Tectonic geomorphology

Question 1

What is important to consider when looking at tectonic geomorphology?

Answer 1

Time scale

Question 2

What does a strainmeter measure?

Answer 2

Strain over time

Question 3

Finding the long term trend of what is critical?

Answer 3

Long term trend of deformation rates

Question 4

What do slip rates give an idea of?

Answer 4

Time scale

Question 5

What can subduction cause?

Answer 5

Severe earthquakes

Question 6

What is needed to date features?

Answer 6

Well defined markers

Question 7

How can you identify a young fluvial terrace?

Answer 7

Young terraces aren’t deformed

Question 8

How can you identify older fluvial terraces?

Answer 8

They have shifted along

Question 9

What happens to a river if a fault activates?

Answer 9

The river becomes disrupted

Question 10

Why does Faults Propagation need to be implemented?

Answer 10

In an active fault segment, the deformation rate varies so fault zones have varied seismic behaviours

Question 11

What is the theory behind the earthquake cycle?

Answer 11

The size of an earthquake depends upon the amount of time since the previous earthquake

Question 12

Explain the uniform earthquake model

Answer 12

Taking into account fault segmentation, the slip-at-point is constant which means that small catch up events are needed

Question 13

What is the slip-at-point?

Answer 13

It is constant on a central “simple” segment with more complex geometry

Question 14

Explain the variable slip model

Answer 14

Slip-at-point varies from event to event, it is random and there is no pattern

Question 15

What are along-fault variations in slip distribution not filled with?

Answer 15

They are not filled with catch up events but reflect variations in long-term slip rate along the fault and or segmentation of the fault zone

Question 16

What are short term data within?

Answer 16

The seismic cycle (2-3 ka)

Question 17

Give 4 examples of data that can be used to quantify deformations

Answer 17

Seismological data
Paleoseismology data
Geodesy
Historical data

Question 18

What are two issues with short term data?

Answer 18

Variable by faults

Variable with distribution of population today and in the past

Question 19

What does long-term data do?

Answer 19

Average the seismic cycle (2-100ka)

Question 20

What are 3 types of long term data for quantifying deformations?

Answer 20

Tectonic geomorphology
Morphochromology
Average quaternary slip rate

Question 21

What is the rate equation?

Answer 21

Rate = distance / time

Question 22

What is rate?

Answer 22

This is the slope of the linear regression between terrace ages and their offsets

Question 23

What two things are needed to estimate the general trend of slip-rate estimates from goemorphologic evidence?

Answer 23

Well-defined and well-preserved geomorphic offset markers

Datable markers

Question 24

Give 4 examples of geomorphic offset markers

Answer 24

Fluvial terraces
Alluvial fans
Moraines
Outwash, channel

Question 25

How do fluvial terraces work?

Answer 25

Emplacement of a terrace at the time of a large sedimentary discharge which buries the fault. After some energetic discharge the stream incises the channel and the original terrace is abandoned and begins to record faulting, but the riser is constantly refreshed by lateral cutting. During a new episode of entrenchment the terrace is abandoned and there is now a passive marker between this terrace and the original which records lateral displacement.

Question 26

What is an issue with river terraces?

Answer 26

All episodes may not be recorded by all rivers and older terraces can be eroded by further incision

Question 27

What can be used to determine the rates of slip, uplift and shortening?

Answer 27

Vertical offsets, ages and fault geometry

Question 28

What 3 things show evolution of a normal fault?

Answer 28

Triangular facets Perched valleys Sinuosity of mountain front

Question 29

What 6 tools are there that can be used for dating?

Answer 29

``` Field and imagery analysis Qualitative and quantitative mapping Digital Elevation Motion(DEM) Geochronology Syntheses Physical modeling ```

Question 30

The rates of what 7 things can be found from morphochronology?

Answer 30

``` Deformation Uplift Erosion Incision Deglaciation Glaciation ```

Question 31

What are 6 morphochronological dating techniques?

Answer 31

``` Lichenometry Carbonate coatings Radio carbon dating Luminescence Cosmogenic nuclide dating U-Th/He ```

Question 32

How does lichenometry work?

Answer 32

Lichen growth determines the age of the exposed rock

Question 33

What is a requirement for lichenometry?

Answer 33

Local calibration curve

Question 34

What are the issues with lichenometry?

Answer 34

Delay between exposure and calibration curve Varying growth rates from region to region Growth rates may vary over time Short historical timescale

Question 35

What is the timescale for lichenometry?

Answer 35

400 years

Question 36

What are carbonate coatings?

Answer 36

Pedogenic carbonate is amenable to uranium-series dating, such dates provide estimates o the age of the host rock and paleoclimate proxy records contained in the carbonate itself

Question 37

What are the requirements for carbonate coatings?

Answer 37

Local calibration curve

Question 38

What are the problems with carbonate coatings?

Answer 38

Delay between host and exposure and coating development | Varying growth rates that vary over time

Question 39

What is the timescale for carbonate coatings?

Answer 39

Less than 0.5 Ma late pleistocene holocene

Question 40

What is radiocarbon dating?

Answer 40

A radiometric dating method that uses the naturally occurring radioisotope carbon 14 to determine the age of carbonaceous materials

Question 41

How far back does radiocarbon dating go?

Answer 41

Up to about 60,000 years

Question 42

Explain radiocarbon calibration

Answer 42

Calibration curve shows radiocarbon age vs calendar years, there is then a range of possible calendar ranges

Question 43

When can dendrochronology calibration be done up to?

Answer 43

11ka

Question 44

When can U/Th calibration be done up until?

Answer 44

45ka

Question 45

What are 4 methods of morphochronology?

Answer 45

Radiocarbon dating Thermo luminescence (OSL) Cosmogenic nuclide dating U-Th/He

Question 46

How does cosmogenic isotope dating work?

Answer 46

Cosmic rays hit targets to produce products

Question 47

Explain the altitude dependence

Answer 47

Attenuation through the atmosphere

Question 48

Explain the latitude dependence

Answer 48

The Earth's magnetic field deflects the charged particles of the cosmic ray flux

Question 49

How does quantitative morphology work?

Answer 49

Measure the offsets by matching piercing points on both sides of the fault

Question 50

What happens if there is lots of soft sediment?

Answer 50

There are more layers

Question 51

What is an issue with radiocarbon dating?

Answer 51

Difficult to find materials that can be radiocarbon dated

Question 52

Give two examples of materials that can be radiocarbon dated?

Answer 52

Charcoal and some shells

Question 53

What element is used for cosmogenic isotope dating?

Answer 53

This is non-atmospheric CO2 or an element that is not contained in the rock

Question 54

What increases the production rate?

Answer 54

Higher latitudes and altitudes have higher production rates