Tectonics and Climate Readings

Question 1

Montgomery and Willet Date ?

Answer 1

2001

Question 2

What was Montgomery and Willet paper about?

Answer 2

The significance of exogenic processes in the Andes

Question 3

Influence of tectonics on Andes?

Answer 3

Uplift of the Andes began 60 million years ago during late Pleistocene
Continuous uplift driven by collision of the Nazca and South American Plates
Create ‘topographic template’

Question 4

Climate influence on geomorphology of the Andes

Answer 4

more current influences of climatic processes -
due to the Andes longitudinal span runs through range of climatic zones result in differences across the mountainous landscape

1) normal fluvial erosion in Northern Andes = high precipitation = narrow mountain range

2) glacial land sculpting = At higher latitudes glaciers preferentially erode the highest ground in the Southern Andes = excess elevation at the glacial limit and systematic decline in max elevation towards pole

Question 5

Where is tectonics most dominant in the Andes - and why?

Answer 5

In central Andes
there is little erosion in except in big river valleys
= leads to crustal thickening by tectonic wedge propagation
Creates linear Hypsometry

Question 6

Quote from Willet and Montgomery

Answer 6

We view tectonics and erosion as a coupled system with potential for feedback between climate driven erosion and tectonic forcing

Question 7

Raymo and Ruddiman date?

Answer 7

1992

Question 8

Raymo and Ruddiman - about

Answer 8

Uplift of the Tibetan plateau may have caused global cooling in the Cenozoic led the growth of large continental ice sheets in both hemispheres

Question 9

Tibetan Plateaux description

Answer 9

elevation exceeds 4500m
surrounded by high mountain ranges - Himilayas to the South
Southwestern China
Largest area of uplifted crust on earth

Question 10

how did Tibetan Plateau impact in Cenozoic?

Answer 10

Uplift resulted in perturbation of atmospheric circulation on a hemispheric scale
and altered weathering patterns this then resulted in a positive feedback mechanism as glacial erosion further increases erosion and cooling worldwide
Chemical weathering = Increase in drawdown of Co2 = further cooling

Question 11

General Argument supporting Raymo and Ruddiman

Answer 11

That Tectonic processes can impact effect climate changes resulting in changes to global geomorphic landscape (Work in positive feedback cycles)

Question 12

Hilton and West - Date

Answer 12

2020

Question 13

Hilton and West (2020) -

Answer 13

Discusses the ways that mountain building processes effect the carbon cycle

Question 14

How does silicate weathering effect the carbon cycle?

Answer 14

Silicate minerals, eg.olivine, react with CO₂ and water through chemical weathering.
= reaction removes CO₂ from the atmosphere and converts it into bicarbonate ions (HCO₃⁻) in solution. these are then carried to rivers = to oceans sink
Climate silicate weathering strongest in areas that have highest erosion

Question 15

Relationship between erosion rate and co2 flux

Answer 15

Where erosion rates are low - weathering products accumulate and shield underlying rocks = weathering limited by supply as material not exposed for weathering

when erosion rates are high - surface area of rock exposed = higher removal of atmospheric Co2 = erosion limited by other factors eg, temperature, Co2 conc

Question 16

Why do mountainous areas vary in their sink/source relationship to the carbon cycle?

Answer 16

Different mountains underlain by different geology
Sedimentary rocks = carbon rich= carbon source
volcanic rocks = not carbon rich = carbon sink

Question 17

Molnar et al - date

Answer 17

2007

Question 18

Molnar et al (2007) -

Answer 18

tectonic fracturing of rock can result in an increased rate of erosion

Question 19

How does fractured rock increase erosion rate?

Answer 19

reduced rock strength = lower resistance to erosion
broadens the surface area available to erode
disintegration = breaks up into smaller blocks that are easier to transport

Question 20

Evidence demonstrating the significance of fracturing as an endogenic erosive process-

Answer 20

places where tectonic activity lies dormant rapid erosion does not occur despite high rainfall

Question 21

Brain - date?

Answer 21

2010

Question 22

Brain (2010)

Answer 22

new evidence suggests that earths topography is actually cased by viscous stresses from flow in the underlying mantle not just plate movement

Question 23

Impact of mantle movement on topography -

Answer 23

upward mantle flow = positive topography = high relief
Downward mantle flow = = negative topography depressions
Height of topography = direct proportion to intensity and depth of mantle flow
driven by gravitational force

Question 24

Where can we study effects of mantle flow? and why?

Answer 24

Australia
Has been tectonically stable since separation from Antarctica
can study how mantle dynamics effect shoreline and surface features
Drowned Reefs in North eastern Australia = resulted due to subsidence during Miocene as result of mantle flow from Subduction north of Papa New Guinea

Question 25

BLAG Hypothysis - who

Answer 25

Berner et al (1983)

Question 26

what is Blag hypothesis

Answer 26

Co2 governs the global climate and weathering of silicate rocks
Higher Co2 = increased rainfall = greater chemical weathering potential = removes co2 from atmosphere
Inversely - loss tectonic activity - less co2 release - less weathering = colder climate - icehouse system

Question 27

Dissolution reaction

Answer 27

calcite + co2 + water —> calcium + bicarbonates

Question 28

What type of landscapes illustrate the interplay of tectonics and climate acting over a range of spatial and temporal scales?

Answer 28

Karst landscapes
Eg - Dolines

Question 29

What are Dolines?

Answer 29

natural enclosed depression in karst landscapes
range from metres to tens of meteres in both diameter and depth
Found in - kentucky, Namibia, Temperate UK

Question 30

exogenic

Answer 30

formed or occurring on the surface of the earth

Question 31

endogenic

Answer 31

formed or occurring internally, geology. formed or occurring within the earth.

Question 32

weathering

Answer 32

physical or chemical breakdown of rocks and soil in place

Question 33

erosion

Answer 33

The process of transporting weathered rock and soil away from where it was broken down.

Question 34

erosivity

Answer 34

potential of the erosive force

Question 35

erodibility

Answer 35

resistance of the material being eroded

Question 36

Denudation

Answer 36

denudation is the sum of all processes that lower the Earth’s surface

Question 37

exogenic factors that influence weathering

Answer 37

Climate
Vegetation
topography
soil composition
biological activity

Question 38

Endogenic factors that effect weathering

Answer 38

mineral composition
structural features - eg fractures and faults
geological age
tectonic activity

Question 39

key drivers of exogenic processes -

Answer 39

Solar energy - atmospheric and oceanic circulation, influencing weather patterns and temperatures, which affect weathering and erosion.
Gravity - mass movements
water - rainfall rivers and glacier
Wind - aeolian erosion

Question 40

key drivers of endogenic processes -

Answer 40

• Heat from earths interior - Geothermal heat drives processes like mantle convection,
• Radioactive decay - decay of radioactive isotopes generates hear contributes to thermal dynamics
• Movement of tectonic plates
  Pressure - due to overlaying rock layers can lead to metamorphism and formation of new minerals

Question 41

Time scales of exogenic and endogenic processes

Answer 41

Exogenic often much shorter but both can operate at range