Igneous Rocks Flashcards
What are the 3 main categories of rock?
Igneous, Sedimentary, Metamorphic.
What makes up the bulk of the Earth’s crust?
Igneous Rocks. With the exception of the Earth’s core, the remaining solid portion of our planet is mostly igneous rock with a thin layer of sedimentary and metamorphic on the surface.
What are Igneous Rocks?
They are formed from molten rock that solidifies. They were the first rocks to form on earth.
What is magma?
It is the parent materials of Igneous rocks. It is formed by a process called Partial Melting.
What is lava?
Lava is what magma is called when it is on the surface.
What is Partial Melting?
It occurs within the Earth’s crust and upper mantle, in depths up to 250 kilometers below the surface.
How is magma made?
Rocks in the lower crust and upper mantle are near their melting points. Melting begins if confining pressure drops or if volatiles are introduced.
What are volatiles?
They are fluids are gases.
What is the geothermal gradient?
The geothermal gradient is the rate at which the Earth’s temperature increases with depth (~25-30°C/km of depth). Most (80%) of the heat is produced through radioactive decay of isotopes like potassium-40, uranium-238, uranium-235, and thorium-232, some (±20%) is residual heat from planetary accretion.
