Lecture 1

Question 1

define a siliciclastic

Answer 1

siliciclastics are dominated by mineral grains (clasts) and have undergone transport which affects the mineralogy and texture.

Question 2

how much transportation do siliciclastics and carbonates undergo?

Answer 2

Siliciclastics can undergo a significant amount of transportation, carbonates undergo little transportation as they are mostly deposited near where they are created.

Question 3

the presence of carbonate rocks in the rock record tells us what?

Answer 3

That the supply of siliciclastic sediment has been turned off or deflected away.

Question 4

Gaps in the rock record are caused by what?

Answer 4

They are caused by a lack of preservation conditions, which allows erosion to occur

Question 5

What are the two types of conditions you need to think about with preservation potential?

Answer 5

Allogenic and Autogenic conditions

Question 6

discuss allogenic and autogenic conditions

Answer 6

Autogenic conditions: Factors are inherent to the environment that control preservation, they are natural variations in setting.

Allogenic conditions: Factors are imposed upon the environment that control preservation, external forces such as tectonics, sea level change and climate.

Question 7

How do you increase or decrease sediment production?

Answer 7

To increase sediment production you should increase elevation, to decrease sediment production you shoudl decrease elevation. You could also increase rainfall which increases weathering and transport.

Question 8

what is the part in between the continental shelf and slope called?

Answer 8

The shelf break or offlap

Question 9

What is the slope on the continental shelf?

Answer 9

<0.5

Question 10

What is the slope on the continental slope?

Answer 10

<4

Question 11

which two areas are directly affected by sea level change?

Answer 11

Continental shelf and coastal plain

Question 12

Give two examples of rates

Answer 12

Rate of sea level rise or fall, rate of sediment supply

Question 13

decrease in eustatic sl does what to relative sea level?

Answer 13

Causes it to decrease also

Question 14

Discuss the difference between eustatic and relative sea level

Answer 14

Eustatic sea level is the absolute sea level, or volume of water in the ocean.

Relative sea level is the water level with respect to a local datum, it is affected by tectonic uplift or subsidence.

Question 15

List 3 factors each for why relative sea level may rise or fall. Which of these factors is quickest and slowest to change?

Answer 15

It will rise if: Tectonic subsidence occurs, sediment supply decreases, global sea level rises

It will fall if: tectonic uplift occurs, sediment supply increases, global sea level falls.

Sediment supply is the quickest to change, whilst tectonics are the slowest.

Question 16

Define base level

Answer 16

The position below which rivers cant cut, it is otherwise known as sea level

Question 17

Discuss the river equilibrium profile

Answer 17

Where the concave up surface of a river would attain if everything kept constant for a long time, this is never achieved as it ignores thresholds and lagtime.

Question 18

Accommodation is created by what?

Answer 18

Base level rise

Question 19

Discuss accommodation

Answer 19

It is the space available for sediment to accumulate, in a sea or lake this is below sea level.

Question 20

What is sediment bypass and when does it happen?

Answer 20

When accommodation rate is zero (space is constant), the space available gets filled up. This means that sediment will move through and out the other side which is sediment bypass.