Exam 1 Flashcards
What are the characteristics that fulfill the definition of a mineral?
Naturally occurring
Inorganic
Solid
Forms a crystalline structure
Chemically homogeneous
What are the definitions of the common physical properties used for identifying minerals?
extrusive - cooled above the surface (volcanic)
intrusive - cooled below the surface (plutonic)
What are the relative abundance of major elements in Earth’s crust?
Silicon and oxygen
What is meant by the rock cycle?
The rock cycle is the how material in the earth goes through the process of forming into different types of rocks
The life cycle of rock and minerals
What is magma?
molten rock below the surface
What is lava?
molten rock above the surface
What is the source for magma?
water within oceanic crust is brought into the mantle in a subduction zone. water is released into the surrounding hot mantle rock at a depth of about 100km and promotes melting
What are the mechanisms that trigger rock to melt at depth?
a decrease in pressure will allow rocks to melt
magma with more water will remain a liquid at a lower temp
heat transfer
What are the different magma types?
Mafic
Intermediate
Felsic
How do the different magma types compare in composition?
Mafic - dark colored minerals
Intermediate - mix of light and dark minerals
Felsic - light colored minerals
What are the different processes that can affect a magma’s final composition?
Assimilation - new minerals are added to the magma from surrounding country rock
Magma Mixing - magma chambers combine together
Partial Melting - induce melting of solid rock
- minerals with higher silica content melt first
Fractional Crystallization - crystals form from magma cooling and settle to floor of chamber
Know major points of Bowen’s Reaction Series
dark colored minerals are the first minerals to crystallize
light colored minerals are the last minerals to crystallize
How are igneous rocks classified?
Magma types: Mafic, Intermediate, Felsic
Texture: extrusive and intrusive
What are the forms chemical weathering?
Dissolution
- minerals dissolve in water
- salts and carbonates are susceptible
- H2O acidity can be important
Hydrolysis
- the replacement of cations in mineral structures using H+ ions
- affects silicates
Oxidation
- minerals react with oxygen to form an oxide
What are the forms of physical weathering?
Decrease in pressure - results in expansion
Frost - expansion with water and ice
Roots - can work into the fractures and make them bigger
Salt - mechanical weathering of granite from salt on coastline
What are the major clastic sedimentary rocks?
Shale
Siltstone
Sandstone
Conglomerate
How are clastic sedimentary rocks classified?
grain size
sorting
roundness
What are the major chemical sedimentary rocks?
Evaporites - halite, gypsum
Chemical Limestone (travertine)
Biochemical Limestone
Chert - microcrystalline silica
Coal
How do chemical sedimentary rocks form?
Evaporites - precipitate when water evaporates
Chemical Limestone - precipitation of calcium carbonate from ground and surface water
Biochemical Limestone - calcium carbonate becomes incorporated into marine organism shells and skeletons
Chert -
Coal - a sedimentary rock derived from plant remains
What are the sedimentary environments where particular sedimentary rocks are found?
Alluvial Fans - poorly sorted
Fluvial (river) Environment
Desert
Delta
Clastic coastlines
Lakes
Glacial Environments
Shallow marine environment
What causes rocks to metamorphose?
heat and/or pressure of an existing rock(protolith)
What are the different things that can happen to a rock when it undergoes metamorphism?
Neocrystallization - growth of new minerals that are different from the starting rock; atoms migrate or diffuse through solid crystals and/or dissolve and re-precipitate at grain boundaries
Recrystallization - change the shape and size of grains, but not the mineral identity
Phase changes - mineral changes into another mineral with same composition but different crystal structure
Pressure solution - minerals prefentially dissolve at grain boundaries where stress occurs
Mineral migration/remobilization
Physical changes - deformation, rotation, shearing
How are metamorphic rocks classified?
Foliated
Non-foliated
What is foliation?
directed pressure/differential stress
directional/parrallel alignment or banding