mountain building (14)

Question 1

American Cordillera and Alpine-Himalaya

Answer 1

Young mountain belts

Question 2

Orogenesis

Answer 2

The processes that collectively result in the formation of mountains

Question 3

Orogeny

Answer 3

A specific episode of orogenesis (mountain building)

Question 4

Collisional mountain

Answer 4

A mountain in which compressive horizontal forces have shortened and thickened the crust. Most major mountain belts are of this type.

Question 5

Four regions of subduction zones

Answer 5

Volcanic arc
Deep-ocean trench
Forearc region
Back-arc region

Question 6

Volcanic arc

Answer 6

Built on the overlying plate

Question 7

Deep-ocean trench

Answer 7

Subducting slabs of oceanic lithosphere bend and descend into the asthenosphere

Question 8

Forearc region

Answer 8

Located between a trench and a volcanic arc

Question 9

Back-arc region

Answer 9

Located on the side of the volcanic arc opposite the trench

Question 10

Volcanic island arc

Answer 10

A chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another

Question 11

Continental volcanic arc

Answer 11

Mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent. Examples include the Andes and the Cascades.

Question 12

Deep-ocean trench

Answer 12

A narrow, elongated depression of the seafloor

Question 13

Forearc

Answer 13

A subduction zone located between a deep-ocean trench and an associated volcanic arc

Question 14

Back-arc

Answer 14

The backside of a volcanic arc when viewed from the trench

Question 15

Back-arc basin

Answer 15

A basin that forms on the side of a volcanic arc away from the trench

Question 16

Accretionary wedge

Answer 16

A large wedge-shaped mass of sediment that accumulates in subduction zones. Here sediment is scraped from the subducting oceanic plate and accreted to the overriding crustal block

Question 17

Forearc basin

Answer 17

The region located between a volcanic arc and an accretionary wedge where shallow-water marine sediments typically accumulate

Question 18

Batholiths

Answer 18

Magma that crystallizes at depth to form massive collections of igneous plutons, most batholiths consist of intrusive igneous rocks that range in composition from granite to diorite

Question 19

What does island arc-type mountain building result from?

Answer 19

The steady subduction of oceanic lithosphere under oceanic lithosphere

Question 20

What does Andean-type mountain building result from?

Answer 20

Subduction beneath a continent rather than oceanic lithosphere

Question 21

What is the result of active continental margins of Andean-type mountains?

Answer 21

Long-lasting magmatic activity and crustal thickening

Question 22

What does Alpine-type mountain building result from?

Answer 22

Episodes of mountain building that occur where two continental masses collide

Question 23

Suture

Answer 23

A zone along which two crustal fragments are jointed together. For example, following a continental collision, the two continental blocks are sutured together

Question 24

Ophiolites

Answer 24

The unique structure of these pieces of oceanic lithosphere help researchers identify the collision boundary

Question 25

Fold-and-thrust belt

Answer 25

A region within a compressional mountain system where large areas have been shortened and thickened by the processes of folding and thrust faulting, as exemplified by the Valley and Ridge province of the Appalachians

Question 26

How were the Himalayas built?

Answer 26

50-30 million years ago

India collided with Asia

Question 27

Taconic Orogeny

Answer 27

Caused the volcanic arc and ocean sediments located on the upper plate to be accreted to the edge of the larger continental block

Question 28

Acadian Orogeny

Answer 28

A second episode of mountain building (about 350 million years ago) continued closing of this ancient ocean basin resulting in the collision of. a microcontinent with North America

Question 29

Alleghanian Orogenty

Answer 29

Occurred between 250 and 300 million years ago when Africa collided with North America

Question 30

Terrane

Answer 30

A crustal block bounded by faults, whose geologic history is distinct from the histories of adjoining crustal blocks

Question 31

Microcontinents

Answer 31

A relatively small fragment of continental crust that may lie above sea level, such as the island of Madagascar, or that may be submerged, as exemplified by the Campbell Plateau near New Zealand

Question 32

Fault-block mountains

Answer 32

A mountain that is formed by the displacement of rock along a fault

Question 33

Basic structure of Basin and Range Province

Answer 33

Fault-block mountains (east west stretching)

Question 34

Delamination

Answer 34

Upwelling and lateral spreading of hot mantle rock, which produced tensional forces that stretched and thinned the overlying crust

Question 35

What does isostasy cause?

Answer 35

Causes mountains to rise, so they remain mountainous long after the tectonic processes that initially created them have ceased

Question 36

What happens if tectonic processes raise a mountain belt “too high”?

Answer 36

The rock at is core will become too weak to support the load and the mountain will spread

Question 37

Isostasy

Answer 37

The concept that Earth’s crust is “floating” in gravitational balance upon the material of the mantle

Question 38

Isostatic adjustment

Answer 38

Compensation of the lithosphere when weight is added or removed. When weight is added, the lithosphere responds by subsiding, and when weight is removed, there is uplift

Question 39

Gravitational collapse

Answer 39

The gradual subsidence of mountains caused by lateral spreading of weak material located deep within the mountains