Chapter 3: Rocks Flashcards
Kansas contains what type of rocks?
Limestone and shake
What is a rock?
aggregates of one or more minerals that make of the Lithosphere
What are rocks classified ‘mode of origin’ groups called?
1) Igneous
2) Sedimentary
3) Metamorphic
Rocks are named based on their what?
Texture & Mineral content
Igneous Rocks
Rocks which form as magma cools and crystallize into a solid state.
Works its way up through the earths layers to the
surface.
Sedimentary Rocks
Can be formed on beaches or places with sand.
Weathering and erosion of rocks to the earth’s surface
(Deposition, Burial, & Lithification)
Metamorphic Rocks
A change from one to another.
Rocks under high pressure & temperature in deep crust and upper mantle.
(Recrystallization into solid state of a mineral)
Intrusive rocks
Igneous rocks that cool under the ground
platonic rocks
Magma
molten rocks located beneath the ground surface
Extrusive rocks
Igneous rocks that form at above ground surface
volcanic rocks
Lava
molten rock on surface that has lost most of its gaseous component (water vapor)
Crystallization
the formation and growth of a crystalline solid from a liquid or gas
The crystal size and texture of a rock is determined by what?
The rate of cooling
The slow cooling of a rock causes the crystals to be what size?
slow cooling = large crystals
The fast cooling of a rock causes the crystals to be what size?
fast cooling = small crystals
A very fast cooling rock causes what to happen?
The rock forms to be like glass.
No mineral crystals are present because they had no time to nucleate and grow.
(volcanic glass)
The classification of an Igneous rock is based off what?
the rocks texture and mineral composition
The four types of Igneous rock textures
- Aphanitic (fine grained) - fast cooling rate
- Paneritic (course-grained) - slow cooling rate
- Porphyritic (two crystal sizes) - cools slowly, but
brought away from heat can fasten up the process - Glassy (no visible crystals) - very fast rate of cooling
Bowens reaction series
Shows the order of mineral crystallization in a cooling melt
Mafic
dark minerals crystallize in high temperatures
Felsic
light minerals that crystallize in cooler temperatures
Magmatic differentiation
the process of generating more than 1 type of rock from a single magma
Granitic Rocks
composed almost entirely of light -colored silicates along with a few dark silicates interspersed
Granitic Rocks are referred to as what?
Give one example.
Felsic
EX: granite
Basaltic Rocks
contain substantial dark- colored silicate minerals and calcium- rich plagioclase feldspar
Basaltic Rocks are referred to as what?
Give one example.
Mafic
EX: basalt
Other compositional groups of naming Igneous rocks
Andesitic and Ultramafic
Sedimentary Rocks
formed from the weathering products of pre-existing rocks and sediment that have been transported, cemented, and lithified into NEW rocks.
Sedimentary rocks can be used to look back on Earth’s history. Why?
Provides clues on past environments.
Rocks often contain fossils
Provides information about sediment transport by water,
wind, ice, ect
Features of Sedimentary Rocks
they are composed of strata, or beds, bedding planes, and fossils
The formation of sedimentary rocks
a) weathering
b) transport (erosion)
c) deposition
d) lithification
Sedimentary rocks:
weathering
the disintegration and decomposition of a rock near the surface
(chemical or physical weathering)
Sedimentary rocks:
Transport (erosion)
movement of sediment downslope (gravity, water, wind, and ice)
Sedimentary rocks:
Deposition
sediment laid down in layers
Sedimentary rocks:
Lithification
transportation of sed. to rocks.
a) compaction
b) cementation
Two classifications for Sedimentary rocks
- Detrital rocks
2. Chemical rocks
What are Detrital rocks?
Provide an example.
rocks composed of individual sediment grains that are lithified together..
EX: shale, sandstone, and breccia.
What are chemical rocks?
Provide an example.
derived from material that was once in solution and precipitates to form sediment.
EX: limestone, quartz, evaporites, and bituminous coal.
What is an evaporite?
Rock salt
Metamorphism
the alteration of rock from one form to another
Low-grade metamorphism
only slightly changed, the original rock still distinguishable
EX: shale to slate
High-grade metamorphism
transformation so complete that the identity of the original rock cannot be easily determined.
EX: shale to gnesis
The three agents to metamorphic rocks
Heat
Pressure
chemically active fluids
metamorphic agent:
Heat
MOST IMPORTANT AGENT. provides energy to drive chemical reactions that recrystallize minerals
metamorphic agent:
Pressure
compact rocks and increase with depth can be associated with vertical or horizontal pressure
metamorphic agent:
Chemically active fluids
groundwater acts as a catalyst for chemical reactions; minerals can be altered
Metamorphism occurs most often when…
during mountain building called regional metamorphism
