GEOL 102 Terms

The Scientific Method

(1) Observation (2) Question (3) Research (4) Hypothesis (5) Tests (6) Results

composition

Materials
continents, oceanic crust, mantle, outer core(liquid), inner core(solid)

Rheology

Behavior
lithosphere(crust & upper mantle, rigid, brittle) asthenosphere(mantle, ductile)

impact craters

created by celestial bodies such as asteroids or meteors slamming into the Earth's crust and leaving a big hole in the ground

Location of volcanoes related to plate boundaries.

Volcanoes form at mid ocean ridges, and on the continental side of subduction zones
Volcanoes appear at MORs because as the oceanic plates split apart, new lava must replace the rock being subducted at the other ends of the plates.
Volcanoes appear on the

spreading/divergent/MOR

A place in the Earth's crust where the crust is splitting apart
Typically seen at mid ocean ridges (MORs)

convergent/subduction/continental collision

A place where two plates are colliding
When an oceanic plate collides with a continental plate the oceanic plate subducts because it is denser.
This creates a subduction zone
When two continental plates converge they slam into each other to create massive

transform

a place where two plates move parallel to the surface and eachother

continental margins: active vs. passive.

Active margin- the place of a subduction zone of a continental and oceanic plate
Passive margin- the continental shelf dips below sea level for some time before reaching an oceanic plate.

Continental drift

the idea that continents have moved and are still moving slowly across the earth's surface

glacial striations

glacier scratches in sediment
leaves evidence

fossils

fossil occurrences proved land animals existed in both paleozoic and mesozoic eras

seafloor magnetic anomalies

Around mid-ocean ridges
Magnetic Stripes that are symmetric above MOR
Strength of earths real dipole field and at a given place
Occurs where basalt has normal polarity
Basalt adds to force to get stronger magnetic signal

seafloor spreading

Divergence at MOR
The MOR pushes rock away at a slow rate to push continents farther away from each other.
The rocks near the continents are old subduct
The rock near the MOR is new and young

Driving forces: ridge push

Ridge push- As the crust around the MOR rises due to mantle upwelling and the extra crust surrounding MOR, the combined forces try to push the plates down and apart.

Driving forces: slab pull

Slab pull- as a part of the oceanic crusts subducts into the mantle, the subducting crust pulls the surrounding crust down in a chain reaction that goes across the entire plate until it reaches the MOR on the other side.
This is more powerful than ridge p

Driving forces: convection

Convection- currents in the mantle that cause continental and oceanic plates to collide. Convection is the underlying force that creates subduction zones and MORs

Definition of a mineral

Solids
Naturally occurring
Inorganic
Crystalline structure
Specific chemical make-up

Atomic structure of elements

All atoms consist of a protons, neutrons, and electrons
The protons and neutrons are in the nucleus and contain most of the atom's mass while electrons orbit the atom in energy shells
Protons are positively charged
Neutrons carry no charge
Electrons are n

ionic bonding

Ionic bonds are created when an atom gives up electrons to another atom
This creates a positively charged cation and a negatively charged anion
Ex: Table salt, (NaCl)
Are relatively weak and can typically be broken if the compound is placed in a solvent s

covalent bonding

Covalent bonds are created when two or more atoms share electrons
The atoms do not create ions nor are they charged
The sharing of electrons is typically much stronger than ionic bonds
Ex: Sugar (C2H12O6)

metallic bonding

Metallic bonds
Metals share electrons freely and electrons can pass from one atom to the next without creating any charges
Electrons can be freely passed from one metal to another
Ex, an electric current running through a nickel and copper wire
Metals are

Silica tetrahedra (charge)

A silica tetrahedral has a charge of -4

independent silicates

Independent silicates are ultramafic

single chain silicates

Single and double chain silicates are mafic

double chain silicates

Single and double chain silicates are mafic

sheet silicates

Sheet and framework silicates are felsic

framework silicates

Sheet and framework silicates are felsic

Polymorphs

minerals with the same chemicals but different structure

phase diagrams and relationship to density

shows change in chemical make-up of minerals at different temperatures and pressure

Location of key minerals in the Earth (olivine, quartz, feldspar)

Feldspar&Quartz found in continental crust Olivine found anywhere deep in the mantle(ultramafic)

Mantle minerals (olivine, spinel, modified spinel, perovskite, postperovskite)

Olivine-Upper mantle
Modified Spinel-Upper mantle
Spinel-Upper mantle
Perovskite-Lower mantle
Postperovskite-Lower mantle

Rocks Definition

a coherent, naturally occurring solid, consisting of an aggregate of minerals or a mass of glass

igneous

created from liquid rock

sedimentary

formed by deposits building up in layers
Clastic- minerals deposits build up over time in layers
Chemical- substances come out of solution and are deposited on the crust
Biochemical- life forms take minerals and create shells or create shelters in the for

metamorphic

Created by sedimentary and igneous rocks changing in a combination of heat and pressure.

The rock cycle

igneous rocks can only be formed by liquid rock
Sedimentary rocks are formed through the weathering and erosion of Igneous, Metamorphic and Sedimentary rocks
Metamorphic rocks are formed when Igneous, Sedimentary, and Metamorphic rocks are put under heat

Melting: thermal

heat transfer?

Melting: decompression

occurs where hot mantle rock rises to shallower depths

Melting: wet

Water pockets get sucked under land, crates addition of heat melting. Occurs in subduction zones.

Bowen's reaction series, its relationship to crystallization/melting temperatures of differentsilicate minerals

The sequence of mineral-producing reactions that take place in a cooling, initially mafic, magma.

Magma differentiation processes (fractional crystallization

cooling magma crystalizes mafic components
mafic minerals get left behind while felsic materials stay in magma

Magma differentiation processes assimilation,

incorporation of country rock into magma
makes magma more felsic

Magma differentiation processes partial melting

increases temperature so only part of the rock melts
melt is more felsic than original rock

Magma migration

fracture the crust/country rock
melt
magma rises because it is less dense. moves through fractures and causes some melting.

Intrusive vs. extrusive textures

EXTRUSIVE: aphanitic,porphyritic, pahoehoe, aa, bombs, vesicles, pumice, ash
INTRUSIVE: coarse, plutonic, porphyritic

Intrusive rocks (granite, gabbro, peridotite)

Felsic----Mafic----Umafic
Granite--Gabbro---Peridotite

Igneous texture

fine grained = extrusive/volcanic, cant see individual crystals cools quickly
coarse grained = intrusive/plutonic,porphyritic, can see crystals cools slowly and at depths

pluton

cooled magma chamber

batholith

a chain of plutons

dike

a vertical planer magma body

sill

a horizontal planer magma body

vein

are monominerolic (containing only one mineral)
Created by hydrothermal fluids

Extrusive rock type variation with composition (rhyolite, andesite, basalt)

Felsic-----Int-----Mafic
Rhyolite-Andesite--Basalt

porphyritic

contains both large and small crystals

pahoehoe

ropey, is relatively hot at eruption

aa

chunky/sharp, is relatively cool at eruption

vesicles

formed when gas escapes cooling lava, often contains trapped gasses

pumice

lava that has many vesicles, often floats in water

aphanitic

no crystals are formed, glassy in appearance

bombs

the volcanic formation from a fountain eruption

ashfall tuff

ash columns?

tuff

pyroclastic igneous rock composed of ash, fragmented lava and pumice

welded tuff

tuff formed by the welding together of hot volcanic glass shards at the base of pyroclastic flows

ignimbrites

pumice-dominated pyroclastic flow deposits with subordinate ash
well-compacted, often partially welded, layers that in some cases resemble lava flows

lahar

massive mudslide

Controlling factors of volcanic eruptive power: silica content, gas content

Silica content affects the viscosity of the magma
The higher the silica content, the more viscous the magma
Gas content affects how violent the eruption will be
Higher gas content creates more violent eruptions

shield

mafic
Shield volcanoes are broad, low-profile features

cinder

Cinder cones
-fountain eruptions
-relatively small
-1 eruption
-cinder sand
-near larger volcanoes

stratovolcano

Their lower slopes are gentle, but they rise steeply
form at convergent plate margins, where one plate descends beneath an adjacent plate at the site of a subduction zone.

ash flow

Ash flow Volcanoes
-"big beasts"
-super volcanoes
-pressure gets so hot that it explodes and it collapses on itself
-creates a caldera
-lots of volume
-felsic magma
-viscosity important

fissure eruptions

fissure eruptions are generated at several contemporaneous sites along a linear fracture

Hazards pyroclastic flow

-really dangerous, horrible, hot gas, moving faster than anything else
-extremely strong blasts

Hazards lahars

-when snow melts and mixes with ash and creates mud flows
-mudslides

Hazards ash

-have warning systems
-USGS

Volcanoes and climate

-ash can cool down the earth when ash covers sun

Why study geology?

major pattern is plate tectonics and to discover what rocks are made up of

How do we study geology?

Observations,

calderas

formed when a volcano becomes dormant and erodes. The volcano eventually collapses into its massive lava chamber and a caldera is formed.

salt domes

created when salt veins reach the Earth's surface and rain dissolves and washes the minerals away leaving a crater in the ground.

Location of earthquakes related to plate boundaries.

Earthquakes occur along plate boundaries and are caused by movement in the crust
This movement can be a subduction, a "push" on a continental collision boundary, a spreading at an MOR boundary, or two plates moving rapidly past each other in a transform b

atomic number

Atomic number is determined by the number of protons an atom has in its nucleus

atomic mass

Atomic mass is determined by the number of protons and neutrons located in the nucleus Atoms with the same number of protons but differing numbers of neutrons are called isotopes

formation of ions

There are two types of ions called cations and anions and are formed when an element gains or loses electrons
Cations are positively charged ions
Were created when an element lost its outer electron shell to be reduced to a full electron shell at a lower

continental crust

felsic
Density=2.7
42km thick

oceanic crust

mafic
density=3.0
8kn thick

mantle

ultramafic
density=3.3

Mafic

igneous rocks or magmas that are rich in iron and magnesium but relatively poor in silica

Felsic

igneous rocks that are rich in elements forming feldspar and quartz

Ultramafic

igneous rocks or magmas that are rich in iron and magnesium but poor in silica