Sedimentary/Metamorphic Rocks

Question 1

Generating Sediment

Answer 1

1.) Weathering
2.) Erosion

Question 2

Weathering

Answer 2

Surface or near-surface in-place breakdown of pre-existing rocks by physical and chemical processes
-more cracks/surface area=more to react with water or carbonic acid

Question 3

Erosion

Answer 3

Breaking off/ Removal of Rock or sediment
-Grinding away and removal of the Earths surface materials by moving water, air, or ice

Question 4

Physical Weathering

Answer 4

Joints-Naturally formed fracture in a rock with no displacement
Causes:
1.) Frost/Salt wedging
-expansion of water as it freezes
-formation of salts that expand the crack
2.) Biological Processes
-plant/tree roots growing in rock cracks which expand them
-Lichen which excrete organic acids (oxalic acid) can dissolve minerals (chemical weathering done by organism)

Question 5

Chemical Weathering

Answer 5

1.) Dissolution: Water or weak carbonic acid dissolves minerals
2.) Hydrolysis: Breakdown of a mineral to a second mineral due to reacting with H2O or carbonic acid
(How Feldspar breaks down)

Question 6

Clastic

Answer 6

Composed of fragments or grains derived from the breakdown of other rocks, later cemented together

Breccia: Angular clasts-not transported far
(deposited at alluvial fans)
Conglomerate: Rounded clasts-transported far; tumbled
(found at bends in rivers)

Question 7

How are Sedimentary Rocks Formed?

Answer 7

1.) weathering
2.) Erosion
3.) Transportation
4.) Deposition
5.) Lithification/Diagenesis

Question 8

Diagenesis

Answer 8

All physical, chemical, and biological processes that transfer sediment into sedimentary rocks and that alter the rock after the rock has formed.

Question 9

Biochemical

Answer 9

Formed from material produces by living organisms
Biochemical Limestone:
-Calcium Carbonate from coral or shells
Chalk=form of limestone
Chert=Hard, dark, opaque rock composed of silica with amorphous or microscopic fine-grained textures.

Depositional environment=shallow and deep sea deposits (Where reefs and plankton would be)

Question 10

Coal? Oil?

Organic Sedimentary

Answer 10

Formed from carbon-rich relicts of organisms
coal=vascular plant material
oil shale=clay + organic material, plankton (deep marine or lake; requires heat to form while fossilized)

Question 11

Chemical

Answer 11

1.) Evaporites-salt deposits formed by precipitation of saline water (salt lakes)
2.) Travertine-chemical precipitated CaCO3
3.) Gypsum- Large crystals forming (CaSO4 + H2O)

Question 12

Types of Sedimentary Rocks

Answer 12

1.) Clastic
2.) Biochemical
3.) Organic
4.) Chemical

Question 13

Deposition Environments

Answer 13

Non-Marine:
*Clastic-
conglomerate=River Channel
Breccia=Alluvial Fans
Quartz + Sandstone= Dunes
Siltstone/Shale=Lakes and Floodplains

Marine:
Quartz sandstone= beaches and sand shelves

*Organic
-Oil/Shale=deep marine/lake
-Coal=Swamps

*Chemical
-evaporites=salt lakes
-Gypsum=desert
caves

Question 14

Sedimentary Structures

Answer 14

1.) Bedding
2.) Ripple Marks and Cross Bedding
3.) Mud-Cracks

Question 15

Transgression

Answer 15

Sea-level rise

Question 16

Regression

Answer 16

Sea-level fall

Question 17

Metamorphic Rocks

Answer 17

Rock changes physically or chemically by heat or pressure
Shale-> Schist

Question 18

Protolith

Answer 18

original rock from which a metamorphic rock forms
(can be igneous or sed)

Question 19

Effects of Metamorphism

Answer 19

1.) Recrystallization
2.) Metamorphic rxns/Phase changes
3.) Foliation

Question 20

Recrystallization

Answer 20

Change in grain size due to metamorphism (Minerals remain the same)
Sandstone-> Quartzite

Question 21

Metamorphic Rxns/Phase Change

Answer 21

Change i rocks minerology due to pressure and temp change
(New minerals grow through solid state rxns)
Shale-> Schist

Question 22

Foliation

Answer 22

Development of layering due to preferential alignment of minerals as a result of stress on the rock \
(Can occur during new mineral growth or by realignment of existing minerals)

Question 23

Three metamorphic settings

Answer 23

1.) Contact Metamorphism
2.) Regional Metamorphism
3.) Subduction-Related Metamorphism

Question 24

Contact Metamorphism

Answer 24

Rock heated by intruding magma
-Low pressure, High temp
-often no foliation

Question 25

Regional Metamorphism

Answer 25

Low pressure->High pressure
-Mountain belt

Question 26

Subduction-Related Metamorphism

Answer 26

Blue Schist
High pressure, Low temp

Question 27

Original Shale Minerals

Answer 27

Quartz, K-Feldspar, Plagioclase, Clay

Question 28

Minerals produced by metamorphism of Shale

Answer 28

Chlorite, muscovite, biotite, garnet, staurolite, sillimanite