Lecture 1 - Earth Structure and dynamics Flashcards
What processes supplied initial heat to the Earth?
Compression and Accretion
After 1 billion years, the earth reached 1800-200 degrees, at a depth of 300-1000km, therefore achieving the melting point of iron. Alongside the iron that fell to the centre of the earth, what other processes occurred that shaped our earth?
2/3rds of material rose, as crust and as volatiles in the atmosphere.
Which two elements are found in large proportions in terms of elemental abundance of the whole earth, but are noticeably reduced in their presence at the crust?
Iron and Magnesium.
Name the main component of the Earth’s crust, and the two main components of its mantle.
Crust - Feldspar KALSi3O8
Mantle - Olivine (Mg,Fe)2SiO4 and Pyroxene (Mg,Fe)2Si2O6
What is Dunite comprised of?
99% olivine and 1% Chromite (black)
What is a mineral?
A naturally occurring, crystalline, inorganic material, with a definite, but not necessarily fixed, chemical structure.
What is the (elastic) lithosphere defined by, and how thick is it?
By an isotherm around 1200 degrees.
100-200km thick.
Name and describe what occurs underneath the lithosphere in rheological layering of the Earth.
The Asthenosphere - hotter, ductile and known as the low velocity zone.
Ocean trenches lie on what sort of plate boundary?What activities characterise them, and are found along the Japan-Kuril-Kamchatka island arc?
Convergent
Explosive volcanism and both shallow and deep earthquakes.
Name the key 5 characteristics of continental collision.
- Low angle thrust faults
- High temperature and pressure volcanism
- deformation of pre-existing rock
- crustal melting
- Erosion of recently uplifted mountains
Fast movements between the North American and Pacific plates have created which type of margin?
Transcurrent
Mid oceanic ridges occur on margins with what velocity?
low
