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felsic - phaneritic
granite
felsic - aphanitic
rhyolite
intermediate - phaneritic
diorite
intermediate - aphanitic
andesite
mafic - phaneritic
gabbro
mafic - aphanitic
basalt
ultramafic - phaneritic
peridotite
equigranular
texture in igneous rocks where the crystals are of similar size
porphyritic
texture in igneous rocks characterized by large crystals embedded in a finer-grained matrix
felsic
igneous rocks that are rich in silica and light-colored minerals
intermediate
igneous rocks that have a composition between felsic and mafic, containing a mix of light and dark minerals
mafic
igneous rocks that are rich in magnesium and iron, typically darker in color
Where do we find felsic rocks?
continental hot spots, associated with volcanic activity, particularly in areas of subduction and continental rifting
Where do we find mafic rocks?
oceanic crust, commonly found in mid-ocean ridges and volcanic islands, ocean hot spots
Where do we find intermediate rocks?
subduction zones, volcanic arcs, and continental margins
Phenocrysts
form in the magma and are brought up in the magma
Xenocrysts/xenoliths
didn’t form in the magma, brought along by the magma
bedrock
rock that is attached to Earth’s crustand is the solid foundation beneath soil and loose material
outcrop
exposure of bedrock at the surface
weathering
the process of breaking down rocks and minerals through physical, chemical, or biological means
erosion
the process by which rocks and soil are worn away and transported by natural forces such as water, wind, or ice
What are sedimentary rocks formed from?
the accumulation and compaction of mineral and organic particles over time or salts that have dried out of a solution
deposition
the process by which sediments, soil, and rocks are added to a landform or land mass, often through water, wind, or ice
lithification
the process of turning sediments into solid rock through compaction and cementation.
What are the steps in producing a sedimentary rock?
weathering, erosion, transportation geomorphological processes, deposition, compaction and lithification
strata/beds
layers of sedimentary rock
clastic
sedimentary rocks formed from fragments of pre-existing rocks
biochemical, organic
sedimentary rocks formed from the remains of living organisms or biological processes.
chemical
sedimentary rocks composed of ions that have precipitated out of solution
conglomerate
a coarse-grained sedimentary rock composed of rounded fragments within a matrix of finer grained material
breccia
a sedimentary rock made up of sharp-angled fragments of minerals or rocks that are cemented together by a fine-grained matrix
epicenter
a location on the Earth’s surface directly above the focus
Fault surface (plane)
the fracture surface between one block and another along which movement occurs.
Focus
‘origin’ of the earthquake
Seismic waves
waves of energy that travel like shock waves from the focus to the surrounding area
P-wave
primary, compression wave
S-wave
secondary, shear wave
Types of Faults
strike-slip, normal, thrust, and reverse
Main shock
biggest earthquake in the cluster
Foreshock
occurs before the main shock
Aftershock
occur after the main shock
What is the scale we use to measure earthquakes?
Moment magnitude scale (Mw)
Quantitative
property of something that is a measurement
Qualitative
property of something that is descriptive. A subjective measure
Causes of earthquakes: natural events
creation of a new fault, movement along an old fault, movement of magma below the surface or a volcanic explosion, huge landslide
Causes of earthquakes: anthropogenic
underground nuclear explosive tests, fracking, wastewater injection
Elastic Rebound Theory
Energy is stored in the form of elastically deformed rock. When strain exceeds rock strength, the rock fractures and energy is released
Body waves
P and S-waves, travel through the Earth’s interior
Surface waves
love and rayleigh waves, travel along the surface of the lithosphere
Layers of the Earth
Crust, Upper Mantle, Aesthenosphere, Lower Mantle, Outer Core, Inner Core
Love Wave
cause horizontal shifting at the surface of the Earth
Rayleigh wave
rotating waves along surfaces, create vertical displacement (movement), like ripples on water
Divergent Boundaries
Shallow earthquakes within ocean basins, foci are located:
• Along mid-ocean ridges
• Along transform faults
Transform-Fault Boundaries
Strike-slip fault mechanism due to shearing forces from tectonic plate movement, Can produce large, destructive earthquakes
Convergent Boundaries
Largest earthquakes occur at subduction zones called megathrust earthquakes
Earthquakes cause damage in what ways?
Faulting and shaking – primary hazards, Landslides, Liquefaction, Tsunamis, Fires
Ordovician Period
505 to 440 Ma. First vertebrates, fish appear, Evidence of glaciation, sea level lower, Mass extinction at the end
Silurian Period
440 to 410 Ma. Age of corals and reefs. • Sharks, toothed fish • First primitive land plants and insects
Devonian Period
410 to 360 Ma - ‘Potash’ evaporite sedimentary deposits, deposited in shallow saline seas. • Land plants (e.g., trees) and insects thrive • Evidence of glaciation • Mass extinction at end. Pangaea supercontinent begins to form
Carboniferous Period
360 to 286 Ma First reptiles. • Huge swamps and the first global coal forming period. • Coal forming in area that would become Estevan, SK • Appalachian Mountains beginning to form.
Permian Period
286 to 245 Ma • Formation of Pangaea – a super continent. • Glaciation in the Southern Hemisphere - Extinction! 300 mile crater found in Antarctica (2006) • Volcanic activity in Siberia, dust >CO2 in atmosphere, warming. • End of the Paleozoic
Triassic Period
245 to 208 Ma • Pangea starts to breakup. Mid-Atlantic ridge forms, • Deserts. Warm climate. • First small dinosaurs & first primitive mammals
Jurassic Period
208 to 146 Ma • Dinosaurs rule! Large & diverse dinosaurs and marine vertebrates. • First birds. Eosinopteryx in Chinese forests 150 Ma
Cretaceous Period
146 to 65 Ma • Global climate MUCH warmer • First flowering plants • Tyrannosaurus rex dominates the plains.
Tertiary Period
65 to 2.6 Ma • Giant beavers (60-100 kg), giant bears, mastodons, giant sloths • Last wooly mammoths
Quaternary period
2.6 Ma to the present • First hominids • 20 Ma human-like primates • Homo 2.4 Ma, Homo erectus 1.6 Ma - Ice Age (again), at least 4 major glacial and interglacial periods (ice retreat of continental glaciers)
Holocene Epoch
the current geological epoch, beginning around 11,700 years ago and continuing to the present day. It's also known as the "Age of Man" because of the significant impact humans have had on the planet during this time
Magma
originates deep within the Earth’s lithosphere / upper mantle due to the melting of rock and associated minerals
Lava
the name given to molten rock when it reaches the Earth’s surface from volcanic activity
extrusive
Igneous rocks that reach the Earth’s surface cool, solidify, and crystallize relatively quickly. aphanitic texture
How do metamorphic rocks form?
Transformation of pre-existing rock due to: high temperature, high pressure, and (sometimes) chemically active hot fluids.
At what temperature and depth does a rock start to metamorphose?
around 250°C, typically at depths > 8 km
Foliation
planar or wavy structure that results from the flattened growth of minerals in a metamorphic rock
Foliation develops through:
rotation of minerals, change in mineral shape, and recrystallization
Non-foliated rocks occur when:
the pressure is low or equal from all directions (contact metamorphism), or the composition of the rock does not include platy minerals such as mica
Contact metamorphism
hot magma chambers ‘bake’ the relatively cooler ‘host rock’ (country rock) where they come in contact
Seafloor metamorphism
Only takes place in the ocean, Common around mid ocean ridges, mafic rocks, greenschist
Regional metamorphism
associated with mountain building and plate tectonics occurs over a large area
Burial metamorphism
temperature increases with depth and the geothermal gradient • No directed pressure acting on the rocks, just weight of overlying rocks
Shock Metamorphism
Results from meteorite impacts, Leaves evidence in the mineral grains, e.g., planar fractures in quartz grains
Hot spots
Mantle plume: upwelling of hot rocks in convectional cells in the mantle to the base of the lithosphere. Heat from the plume melts overlying rocks and magma seeps up to surface creating a volcano.
pyroclastic material
solid rock fragments ejected during an eruption
Tephra
Air-borne pyroclastic material
Pahoehoe
basaltic flow of lower viscosity (more fluid), ropy structure
Aa lava
sharp, spiny, surface, basaltic deposit of higher viscosity (less fluid)
Shield volcano
The largest conical volcanoes. Formed from basalt. Gentle slopes (5o - 12o). Eruptions via fissures and vents, often form lava lakes in a large vent. Lava flows quickly and over great distances. Lava rivers and lava tubes common
Cinder cones
A small volcano cone (a few 100 m in diameter) • The slope angle is approximately 24-32o on average from the horizontal (angle of repose). Smaller in size and shorter life span • Often form on the sides of shield volcanoes
Composite cones (stratovolcanoes)
Intermediate in size and average composition •Variable slope angles but often have a distinctive conical shape •Located along subduction zones, Can be inactive for long periods of time before eruptions
Flood basalt
• Basaltic lava flow, very fluid, ejected from a fissure (crack) and flooding a large area • Fed from mantle plumes
Caldera volcano
A volcanic crater that develops from the explosion and collapse of a composite volcano. • some of the largest features (20 to 40 kms wide) and form from violent, often infrequent eruptions (10,000 yr frequency).
Mid ocean ridges
Have earthquakes, hot water emissions • Basaltic magma
Lava Domes
lava too viscous to flow and piles up at vent. Cools quickly generating glassy high silica obsidians
Spatter cones
very small basaltic cones, build up around vents where magma is splattered by bubbles of gasses
Fumarole
vents that emit hot gases, can be 1000ºC.
Gases
CO2 and H2 S are invisible, but can asphyxiate or poison people. can also dissolve in water droplets in the air and lead to acid rain
Pyroclastic flow
Avalanche of hot gas and pyroclastic material. • E.g., Mt Vesuvius, Italy (79 AD)
Lahar
volcanic debris flow (hot mud flow)
Phreatic explosions
Occur when magma comes in contact with water or ice • Occurs in subterranean volcanoes or island arc volcanoes