EAE1011 Test 1 Flashcards
What is ‘Ka’?
1,000 Years
What are the Periods in order?
- Cambrian
- Ordovician
- Silurian
- Devonian
- Carboniferous
- Permian
- Triassic
- Jurassic
- Cretaceous
- Tertiary
- Quaternary
Which plat subducts
Denser plate always subducts
What is ‘Downgoing’?
Being subducted
What is ‘Overriding’?
Goes over the other plate
What is a mineral?
An element or chemical compound that is normally crystalline and that has been formed as a result of geological processes
What is a key characteristic of minerals
Most minerals are crystalline, that is:”ordered,three-dimensional arrangements of atoms”.
What is the Geological significance of minerals?
- Indicates pressure/temperature which a rock formed
- Minerals determine the geophysical properties of rocks.
- Minerals react with water and determine its composition
- Minerals and their surfaces control many processes in the environmental chemistry
When did the atoms form?
The first atomic nuclei formed about 3 minutes after the big bang
What main processes fuse atomic nuclei?
Many different processes can fuse atomic nuclei, however the two main types are:
- Stellar nucleosynthesis
- Explosive nucleosynthesis
How are heavy elements created?
Heavy elements are mainly produced in supernova explosions
Neutron star mergers also create supernova
These explosions have enough energy to slam nuclei together with sufficient force to form the larger nuclei
Definition
Minerals
5 points
- Are Naturally occuring
- Are inorganic
- Are solids
- Have a definite chemical composition
- Have an ordered atomic arrangement
What are the main minerals meteorites contain?
Meteorites contain 4 main minerals
- Olivine
- Pyroxene
- FeNi metal
- Feldspar
What is the earth and other rocky plannes made from?
Same minerals as meterorites
- Olivine
- Pyroxene
- FeNi metal
- Feldspar
What is the Hadean earth?
4,567 to 3,900 Ma
A geologic eon of the Earth pre-dating the Archean
When did the moon form?
The moon formed 4,477 Ma
Key points
What are the characteristics of the Hadean?
List of 3
- Headean earth had a magma ocean
- Lower mantle may have been solid in the Hadean
- Metal would sink through magma ocean and pond on the solid lower mantle
- Molten metal would migrate to the core
What is the relationship between iron on earth and the moon?
Density indicates the moon is depleted in iron (has a smaller than expected core).
Earth is enriched in metallic iron (it has a larger than expected core).
What is the Continental crust made from ?
Mainly made up of
- Quartzite
- Granite
- Limestone
What is the oceanic crust made from ?
Mainly made up of basalt (bluestone)
What is Mantle made from?
Mostly Olivine
What is Isostasy?
The process whereby the crust floats on top of the mantle because the crust is less dense.
What can ice do to plates?
The continental plates can bend like a beam when the weight of the ice is placed on top of it.
What is a ‘Ma’?
1,000,000 years
I.e. on Million years
What is ‘Ga’?
1 Billion Years
1,000,000,000 year
What is photosynthis?
Evolution of photosynthesis is one of the major events in changing the composition of the atmosphere(decreasing CO₂ increasing O₂)
What is a Bimodal Crust?
Means it has both oceanic and continental crust.
Which planets in the solar system are bimodal?
Earth is the only bimodal planet in the solar system
What are the Eons in order?
- Hadean
- Archean
- Proterozoic
- Phanerozoic
What are the Eras in order?
- Paleozonic
- Mesozoic
- Cainozonic
What is the Lithosphere?
The part of the earth that behaves as a rigid elastic and plastic plate.
What is the Asthenosphere?
The low viscosity mantle that more easily flows
What are Divergent plate margins?
- Found in the middle of ocean
- Have a topography elevated 2-4km plane.
What happens when Plates separate?
When Plates separate mantle surfaces decompresses and a new crust is formed.
What are Convergent plate margins?
- Found at the border of oceans
- Have a depressed topography
- Abyssal plain is called a trench
What are 3 types of convergent margins?
- Oceanic-continental convergence.
- Oceanic-oceanic convergence.
- Continental-contiental convergence
What is the Transform margin?
The Transform Margin is when plates slide next to each other.
What are the driving forces of plate tectonics?
- The release of radiogenic heat.
- The cold dense lithosphere sliding.
- Cold dense slab sinks into the mantle.
What is the effect of plate tectonics on the atmosphere?
Plate tectonics controls the cycle of carbon and oxygen.
Why does the earth not show much evidence of meteoric impacts?
The reasons earth does not show much evidence of meteoric impacts are:
- Erosion
- Plate tectonics
What are Sedimentary rocks?
Formed from breakdown of rocks carried by water and deposited by the ocean.
How are mountains formed?
Rocks are compressed together by plates moving towards each other, subducting or colliding rocks deform in response.
List
Types of rock features
6 items
- Folds
- Anticline
- Syncline
- Faults
- Thrust fault
- Reverse fault
Describe the rock feature
Describe the rock feature Folds ?
Wavelike undulations in rock layers
Describe the rock feature
Describe the rock feature Anticline ?
rock bed dips away from the centre of the fold
Describe the rock feature
Describe the rock feature Syncline ?
beds dip towards the centre of the fold
Describe the rock feature
Describe the rock feature Faults ?
Brittle features where movement occurs on a discrete surface
Describe the rock feature
Describe the rock feature Thrust fault?
A low angle fault
Describe the rock feature
Describe the rock feature Reverse fault?
A steep angle fault.
What is orogenesis?
Another name for continental convergence .
Definition & Symbol
Annum
1 year
Symbol = ‘a’
