil magnetism” on rocks

Answer 8

paleomagnetism

Question 9

This concept explains the parting of seafloor rocks at the ocean ridges

Answer 9

Seafloor spreading

Question 10

Who proposed an explanation for the magnetic stripes on the sea floor in 1963?

Answer 10

F. J. Vine and D. H. Matthews, and independently by L. W. Morley.

Question 11

Which rocks are older? The one near the ridge? Or far from the ridge?

Answer 11

Far from the Ridge

Question 12

The apparent movement of the magnetic pole relative to the continent as a function of time

Answer 12

Polar Wander Curve

Question 13

_____ and _____ are the names given to the northern and southern portions of Pangea, respectively

Answer 13

Laurasia and Gondawanaland

Question 14

____________ are the most commont type of divergent boundary worlwide.

Answer 14

Seafloor spreading ridges.

Question 15

What do you call three rift zones that meet

Answer 15

Triple Junction

Question 16

What analogy is used to describe the ocean floor’s role in preserving the record of polarity reversals?

Answer 16

The ocean floor is likened to a “magnetic tape recorder” throughout history, preserving polarity reversals in alternating bands of normally and reversely magnetized rocks.

Question 17

What role does mantle material play in the process of sea floor spreading?

Answer 17

Mantle material from below rises up when the oceanic plates split, filling the gap and causing sea floor spreading.

Question 18

Enumerate the types of Plate boundaries

Answer 18

Convergent, Divergent, Transform

Question 19

Enumerate the process of Continental Rifting

Answer 19

“As continental rifting begins, crust is stretched, thinned, and fractured (A). Eventually, the continental pieces are fully separated, and oceanic
crust is formed between them (B). The ocean basin widens as divergence continues (C).”

Question 20

“Cite at least three kinds of evidence, other than
paleomagnetic evidence, for the occurrence of plate
tectonics.”

Answer 20

Jigsaw Fit, Geological Fit, Tectonic Fit, Glacial Deposits.

Question 21

What are the types of Deformation

Answer 21

Elastic, Plastic, Brittle

Question 21

Explain what is a Terrane

Answer 21

A terrane is a distinct geological unit or fragment of crustal material with unique characteristics, such as rock type, age, and geological history. Terranes are often transported and accreted onto larger landmasses through tectonic processes, contributing to the formation of complex geological landscapes and the evolution of Earth’s crust.

Question 22

Explain why Subduction zones are, geologically, very active places

Answer 22

”
Subduction zones are geologically active due to the intense tectonic forces involved, resulting in frequent earthquakes and volcanic activity. As one tectonic plate is forced beneath another, the process generates seismic energy and triggers magma formation, leading to earthquakes and volcanic eruptions along the subduction boundary.”

Question 23

Describe the lithosphere

Answer 23

The lithosphere is the Earth’s outermost shell, made up of the crust and the upper mantle. The crust is thinner and less dense than the mantle, and is made up of different types of rock. The mantle is much thicker and is made up of peridotite, a rock rich in magnesium and iron.

Question 24

Describe the asthenosphere

Answer 24

a partially molten layer of rock. This “weak zone” allows tectonic plates to slowly drift by acting like a conveyor belt. Hot plumes from the asthenosphere create new ocean floor, while subducted plates eventually join its depths.

Question 25

What is a triple junction

Answer 25

A triple junction is a fascinating geological phenomenon where three tectonic plates meet.

Question 26

Give an example of a triple junction and plate that correspond to it

Answer 26

Rodrigues Triple Junction (RTJ), also known as the Central Indian [Ocean] Triple Junction (CITJ) is a geologic triple junction in the southern Indian Ocean where three tectonic plates meet: theAfrican Plate, the Indo-Australian Plate, and theAntarctic Plat

Question 27

What is polar wandering

Answer 27

Polar wandering, also known as true polar wander, refers to the apparent movement of the Earth’s solid surface with respect to the planet’s rotational axis. This phenomenon can occur due to various factors, including changes in the distribution of mass on Earth’s surface, such as continental drift, changes in ice distribution, or mantle convection.

Question 27

Give examples of endogenic and exogenic processes.

Answer 27

Endogenic: Plate Tectonics, Volcanism, Earthquakes. Exogenic: Weathering, Erosion, Deposition

Question 28

What consists Gondwanaland

Answer 28

S. America, Africa, Antarctica, Australia, India, Arabia

Question 29

Difference between destructive and constructive margin

Answer 29

Destructive margins involve the convergence of tectonic plates, resulting in subduction, volcanism, and earthquakes. Constructive margins feature the divergence of plates, leading to the formation of new crust through volcanic activity and the widening of ocean basins.

Question 30

What is a suture zone?

Answer 30

”
A suture zone is a geological boundary where two tectonic plates have collided and fused together. It represents the closure of an ocean basin or the collision between continents, marked by intense folding, faulting, and the presence of distinct rock sequences.”

Question 31

What is a Wadati–Benioff seismic zone?

Answer 31

a sloping band of earthquake activity that is typically found in association with subduction zones. These zones are characterized by a series of earthquakes that occur at increasing depths beneath the Earth’s surface, reflecting the downward movement of a tectonic plate into the mantle during subduction.

Question 32

Enumerate all the plate boundaries and the fault the correspond to it.

Answer 32

Transform (strike slip fault), Convergent (Reverse Faults), Divergent, (Normal Faults)

Question 33

How many are the major plates. Name them.

Answer 33

There are 7 major plates: N. American, S. American, Eurasian,African, Antarctic, Indo Australian, Pacific.

Question 34

How did Vine and Matthews describe the magnetism of normally and reversely magnetized rocks affecting the Earth’s magnetic field?

Answer 34

Normally magnetized rocks added to Earth’s current magnetic field, producing slightly stronger magnetization, while reversely magnetized rocks countered Earth’s much stronger field, resulting in apparently lower net magnetic strength.

Question 35

“What causes strain in rocks? How do elastic and plastic
materials diff er in their behavior?”

Answer 35

Strain in rocks is caused by stress from tectonic forces or other factors. Elastic materials deform reversibly under stress, returning to their original shape when the stress is removed, while plastic materials deform permanently, undergoing restructuring. This distinction arises from the ability of elastic materials to store and release energy elastically, whereas plastic materials undergo irreversible changes in shape or structure.

Question 36

“Explain how a subduction zone forms and what occurs at such
a plate boundary.”

Answer 36

A subduction zone forms at a convergent plate boundary when a denser oceanic plate is forced beneath a lighter continental plate or another oceanic plate. As the oceanic plate descends, it generates magma through the melting of the mantle above it. This magma can lead to volcanic eruptions, and subduction zones are also associated with significant seismic activity.

Question 37

“What brings about continent-continent convergence, and
what happens then?”

Answer 37

Continent-continent convergence occurs when two continental plates collide due to the movement of tectonic plates. When this happens, neither plate is dense enough to be subducted beneath the other, so they buckle and crumple, forming large mountain ranges like the Himalayas. This process involves intense compression, folding, and faulting of the Earth’s crust, leading to the uplift of extensive mountain ranges and seismic activity.

Question 38

“Describe how convection in the asthenosphere may drive the
motion of lithospheric plates. Alternatively, how might plate
motions churn the plastic asthenosphere?”

Answer 38

Convection in the asthenosphere drives the motion of lithospheric plates as rising hot material pushes them apart at divergent boundaries and sinking cooler material pulls them down at convergent boundaries. Conversely, the movement of lithospheric plates churns the plastic asthenosphere, deforming and flowing in response to the forces exerted by the plates’ motions at boundaries.

Question 39

Discuss the concept of slab rollback and its implications for the dynamics of subduction zones.

Answer 39

Slab rollback refers to the backward motion of a subducting oceanic plate into the mantle at a convergent plate boundary. This process is often driven by the gravitational pull of the subducting slab, which causes it to sink into the mantle. Slab rollback can lead to extensional tectonics in the overriding plate and may result in the opening of back-arc basins behind volcanic arcs.

Question 40

Explain the differences between continental rifting and seafloor spreading, and how they contribute to plate movement.

Answer 40

Continental rifting involves the gradual splitting apart of a continent due to tensional forces, eventually leading to the formation of a new ocean basin. Seafloor spreading occurs along mid-ocean ridges, where new oceanic crust is formed as magma rises from the mantle and solidifies at the surface. While both processes involve the creation of new crust, continental rifting occurs on a larger scale and leads to the breakup of continents, whereas seafloor spreading primarily occurs within ocean basins.

Question 41

Discuss the difference between subduction and obduction

Answer 41

Subduction involves the downward movement of one tectonic plate beneath another, forming deep ocean trenches and volcanic arcs. Obduction entails the emplacement of oceanic lithosphere onto continental lithosphere, resulting in the uplifting and exposure of oceanic crust and mantle material on the Earth’s surface.

Question 42

Compare and contrast the Wilson Cycle with the supercontinent cycle, and discuss their significance in the context of plate tectonics.

Answer 42

The Wilson Cycle describes the cyclical process of continental rifting, seafloor spreading, subduction, and collision that leads to the formation and breakup of supercontinents. In contrast, the supercontinent cycle refers specifically to the assembly and dispersal of supercontinents over hundreds of millions of years. While the Wilson Cycle focuses on the mechanisms driving plate tectonics, the supercontinent cycle considers the broader geological implications of supercontinent formation and breakup.

Question 43

Evaluate the relationship between plate tectonics and the formation of ore deposits, including examples of specific mineralization processes at tectonic boundaries.

Answer 43

Ore deposits are often associated with tectonic boundaries, where the movement and interaction of tectonic plates create conditions conducive to mineralization. For example, many valuable metal ores form in subduction zones, where fluids released from the subducting slab react with surrounding rocks to concentrate metals in veins and deposits. Similarly, hydrothermal vents along mid-ocean ridges can precipitate minerals from seawater, forming valuable ore deposits on the seafloor.

Question 44

Examine the concept of plate boundary forces, including ridge push, slab pull, and mantle drag, and their relative importance in driving plate motion.

Answer 44

Plate boundary forces drive the motion of tectonic plates and include ridge push, slab pull, and mantle drag. Ridge push results from the gravitational force exerted on newly formed oceanic crust at mid-ocean ridges, causing it to slide downhill away from the ridge axis. Slab pull occurs at subduction zones, where the denser oceanic lithosphere sinks into the mantle, pulling the rest of the tectonic plate along with it. Mantle drag refers to the frictional resistance encountered by tectonic plates as they move over the convecting mantle, which can influence the velocity and direction of plate motion.

Question 45

Relate the concept of rock cycle in Plate Tectonics

Answer 45

Plate tectonics influences the rock cycle by driving the processes of rock formation, alteration, and recycling. At divergent boundaries, magma rises to the surface, solidifying into igneous rocks, while at convergent boundaries, rocks undergo metamorphism due to heat and pressure. The movement of tectonic plates also exposes rocks to weathering and erosion, contributing to the formation of sedimentary rocks.

Question 46

Discuss the concept of the Stress-strain diagram in rocks

Answer 46

The stress-strain diagram in rocks illustrates how rocks respond to applied stress by deforming. It shows the relationship between stress, the force applied per unit area, and strain, the resulting deformation of the rock. This diagram is crucial for understanding the mechanical behavior of rocks, including their elasticity, plasticity, and ultimate failure characteristics.

Question 47

How did early paleoclimates support the plate tectonics theory

Answer 47

Early paleoclimates provided key evidence for the plate tectonics theory by revealing past distributions of landmasses and oceanic currents. For instance, the presence of glacial deposits in locations that are currently near the equator suggested that these areas were once located closer to the poles, supporting the idea of continental drift.

Question 48

“Explain why a mountain chain can be an evidence of a suture zone between
the original colliding continents.”

Answer 48

A mountain chain can serve as evidence of a suture zone between original colliding continents due to the intense tectonic forces involved in their collision. The uplift and deformation of crustal rocks along the suture zone lead to the formation of mountain ranges, characterized by complex geological features such as folding, faulting, and metamorphism, indicating the convergence and welding together of the colliding landmasses.