Exam 2 part 4 Flashcards
About what percent of the earth’s outer core does sedimentary rocks represent and how far down do they go?
They represent about 5% of the earth’s outer 10 miles
What are the 3 things that sedimentary rocks have that are important for economic considerations?
1) Coal
2) Petroleum and natural gas
3) Sources of iron and aluminum
What is Diagenesis?
Chemical/physical/biological changes that take place after sediments are deposited
Where does Diagenesis occur?
In the upper few kilometers of the earth
What does diagenesis include?
The recrystallization of stable minerals from less stable ones and the lithification
What are detrital rocks and chemical rocks?
Detrital rocks are formed from transported sediment as solid particles and chemical rocks are sediment that was once in solution
What are the 4 chief constituents of detrital rocks?
1) Clay
2) Quartz
3) Feldspar
4) Micas
How are sedimentary rocks classified?
According to the type of mineral
What 3 types of shale?
1) Mudstone
2) Sandstone
3) Claystone
What are the two major textures of sedimentary rocks?
1) Clastic (Has pores)
2) Non-clastic (Doesn’t have pores, close together)
What is shale?
Shale is mud-sized particles commonly known as Lamica and is the most common sedimentary rock
3 most common detrital sedimentary rocks?
1) Shale
2) Sandstone
3) Conglomerate and breccia
What is the difference between Conglomerate and breccia?
They are both composed of particles greater than 2mm in diameter but conglomerate has rounded gravels and breccia has angular particles
What are chemical sedimentary rocks?
They are material that has been precipitated, they used to be in a solution
What are 5 common sedimentary rocks?
1) Limestone
2) Dolostone
3) Chert
4) Evaporates (Rock salt/gypsum)
5) Coal
What are 2 organic/biochemical limestones and 2 inorganic limestones?
Organic: Coquina (Coral reef) and Chalk
inorganic: Travertine and oolitic limestone
What is Dolostone and Chert?
Dolostone is secondarily formed from limestone and chert is composted of micro quartz
What is the 4 stages of coal formation and where is it formed?
1) Plant material
2) Peat
3) Lignite
4) Bituminous
formed in a swamp environment
What determines the nature of sediment such as the grain size and grain shape?
Where the sediment accumulated
What are the 3 types of sedimentary environments?
1) Continental (Stream erosian/glacial/wind)
2) Marine (Shallow 200 meters and deep continental shelves)
3) Transitional (Shorelines/deltas/lagoons
What is a sedimentary facies?
When you have two or more units of rocks that have difference characteristics (In other words difference environments) but they are adjacent to eachother. Telling you that the environment has changed over time
What is strata and bedding planes
Strata are horizontal bed planes and bedding planes are what separates the strata
What are graded planes?
Graded planes are grain sizes, fine up top, coarse at bottom, it will tell you about the environment.
How to metamorphic rocks go from?
They go from low grade to high grade
What must the rock be when it goes through metamorphism?
It must remain essentially solid
What is contact/thermal metamorphism?
This is when a rock is changed do to the temperature of magma
What is hydrothermal metamorphism?
Chemical alterations being made to the from hot ion-rich water
What is regional metamorphism?
This is when a rock is changed due to heat and pressure.
What does regional metamorphism usually occur and what does it produce?
Usually occurs during mountain building and produces the greatest volume of metamorphic rocks
What is the most important agent of metamorphism?
Heat
What are two kinds of heat in metamorphism?
1) Contact metamorphism (heat from magma)
2) Geothermal gradient (Heat due to depth)
What does heat and water have to do with metamorphism?
Water with other volatile components, enhances the migration of ions and aids in re-crystallization of existing minerals.
how does crystalization grow in terms of metamorphism?
They grow horizontally in metamorphism, this creates the branding of the rock.
