Dynamic Surface L1

Question 1

What is sediment?

Answer 1

Solid fragmented material that is either eroded from pre-existing rock, chemically precipitated from solution or secreted by organisms which accumulates as layers in loose unconsolidated form.

Question 2

What is an example of sediment?

Answer 2

Mud, sand

Question 3

What is a sedimentary rock?

Answer 3

A rock that results from the consolidation of sediment and diagenesis of minerals.

Question 4

What is a crystalline rock?

Answer 4

Igneous and metamorphic rocks that form as a result of cooling magma etc

Question 5

What kind of rock is a sedimentary rock?

Answer 5

Fragmentary

Question 6

What is the economic importance of sedimentary rock?

Answer 6

Oil and gas
Coal
Mineral deposits
Sand, gravel, building materials
Aquifers
Geothermal energy reservoirs

Question 7

What is a sedimentary facies?

Answer 7

A body of rock with distinct characteristics that reflect the conditions of deposition. Can be carried out on any scale from grain type to large sedimentary structures.

Question 8

Which 2 features of oceans define what sediments are produced and preserved?

Answer 8

Latitude
Water depth

Question 9

Which two broad groups can sedimentary rocks be classified into?

Answer 9

Clastic and non-clastic

Question 10

What is a clastic rock?

Answer 10

A rock made up of fragments of pre-existing rock

Question 11

What is a volcaniclastic rock?

Answer 11

The products of volcanic eruptions or the result of the breakdown of volcanic rocks.

Question 12

What is a terrigenous clastic rock?

Answer 12

Rock that is generated from the land

Question 13

What is a carbonate rock?

Answer 13

Rocks that are mostly non-clastic, formed from shells and skeletons of organisms.

Question 14

What are 6 ways we can classify sedimentary rocks?

Answer 14

Grain size
Grain shape
Grain roundness/sphericity
Grain sorting
Compositional classification
Maturity of sediments

Question 15

Define mud in terms of grain size.

Answer 15

Sediment where you cannot discern individual grains with the naked eye.

Question 16

Define sand in terms of grain size.

Answer 16

Sediment where the grains are visible with the naked eye but less than 2mm on its longest axis

Question 17

Define clasts in terms of grain size.

Answer 17

Larger particles, usually pebbles

Question 18

What is the matrix?

Answer 18

The fine-grained material between grains and clasts in sediments and rocks with a bi-or higher modal distribution

Question 19

What is cement?

Answer 19

Distinct from the matrix - precipitated and grown in pore spaces after deposition

Question 20

What can the grain shape tell us about the sedimentary rock?

Answer 20

How long the grains have been in the depositional system

Question 21

What is an equant grain?

Answer 21

Grains that have equally spaced fracture planes in all directions (e.g. a cube/sphere)

Question 22

What is a discoid/oblate grain?

Answer 22

Grains with one axis shorter than the other two (e.g. a thin cube/sphere)

Question 23

What is a prolate grain?

Answer 23

Grains that are rod-shaped (e.g. long, thin cylinders/cuboids)

Question 24

What are the 4 types of grain shape?

Answer 24

Equant
Prolate
Discoid/oblate
Bladed

Question 25

What is a bladed grain?

Answer 25

Grains that are long and thin (e.g. a long, thin cuboid/cylinder)`

Question 26

What does grain roundness say about the transport of a grain?

Answer 26

The longer the grain has been transported, the higher roundness it will have.

Question 27

How can the roundness of a grain infer the distance from the source?

Answer 27

Increasing distance from the source = increasing roundness

Question 28

Name the stages of roundness from “well rounded” to “very angular.”

Answer 28

Well rounded
Rounded
Sub-rounded
Sub-angular
Angular
Very angular

Question 29

What are the two categories of sphericity?

Answer 29

Low sphericity
High sphericity

Question 30

When talking about the texture of a rock and its grains, which characteristics are being described?

Answer 30

Size, sorting, roundness and sphericity

Question 31

What is grain sorting?

Answer 31

The grain size distribution

Question 32

What is a well-sorted rock?

Answer 32

A rock with a very small grain size distribution (grain sizes are very similar)

Question 33

What is a poorly sorted rock?

Answer 33

A rock with a large grain size distribution (grain sizes are highly differing)

Question 34

What are the main minerals of sedimentary rocks?

Answer 34

Quartz, feldspar, calcite and micas

Question 35

What is the Pettijohn system?

Answer 35

A classification scheme that determines the relative proportions of quartz, feldspar and lithic fragments in a sedimentary rock

Question 36

What are the 3 components of sediment maturity?

Answer 36

Mineralogy
Texture
Size

Question 37

How does mineralogy tell us about sediment maturity?

Answer 37

The more mature a sediment is, the higher the proportion of quartz, the most resistant component, there will be

Question 38

How does texture tell us about sediment maturity?

Answer 38

The more rounded the grains are, the longer they will have been rolled and abraded against each other

Question 39

How does size tell us about sediment maturity?

Answer 39

The smaller the grains, the further they may have
been transported from source and the lower the velocity of the depositing flow

Question 40

What are the characteristics of a supermature rock?

Answer 40

< 15% mud content (arenite)
Well sorted
Rounded grains

Question 41

What are the characteristics of an immature rock?

Answer 41

> 15% mud content (wacke)