Sedimentary basins

Question 1

what are the types of siliclastics rocks

Answer 1

• quartz
• orthoclase and plagioclase feldspar
• lithics

Question 2

what results in different sediment compositions

Answer 2

• weathering and erosion of different parent rocks created in different plate tectonic settings

Question 3

how are sediments categorised

Answer 3

• texture (grain size, sorting, shape)

Question 4

how are sediments classified

Answer 4

• composition (mineralogical constituents)
• texture (grain things hehe)

Question 5

full list of sedimentary characteristics

Answer 5

• composition
• texture
• sedimentary structures
• bedding geometry, style and thickness
• nature of bedding contacts
• fossils
• colour

Question 6

what does the life cycle of a sedimentary rock reflect

Answer 6

• provenance
• transport and deposition
• lithification and diagenesis

Question 7

sedimentary deposition types

Answer 7

• alluvial fan
• fluvial deposition
• deltaic depositoon
• marine deposition

Question 8

what is a sedimentary basin

Answer 8

• a sedimentary basin is a low area in the earths crust, of tectonic origin in which sediments accumulate

Question 9

what shapes can a basin

Answer 9

• doesnt have to be strictly that shape
  -can be deposited on gentle/ uniform slope

Question 10

what is essential to creating sedimentary basins

Answer 10

• tectonic creation of relief
  -source of sediment and low place

Question 11

what is accommodation space

Answer 11

• is the space that is made available within a basin for either marine or non marine sediment to be deposited

Question 12

what is subsidence

Answer 12

• is the gradual downward sinking of the land surface during sedimentation

Question 13

why are sedimentary basins important

Answer 13

• hydrocarbons
• carbon sequestration
• water resources
• ore and mineral resources
• earths history

Question 14

how do sedimentary basins form

Answer 14

• where tectonic activity creates space

Question 15

different types of sedimentary basins

Answer 15

intracontinental basins- interiors far from the margins

foreland basins- craton side of collisional mountain belt

Question 16

what controls accomodation space

Answer 16

• is the combined product movement of
• global sea level
• the sea floor
• changes in rate of sediment accumulation

Question 17

sea level change in response to sedimentary deposition

Answer 17

• shift land/ sea ward in response
• layers of strata and deepening/ shallowing Upward

Question 18

what is transgression

Answer 18

• flooding due to sea level rise
• sediment belt shifts landward and stata deepen upward

Question 19

what is an alluvial fan

Answer 19

• is a fan or cone shaped deposit of sediment built up as a river as it decreases in velocity (often associated with a change in slope)
• like a mountain into a valley and deposition
• ## trunk streams cause accumulations of sediment

Question 20

where is a common place to find alluvial fans

Answer 20

• common in high relief areas (base of a mountain range or below fault scarps)
• sparse vegetation and violet flooding
• humid

Question 21

what can alluvial fans tell us about the area

Answer 21

• about weathering or uplift of a mountain chain

Question 22

most important environment of sedimentary deposits in a geological context

Answer 22

• fault- bounded sedimentary basins where periodic fault movements enable subsidence and preservation of fan sediments

Question 23

composition of alluvial fans

Answer 23

• poorly sorted and gravel dominated
  -down fan increase in sediment sorting
• decrease in grain size and bed thickness

Question 24

what is debris flow

Answer 24

• viscous slurry of material that spreads out as a lobe
• when dense water/sediments

Question 25

what are stream flow dominated fans

Answer 25

- more sheet-like deposits of gravel - moderately well sorted, cross-bedded, laminated or structureless - will be confined to channels on the surface

Question 26

the process of deposition is determined by.......

Answer 26

- availability of water - amount and type of sediment being carried - gradient of the fan surface

Question 27

why are alluvial fans uselful for society

Answer 27

- source of water supply which is important in arid regions

Question 28

2 main categories of fluvial system

Answer 28

- meandering (single channel) - braided

Question 29

controlling factors of fluvial channel morphologies

Answer 29

- grain size - type of sediment load - fluid discharge - discharge regularity - size of drainage area - bank stability - regional slope - tectonic events

Question 30

what is a delta

Answer 30

- supply sediments more rapidly than it can be redistributed - when rivers enter oceans, lakes lagoons ect.

Question 31

what are deltas importance

Answer 31

- site of substancial fossil fuel resource accumulation - grounds for fisheries -

Question 32

the delta sub environments (3 geomorphological elements)

Answer 32

- delta plain- sub aerial, flat swampy plain - delta front- shallow submarine platform where most sand accumulates - pro-delta- most distal water depth 10-15m where bulk suspension settles out

Question 33

what are the controls on delta environments and facies

Answer 33

- eustatic sea level

Question 34

what are the different delta types

Answer 34

- river dominated - tide-dominated - wave-dominated