Class lecture notes part 2 Flashcards
Islands increase in age with ____ from the present hotspot
Distance
Plumes often originate in the ____ ____ boundary beneath _________
Core Mantle, Hotspots
What is a mineral? (5 things)
Naturally occurring
Solid
Ordered crystalline structure
Defined Chemical composition
Inorganic
Minerals make up ____
Rocks
Minerals have a what kind of structure?
Crystalline
Glass is a what?
Solid with disordered atoms
Why do we care about minerals?
Minerals are the building blocks of the planet
Two types of minerals
Industrial minerals and Ore minerals
What are industrial minerals?
Raw materials for manufacturing
What are ore minerals?
Source of valuable metals
Valence Electrons
Electrons in the outer shell of an atom
Valence electrons can be gained lost or shared in what?
Chemical Bonds
All atoms want their outer shell to be either ____, ____, ______ ______
Full, 1/2 full, or completely empty
Some atoms will share a what? (Covalent)
Electron
Other atoms will give away or steal a _________ from another atom (ionic bond)
Electron
What is an Ion
Atom with a different number of protons than electrons
What are Cations
More protons than electrons - Positive charge
Anions
More electrons than protons - Negative charge
Chemical bonds can form ____ dimensional shapes
3
Polymorph
Two minerals with the same chemical formula but a different crystal packing structure
Diamond and Graphite are made out of the same material (Carbon), so why are they so different?
Diamond is packed more tightly
Define Crystals
Constancy of interfacial angles
How can new Crystals form?
Solidification from a melt
Precipitation from a solution
Solid-State diffusion
Biomineralization
Precipitating directly from a gas
How do Minerals form?
Small crystal acts as a seed for growth, Atoms migrate to the seed and attach to the outer face, then growth goes outward from the center
Resulting crystal shape is governed by what?
Surroundings
A crystal growing in an OPEN space will have _____ grow
Crystal faces
A crystal growing in a CONFINED space will have ____ grow
No crystal faces
Anhedral means?
Grown in tight spaces, no crystal faces
Euhedral means?
Grown in an open cavity, good crystal faces
Are Anhedral crystals more or less prevelent?
More
What’s Color (mineral)
Part of visible light that is not absorbed by a mineral
Define Hardness (Minerals you pervert)
Ability of a mineral to resist scratching
Streak
Color of a powder by crushing a mineral (Of hardness less than 6)
Luster
The way a mineral surface scatters light
What is specific gravity
Density or weight of a material
Crystal habit
A single crystal or aggregate with well formed faces
Cleavage
Tendency to break along planes of weaker atomic bonds
Fracture
Implies equal bond strength in all directions
What’s a Rock?
Naturally occurring aggregate of one or more minerals in a solid state
Do manufactured products (concrete, bricks, etc.) count as rocks?
No
Most rocks are made up of multiple ____
Minerals
Some volcanic rocks are made up entirely of what?
Natural glass
Rocks on earth’s surface can occur as ____ or ____ that is attached to the crust
Broken pieces, Bedrock
What is an outcrop
Exposure of bedrock
Who is James Hutton
The dude who developed modern geology
What are Clastic Rocks
They are rocks held together by cement composed of minerals precipitated between mineral gains
What are Crystalline rocks?
Rocks held together by interlocking crystals
Rocks are made out of ____
Chemical Elements
Do all Rocks contain the same elements
No
The most abundant elements in the crust are_______ and _________
Silicon (Si) and Oxygen (O)
What is a Genetic Scheme
Based on the origin (Genesis) of rocks
Igneous Rock
Freezing (solidification) of molten
What are Sedimentary Rocks?
They are rocks formed by the cementation of grains. Precipitation of minerals from a water solution.
What are metamorphic rocks
Rocks that form when pre existing rocks change character due to a change in temperature and/or pressure conditions
Does the rock cycle have a begining?
No
Does the rock cycle have an end?
No
What does it mean when an igneous environment is considered extrusive?
Cools at or near the surface
What does it mean when an igneous environment is intrusive?
Cools at depth
What is magma?
Underground melt
What is Lava?
Melt on the surface
What happens with extrusive igneous rock
Cools quick at surface
What happens with INTRUSIVE igneous rock?
Cool slowly underground
List some sources of heat
-Radiation from the sun
-Radioactive decay (Mostly crustal)
-50% of heat is leftover from Earth’s formation
-Planetesimal accretion
-Gravitational Compression
-Iron differentiation, Moon formation,
-Meteorite bombardment
Mantle is solid because of extremely ____ ____ in Earth’s interior
High pressure
Why is the pressure in Earths interior so high? (Mantle is solid because of this)
Atoms are prevented from breaking free
3 ways to melt rock
-Decompression melting of rock (decrease pressure)
-Heat transfer melting (increase temperature of the rock)
-Flux melting (add volatiles)
Crystalline Classification: Fast cooling
Means small gran size (extrusive)
Crystalline Classification: Slow cooling
Large grain size (intrusive)
Melt chemistry varies due to
-Initial source rock composition
-Assimilation
-Magma mixing
-Partial melting
What does partial melting result in
Partial melting yields a silica rich magma
Removing a partial melt from its source creates what?
Felsic magma and mafic residue
What is Fractional crystallization
Sequential crystal formation and settling
What is the movement of melt
Speed of magma flow governed by viscosity
What does Low viscosity mean
Magma flows easier
What does high viscosity mean
Magma does not flow as easy
Viscosity depends on what?
-Silica content
-Temperature
-Volatile content
Low Si means
Low viscocisity
High Si means
High viscosity
Depth
Deeper is hotter and shallow is cooler
Shape
Spherical bodies cool slowly
Groundwater
Circulating water removes heat
Pyroclastic flow
Ash and debris avalanche
Dike
Cuts across pre existing layers
Sill
Injected parallel to the rock layers
Plutons
Blob shaped intrusions
Batholith
Group of plutons
Aphanitic means
fine grained
Phaneritic means
Coarse grained
Pyroclastic
Rock fragments from violent eruptions
Volcaniclastic rock
comprised of volcanic fragments
Sediments
Loose fragments of rocks or minerals, shells and shell fragments, or mineral crystals
Clasts
Individual grains within sedimentary debris
Weathering
Physical (mechanical) and chemical breakdown of rock at earth’s surface
Regolith
Layer of debris resulting from weathering
Joints
Natural cracks
Exfoiliation
Occurs in exposed plutons
Frost wedging
Water expands 9% when frozen. BIG PRESSURE
Root wedging
Roots intrude fractures and pry rock apart as plant grows
Oxidation
Reactions during which an element loses electrons usually occurring when elements combine with oxygen (rusting)
Hydrolysis
Water chemically reacts with minerals to form other minerals that incorporate water
Dissolution
When soluble materials dissolve in water
Clastic sedimentary rocks
Cemented mineral grains/rock fragments
Lithification
Transforms loose sediment into a rock by either compaction or cementation
Angularity
Degree of an edge
Sorting
Uniformity of grain size
Fast flow
Large clast size
Sedimentary maturity
Mature sediments are well sorted and well rounded
Diatoms
Single celled algae with cell wall made of silica
